7.C: Lab Safety - Industrial Safety and Manufacturing
Hazards, Hazard Recognition, Hazard Categories
Machine operations expose workers to both physical hazards and physiological (ergonomic hazards). Using the Safety Precautions for Milling Machines and after viewing the video below on ergonomic safety, identify precautions that may reduce risk for ergonomic injury. Are the precautions identified sufficient? Can you provide additional precautions?
Video: Ergonomic Awareness-Dr. Ergo
Performance Standards and Design Standards
Some safety standards are performance driven in nature, meaning an action or activity is performed to achieve the safety objective or required protection. Other standards are design standards, meaning the safety function or requirement is assured by some design specification or feature in a system or equipment.
Referencing the Safety Precautions for Milling Machines , distinguish 'performance' precautions and 'design' precautions.
Standard Mapping
Map the ten referenced standards for machine presses to a physical hazard and then categorize as either design or performance.
Mechanical power press guarding and construction, general -
Hazards to personnel associated with broken or falling machine components . Machine components shall be designed, secured, or covered to minimize hazards caused by breakage, or loosening and falling or release of mechanical energy (i.e. broken springs).
1910.217(b)(4)(i)
The pedal mechanism shall be protected to prevent unintended operation from falling or moving objects or by accidental stepping onto the pedal.
1910.217(b)(7)(v)(a)
Each hand control shall be protected against unintended operation and arranged by design, construction, and/or separation so that the concurrent use of both hands is required to trip the press.
1910.217(b)(8)(i)
A main power disconnect switch capable of being locked only in the Off position shall be provided with every power press control system.
1910.217(b)(11)
Hydraulic equipment . The maximum anticipated working pressures in any hydraulic system on a mechanical power press shall not exceed the safe working pressure rating of any component used in that system.
1910.217(c)(3)(iv)(b)
Attachments shall be adjusted to prevent the operator from reaching into the point of operation or to withdraw the operator's hands from the point of operation before the dies close.
1910.217(c)(4)
Hand feeding tools . Hand feeding tools are intended for placing and removing materials in and from the press. Hand feeding tools are not a point of operation guard or protection device and shall not be used in lieu of the "guards" or devices required in this section.
1910.217(d)(1)(i)
Use dies and operating methods designed to control or eliminate hazards to operating personnel, and
1910.217(d)(1)(ii)
furnish and enforce the use of hand tools for freeing and removing stuck work or scrap pieces from the die, so that no employee need reach into the point of operation for such purposes.
1910.217(e)(1)(i)(A)
Conduct periodic and regular inspections of each power press to ensure that all of its parts, auxiliary equipment, and safeguards, including the clutch/brake mechanism, anti-repeat feature, and single-stroke mechanism, are in a safe operating condition and adjustment;
1910.217(e)(1)(ii)(A)
Inspect and test each press on a regular basis at least once a week to determine the condition of the clutch/brake mechanism, anti-repeat feature, and single-stroke mechanism
Automation and Robotics Lab Safety
Images
Standard Mapping - Robotics Lab Safety
There is no subpart in the OSHA safety standards that specifically calls out robotics or automation safety. However OSHA does provide guidance on Robotics Safety . Robots are machines that handle materials and manufacture parts and materials. Sections 2.1.1-2.1.5 of the FANUC Handling Tool Operations Manual are repeated below. Map each safety warning, procedure, or protocol to the standard most likely the bases for the direction. Keep in mind that OSHA's incorporation by reference of design standards and general duty clause taken together require employers to follow safety guidelines and protocols offered by the design standards and the manufacturer. For any general duty rule also add why you believe the precaution falls under general duty.
A safe workcell is essential to protect people and equipment. Observe the following guidelines to ensure that the workcell is set up safely. These suggestions are intended to supplement and not replace existing federal, state, and local laws, regulations, and guidelines that pertain to safety.
- Sponsor your personnel for training in approved FANUC Robotics training course(s) related to your application. Never permit untrained personnel to operate the robots.
- Install a lockout device that uses an access code to prevent unauthorized persons from operating the robot.
- Arrange the workcell so the operator faces the workcell and can see what is going on inside the cell. Clearly identify the work envelope of each robot in the system with floor markings, signs, and special barriers. The work envelope is the area defined by the maximum motion range of the robot, including any tooling attached to the wrist flange that extend this range
- Position all controllers outside the robot work envelope.
- Mount an adequate number of EMERGENCY STOP buttons or switches within easy reach of the operator and at critical points inside and around the outside of the workcell. flashing lights and/or audible warning devices that activate whenever the robot is operating, that is, whenever power is applied to the servo drive system. Audible warning devices shall exceed the ambient noise level at the end-use application
- Wherever possible, install safety fences to protect against unauthorized entry by personnel into the work envelope
- Install special guarding that prevents the operator from reaching into restricted areas of the work envelope
- Use presence or proximity sensing devices such as light curtains, mats, and capacitance and vision systems to enhance safety
- Periodically check the safety joints or safety clutches that can be optionally installed between the robot wrist flange and tooling. If the tooling strikes an object, these devices dislodge, remove power from the system, and help to minimize damage to the tooling and robot
- Make sure all external devices are properly filtered, grounded, shielded, and suppressed to prevent hazardous motion due to the effects of electro-magnetic interference (EMI), radio frequency interference (RFI), and electro-static discharge (ESD)
- Make provisions for power lockout/tagout at the controller
- Eliminate pinch points. Pinch points are areas where personnel could get trapped between a moving robot and other equipment
- Provide enough room inside the workcell to permit personnel to teach the robot and perform maintenance safely
- Know the path that can be used to escape from a moving robot; make sure the escape path is never blocked
Standard Mapping Table
| OSHA SUBPART | FANUC SAFETY PROTOCOL |
|---|---|
| 1910 SUBPART D | |
| 1910 SUBPART E | |
| 1910 SUBPART J | |
| 1910 SUBPART O | |
| 1910 SUBPART S | |
| GENERAL DUTY CLAUSE |


9.9: Interpersonal Communication References
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Augsburger, David W. Conflict Mediation across Cultures: Pathways and Patterns . Louisville, KY:Westminster/John Knox, 1992. Print.
Baxter, L.A. “Dialectical Contradictions in Relational Development.” Journal of Social and Personal Relationships 7 (1990): 69-88. Web.
Bell, Sandra, and Simon Coleman. “The Anthropology of Friendship: Enduring Themes and Future Possibilities.” The Anthropology of Friendship . Oxford, UK: Berg, 1999. 1-20. Print.
Booth, Melanie. “Boundaries And Student Self-Disclosure In Authentic, Integrated Learning Activities And Assignments.” New Directions For Teaching & Learning 2012.131 (2012): 5-14. Academic Search Premier. Web. 8 Oct. 2014.
Burleson , Brant R., Amanda J. Holmstrom, and Susanne M. Jones. “Some Consequences for Helpers Who Deliver “Cold Comfort”: Why It’s Worse for Women than Men to Be Inept When Providing Emotional Support.” Sex Roles 53.3-4 (2005): 153-72. Web.
Carrier, J. G. “People Who Can Be Friends: Selves and Social Relationships.” The Anthropology of Friendship . Ed. Sandra Bell and Simon Coleman. Oxford, UK: Berg, 1999. 21-28. Print.
Coates, Jennifer. Women, Men, and Language: A Sociolinguistic Account of Sex Differences in Language . London: Longman, 1986. Print.
Cole, Mark. I nterpersonal Conflict Communication in Japanese Cultural Contexts . N.p.: n.p., 1996. Print.
Echols, Leslie, and Sandra Graham. “Birds of a Different Feather: How Do Cross-Ethnic Friends Flock Together?.” Merrill-Palmer Quarterly , 59.4 (2013): 461-488.
Harriman, Ann. Women/men/management . New York: Praeger, 1985. Print.
Kim, Kyungil, and Arthur Markman. “Individual Differences, Cultural Differences, and Dialectic Conflict Description and Resolution.” International Journal of Psychology , 48.5 (2013): 797-808.
Luft, Joseph. Of Human Interaction . Palo Alto, CA: National, 1969. Print.
Mathews, Alicia, Valerian J. Derlega, and Jennifer Morrow. “What Is Highly Personal Information and How Is It Related to Self-Disclosure Decision-Making? The Perspective of College Students.” Communication Research Reports 23.2 (2006): 85-92. Web.
Monsour, Mike, and William K. Rawlins. “Transitional Identities And Postmodern Cross-Gender Friendships: An Exploratory Investigation.” Women & Language 37.1 (2014): 11-39. Communication & Mass Media Complete. Web. 19 Nov. 2014.
Nishina, Adrienne, Jaana Juvonen, and Melissa R. Witkow. “Sticks and stones may break my bones, but names will make me feel sick: The psychosocial, somatic, and scholastic consequences of peer harassment.” Journal of Clinical Child and Adolescent Psychology 34.1 (2005): 37-48.
Olson, David, and H. McCubbin. Families: What Makes Them Work . Thousand Oaks, CA: Sage Publications, 1983. Print.
Özad, Bahire Efe, and Gülen Uygarer. “Attachment Needs and Social Networking Sites.” Social Behavior and Personality: An International Journal 42.1 (2014): 43-52. Web.
Pearson, Judy C. Communication in the Family: Seeking Satisfaction in Changing times . Vol. 2. New York: Harper & Row, 1992. Print.
Rahim, M. Afzalur. Managing conflict in organizations . Transaction Publishers, 2015.
Rahim, M. Afzalur, and Nace R. Magner. “Confirmatory factor analysis of the styles of handling interpersonal conflict: first-order factor model and its invariance across groups.” Journal of applied psychology 80.1 (1995): 122.
Rawlins, W. K. (1981). Friendship as a communicative achievement . Temple University.
Thomas, Kenneth Wayne, and Ralph H. Kilmann. Thomas-Kilmann Conflict Mode Instrument . Tuxedo, NY: XICOM, 1974. Print.
Wood, Julia T. Interpersonal Communication in Everyday Encounters . 2nd ed. Belmont, CA: Wadsworth, 1999. Print.
Contributions and Affiliations
- Survey of Communication Study. Authored by : Scott T Paynton and Linda K Hahn. Provided by : Humboldt State University. Located at : en.wikibooks.org/wiki/Survey_of_Communication_Study. License : CC BY-SA: Attribution-ShareAlike


15.3: Burnside's Lemma
Burnside's lemma relates the number of equivalence classes of the action of a group on a finite set to the number of elements of the set fixed by the elements of the group. Before stating and proving it, we need some notation and a proposition. If a group \(G\) acts on a finite set \(\mathcal{C}\), let ~ be the equivalence relation induced by this action. (As before, the action of \(\pi∈G\) on \(\mathcal{C}\) will be denoted \(\pi^∗\).) Denote the equivalence class containing \(C∈\mathcal{C}\) by ⟨\(C\)⟩. For \(\pi∈G\), let \(fix_C(\pi)=\{C∈ \mathcal{C}:\pi^∗(C)=C\}\), the set of colorings fixed by \(\pi\). For \(C∈ \mathcal{C}\), let \(stab_G(C)=\{\pi∈G: \pi (C)=C\}\) be the stabilizer of \(C\) in \(G\), the permutations in \(G\) that fix \(C\).
To illustrate these concepts before applying them, refer back to Figure 15.2 . Using that information, we can determine that \(fix_C(r_2)=\{C_1,C_{10},C_{11},C_{16}\}\). Determining the stabilizer of a coloring requires finding the rows of the table in which it appears. Thus, \(stab_{D8}(C_7)=\{ι,h\}\) and \(stab_{D8}(C_{11})=\{ι,r_2,p,n\}\).
Let a group \(G\) act on a finite set \(\mathcal{C}\) . Then for all \(C \in \mathcal{C}\) ,
\(\displaystyle \sum_{C' \in ⟨C⟩} |stab_G(C')| = |G|\).
- Proof
-
Let \(stab_G(C)=\{\pi_1,…,\pi_k\}\) and \(T(C,C′)=\{\pi∈G:\pi^∗(C)=C′\}\). (Note that \(T(C,C)=stab_G(C)\).) Take \(\pi∈T(C,C′)\). Then \(\pi \circ \pi_1 ∈T(C,C′)\) for \(1≤i≤k\). Furthermore, if \(\pi \circ \pi_i = \pi \circ \pi_j\), then \(\pi^{-1} \circ \pi \circ \pi_i = \pi^{-1} \circ \pi \circ \pi_j\). Thus \(\pi_i = \pi_j\) and \(i=j\). If \(\pi'∈T(C,C′)\), then \(\pi^{−1} \circ \pi′∈T(C,C)\). Thus, \(\pi−1 \circ \pi′=\pi_i\) for some \(i\), and hence \(\pi′= \pi \circ \pi_i\). Therefore \(T(C,C′)=\{\pi \circ \pi_1,…,\pi \circ \pi_k\}\). Additionally, we observe that \(T(C′,C)=\{\pi^{-1}:\pi∈T(C,C′)\}\). Now for all \(C′∈⟨C⟩\),
\(|stab_G(C′)|=|T(C′,C′)|=|T(C′,C)|=|T(C,C′)|=|T(C,C)|=|stab_G(C)|\).
Therefore,
\(\displaystyle \sum_{C' \in ⟨C⟩} |stab_G(C')| = \sum_{C' \in ⟨C⟩} |T(C,C')|\).
Now notice that each element of \(G\) appears in \(T(C,C′)\) for precisely one \(C′∈⟨C⟩\), and the proposition follows.
With Proposition 15.8 established, we are now prepared for Burnside's lemma.
Let a group \(G\) act on a finite set \(\mathcal{C}\) . If \(N\) is the number of equivalence classes of \(\mathcal{C}\) induced by this action, then
\(N = \dfrac{1}{|G|} \displaystyle \sum_{\pi \in G} |fix_{\mathcal{C}}(\pi)|\).
Before we proceed to the proof, note that the calculation in Burnside's lemma for the example of 2-coloring the vertices of a square is exactly the calculation we performed at the end of Section 15.1.
- Proof
-
Let \(X=\{(\pi,C) \in G \times \mathcal{C}: \pi (C)=C\}\). Notice that \(\sum_{\pi \in G} |fix_C(\pi )|=|X|\), since each term in the sum counts how many ordered pairs of \(X\) have \(\pi\) in their first coordinate. Similarly, \(\sum_{C \in \mathcal{C}}|stab_G(C)|=|X|\), with each term of this sum counting how many ordered pairs of \(X\) have \(C\) as their second coordinate. Thus, \(\sum_{C \in \mathcal{C}} |fix_C(\pi)|=\sum_{C \in \mathcal{C}} |stab_G(C)|\). Now note that the latter sum may be rewritten as
\(\displaystyle \sum_{equivalence \\ classes ⟨C⟩} (\sum_{C' \in ⟨C⟩} |stab_G(C')|)\).
By Proposition 15.8 , the inner sum is \(|G|\). Therefore, the total sum is \(N \cdot |G|\), so solving for \(N\) gives the desired equation.
Burnside's lemma helpfully validates the computations we did in the previous section. However, what if instead of a square we were working with a hexagon and instead of two colors we allowed four? Then there would be \(4^6=4096\) different colorings and the dihedral group of the hexagon has 12 elements. Assembling the analogue of Figure 15.2 in this situation would be a nightmare! This is where the genius of Pólya's approach comes into play, as we see in the next section.


9.6: Summary
9.1 Assessing Functional Ability
Assessing a patient’s functional status is important in planning care. There are many validated and standardized tools to assess the patient’s baseline status. These tools are to be used not only by the nurse but also with input and discussion among the interprofessional team members, such as physical therapy, occupational therapy, physicians, other nurses, and patient care technicians. Nurses and their colleagues should always have a plan of care based on their assessment and data from the tool. This allows for a personalized plan with interventions to promote patients’ functional abilities and improve ADLs. There are many simple exercises patients can perform to improve their ADL functionality. Some exercises only require body weight such as isotonic and isometric exercises, and others may require minimal equipment, such as a resistance band, for isokinetic exercises.
9.2 Assessing Mobility
This section identified key factors that affect mobility. Internal factors such as changes due to aging and medical conditions should be combined with external factors such as climate and housing structure. A comprehensive mobility assessment includes ROM, posture, gait, balance, and strength measurements to gather data about a patient’s mobility status. Limitations in mobility can affect multiple body systems, so improving mobility and educating patients on the importance of mobility is essential for healthy living.
9.3 Transferring Patients
Safe patient handling includes techniques in transferring, lifting, and ambulating patients using assistance from nurses, equipment, devices, and proper body alignment. Patient transfers that are poorly managed are associated with higher fall rates, morbidity, mortality, and healthcare worker injury. A variety of devices, ranging from sling transfers and sliding boards to gait belts and crutches, are available for patients who are weight-bearing or non-weight-bearing or have an impaired gait, muscle weakness, joint problems, or injury. Nurses should use a step-by-step process to gather their supplies and equipment, clearly communicate, guide the patient through all the steps of the movement, and monitor the patient for pain or adverse symptoms. Patient education should include safety measures, maneuver instructions, and signs and symptoms to report to the nurse. Clear communication during patient transfer can ensure patient safety and prevent healthcare worker injury.
9.4 Positioning in Bed
A patient who is immobile in bed for long periods of time is at risk for musculoskeletal complications due to reductions in muscle mass and bone mineral density, improper body alignment, and impairment of other body systems. Equipment and devices, such as specialty mattresses, are designed to offload pressure from pressure points in the body and eliminate friction and shear. Specialty boots and wedges, as well as mattresses and repositioning techniques, relieve and distribute pressure throughout the body and aid in alignment. Common patient positions include prone, lateral, supine, and Fowler’s. Nurses should educate patients and families about the various devices available to provide comfort for the patient. Collaboration with physical and occupational therapists is also beneficial as their expertise is in function and mobility.
9.5 Limited Movement Devices
A bone or soft tissue injury may warrant limiting mobility in a joint or limb. The limitation of movement allows the body to repair the injury without the risk of re-injury, complications, or further damage. Common types of devices include casts, braces, slings, bandages, skeletal traction, and external fixation. Each device has its own appropriate indications when treating injury. Nurses should be proactive in caring for these patients, and provide targeted assessments to recognize and prevent complications.
In certain situations, restraint use may be necessary. Restraints can be physical or chemical. The nurse should always ensure that the least restrictive measure is used, the restraint is used properly, frequent assessments are completed to prevent complications, the environment remains safe for the patient and staff, and the restraint is discontinued as soon as possible. Alternatives such as patient diversion, pain relief, and diversionary techniques can reduce the need for restraints, especially in long-term care settings.


18.4: Writing Functions
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In this section I want to talk about functions again. Functions were introduced in Section 3.5, but you’ve learned a lot about R since then, so we can talk about them in more detail. In particular, I want to show you how to create your own. To stick with the same basic framework that I used to describe loops and conditionals, here’s the syntax that you use to create a function:
FNAME <- function ( ARG1, ARG2, ETC ) {
STATEMENT1
STATEMENT2
ETC
return( VALUE )
}
What this does is create a function with the name FNAME, which has arguments ARG1, ARG2 and so forth. Whenever the function is called, R executes the statements in the curly braces, and then outputs the contents of VALUE to the user. Note, however, that R does not execute the commands inside the function in the workspace. Instead, what it does is create a temporary local environment: all the internal statements in the body of the function are executed there, so they remain invisible to the user. Only the final results in the VALUE are returned to the workspace.
To give a simple example of this, let’s create a function called
quadruple()
which multiplies its inputs by four. In keeping with the approach taken in the rest of the chapter, I’ll use a script to do this:
## --- functionexample.R
quadruple <- function(x) {
y <- x*4
return(y)
}
When we run this script, as follows
source( "./rbook-master/scripts/functionexample.R" )
nothing appears to have happened, but there is a new object created in the workspace called
quadruple
. Not surprisingly, if we ask R to tell us what kind of object it is, it tells us that it is a function:
class( quadruple )
## [1] "function"
And now that we’ve created the
quadruple()
function, we can call it just like any other function And if I want to store the output as a variable, I can do this:
my.var <- quadruple(10)
print(my.var)
## [1] 40
An important thing to recognise here is that the two internal variables that the
quadruple()
function makes use of,
x
and
y
, stay internal. That is, if we inspect the contents of the workspace,
library(lsr)
## Warning: package 'lsr' was built under R version 3.5.2
who()
## -- Name -- -- Class -- -- Size --
## balance numeric 1
## day character 1
## i integer 1
## interest numeric 1
## itng.table table 3 x 4
## month numeric 1
## monthly.multiplier numeric 1
## msg character 1
## my.var numeric 1
## payments numeric 1
## quadruple function
## speaker character 10
## today Date 1
## total.paid numeric 1
## utterance character 10
## w character 1
## W character 1
## w.length integer 1
## words character 7
## x numeric 1
we see everything in our workspace from this chapter including the
quadruple()
function itself, as well as the
my.var
variable that we just created.
Now that we know how to create our own functions in R, it’s probably a good idea to talk a little more about some of the other properties of functions that I’ve been glossing over. To start with, let’s take this opportunity to type the name of the function at the command line without the parentheses:
quadruple
## function (x)
## {
## y <- x * 4
## return(y)
## }
As you can see, when you type the name of a function at the command line, R prints out the underlying source code that we used to define the function in the first place. In the case of the
quadruple()
function, this is quite helpful to us – we can read this code and actually see what the function does. For other functions, this is less helpful, as we saw back in Section 3.5 when we tried typing
citation
rather than
citation()
.
Function arguments revisited
Okay, now that we are starting to get a sense for how functions are constructed, let’s have a look at two, slightly more complicated functions that I’ve created. The source code for these functions is contained within the
functionexample2.R
and
functionexample3.R
scripts. Let’s start by looking at the first one:
## --- functionexample2.R
pow <- function( x, y = 1) {
out <- x^y # raise x to the power y
return( out )
}
and if we type
source("functionexample2.R")
to load the
pow()
function into our workspace, then we can make use of it. As you can see from looking at the code for this function, it has two arguments
x
and
y
, and all it does is raise
x
to the power of
y
. For instance, this command
pow(x=3, y=2)
## [1] 9
calculates the value of 3
2
. The interesting thing about this function isn’t what it does, since R already has has perfectly good mechanisms for calculating powers. Rather, notice that when I defined the function, I specified
y=1
when listing the arguments? That’s the default value for
y
. So if we enter a command without specifying a value for
y
, then the function assumes that we want
y=1
:
pow( x=3 )
## [1] 3
However, since I didn’t specify any default value for
x
when I defined the
pow()
function, we always need to input a value for
x
. If we don’t R will spit out an error message.
So now you know how to specify default values for an argument. The other thing I should point out while I’m on this topic is the use of the
...
argument. The
...
argument is a special construct in R which is only used within functions. It is used as a way of matching against multiple user inputs: in other words,
...
is used as a mechanism to allow the user to enter as many inputs as they like. I won’t talk at all about the low-level details of how this works at all, but I will show you a simple example of a function that makes use of it. To that end, consider the following script:
## --- functionexample3.R
doubleMax <- function( ... ) {
max.val <- max( ... ) # find the largest value in ...
out <- 2 * max.val # double it
return( out )
}
When we type
source("functionexample3.R")
, R creates the
doubleMax()
function. You can type in as many inputs as you like. The
doubleMax()
function identifies the largest value in the inputs, by passing all the user inputs to the
max()
function, and then doubles it. For example:
doubleMax( 1,2,5 )
## [1] 10
There’s more to functions than this
There’s a lot of other details to functions that I’ve hidden in my description in this chapter. Experienced programmers will wonder exactly how the “scoping rules” work in R, 137 or want to know how to use a function to create variables in other environments 138 , or if function objects can be assigned as elements of a list 139 and probably hundreds of other things besides. However, I don’t want to have this discussion get too cluttered with details, so I think it’s best – at least for the purposes of the current book – to stop here.


8.14: The ERP CORE N2pc Experiment
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The following exercise will focus on data from the ERP CORE N2pc experiment. This section will describe the experimental design and event code scheme (see Kappenman et al., 2021 for a detailed description). Example stimuli are shown in Figure 8.5.A. N2pc experiments are typically designed to study how people focus their covert attention onto peripheral stimuli without looking at the stimuli, so participants in this experiment were instructed to maintain gaze on the central fixation point at all times.
The experiment was divided into 8 blocks of 40 trials, and participants were instructed to attend to pink in half the blocks and blue in the other half. The task was to find the square of the attended color (using peripheral vision) and press one of two buttons to indicate whether this square had a gap on the top or on the bottom. Each stimulus array had 1 pink square and 11 black squares on one side, along with 1 blue square and 11 black squares on the other side. Except for these constraints, the stimulus locations varied randomly from trial to trial. Most importantly, pink and blue were always on opposite sides, but we randomized which side contained pink and which side contained blue on each trial. Consequently, participants could not know where to shift attention until a given display appeared.
The N2pc component reflects the focusing of attention onto a visual object and is largest when this object is surrounded by nearby distractors (see review by Luck, 2012). It’s a negative voltage in the N2 latency range (typically from 200-300 ms) at posterior electrode sites, and its distinguishing characteristic is that the negative voltage is larger over the hemisphere contralateral to the attended object. For example, the voltage for left-hemisphere electrodes will typically be more negative when the target is in the right visual field than when it is in the left visual field, whereas the voltage for right-hemisphere electrodes will typically be more negative when the target is in the left visual field than when it is in the right visual field.
To make the N2pc easier to visualize, we typically collapse the data into a contralateral waveform (left hemisphere when the target is on the right averaged with right hemisphere when the target is on the left) and an ipsilateral waveform (left hemisphere when the target is on the left averaged with right hemisphere when the target is on the right). These collapsed waveforms are shown in Figure 8.5.B. You can see that the voltage is more negative (less positive) from ~200-300 ms in the contralateral waveform than in the ipsilateral waveform. This voltage is summed with the other ERP components that are active at the same time, which are mainly positive. Thus, the overall voltage is typically positive in both the contralateral and ipsilateral waveforms, but more negative for contralateral than for ipsilateral. To isolate the N2pc from these other components, we make a contralateral-minus-ipsilateral difference wave, as shown in Figure 8.5.C. This difference wave subtracts away all the nonlateralized components, making it easier to see and quantify the time course of the N2pc component.
The event code scheme is summarized in Table 8.3. You can see that the event code for each stimulus indicates which color was relevant for the current trial block (in the 100s place), which side contained the target square on the current trial (10s place), and whether the gap on the target square was on the top or bottom of the square (1s place). There were also event codes for correct and incorrect responses.
|
Relevant Color for Current Block |
Target Side |
Target Gap Location |
Event Code |
|
|---|---|---|---|---|
|
Stimuli |
Blue |
Left |
Top |
111 |
|
Blue |
Left |
Bottom |
112 |
|
|
Blue |
Right |
Top |
121 |
|
|
Blue |
Right |
Bottom |
122 |
|
|
Pink |
Left |
Top |
211 |
|
|
Pink |
Left |
Bottom |
212 |
|
|
Pink |
Right |
Top |
221 |
|
|
Pink |
Right |
Bottom |
222 |
|
|
Accuracy |
Event Code |
|||
|
Responses |
correct |
201 |
||
|
incorrect |
202 |
The bin descriptor file is located in the Chapter_8 folder (named BDF_N2pc.txt ), and the bin descriptors are shown below. You can see that there are separate bins for left and right targets, irrespective of which color was relevant in the current block and whether the target gap was on the top or the bottom. However, we require a correct response between 200 and 1000 ms after the stimuli.
bin 1
Left Target
.{111;112;211;212}{t<200-1000>201}
bin 2
Right Target
.{121;122;221;222}{t<200-1000>201}


27.4: The Evolutionary History of the Animal Kingdom
Skills to Develop
- Describe the features that characterized the earliest animals and when they appeared on earth
- Explain the significance of the Cambrian period for animal evolution and the changes in animal diversity that took place during that time
- Describe some of the unresolved questions surrounding the Cambrian explosion
- Discuss the implications of mass animal extinctions that have occurred in evolutionary history
Many questions regarding the origins and evolutionary history of the animal kingdom continue to be researched and debated, as new fossil and molecular evidence change prevailing theories. Some of these questions include the following: How long have animals existed on Earth? What were the earliest members of the animal kingdom, and what organism was their common ancestor? While animal diversity increased during the Cambrian period of the Paleozoic era, 530 million years ago, modern fossil evidence suggests that primitive animal species existed much earlier.
Pre-Cambrian Animal Life
The time before the Cambrian period is known as the Ediacaran period (from about 635 million years ago to 543 million years ago), the final period of the late Proterozoic Neoproterozoic Era (Figure \(\PageIndex{1}\)). It is believed that early animal life, termed Ediacaran biota, evolved from protists at this time. Some protest species called choanoflagellates closely resemble the choanocyte cells in the simplest animals, sponges. In addition to their morphological similarity, molecular analyses have revealed similar sequence homologies in their DNA.
The earliest life comprising Ediacaran biota was long believed to include only tiny, sessile, soft-bodied sea creatures. However, recently there has been increasing scientific evidence suggesting that more varied and complex animal species lived during this time, and possibly even before the Ediacaran period.
Fossils believed to represent the oldest animals with hard body parts were recently discovered in South Australia. These sponge-like fossils, named Coronacollina acula , date back as far as 560 million years, and are believed to show the existence of hard body parts and spicules that extended 20–40 cm from the main body (estimated about 5 cm long). Other fossils from the Ediacaran period are shown in Figure \(\PageIndex{2}\).
Another recent fossil discovery may represent the earliest animal species ever found. While the validity of this claim is still under investigation, these primitive fossils appear to be small, one-centimeter long, sponge-like creatures. These fossils from South Australia date back 650 million years, actually placing the putative animal before the great ice age extinction event that marked the transition between the Cryogenian period and the Ediacaran period. Until this discovery, most scientists believed that there was no animal life prior to the Ediacaran period. Many scientists now believe that animals may in fact have evolved during the Cryogenian period.
The Cambrian Explosion of Animal Life
The Cambrian period, occurring between approximately 542–488 million years ago, marks the most rapid evolution of new animal phyla and animal diversity in Earth’s history. It is believed that most of the animal phyla in existence today had their origins during this time, often referred to as the Cambrian explosion (Figure 27.4.3). Echinoderms, mollusks, worms, arthropods, and chordates arose during this period. One of the most dominant species during the Cambrian period was the trilobite, an arthropod that was among the first animals to exhibit a sense of vision (Figure \(\PageIndex{4}\)).
The cause of the Cambrian explosion is still debated. There are many theories that attempt to answer this question. Environmental changes may have created a more suitable environment for animal life. Examples of these changes include rising atmospheric oxygen levels and large increases in oceanic calcium concentrations that preceded the Cambrian period (Figure \(\PageIndex{5}\)). Some scientists believe that an expansive, continental shelf with numerous shallow lagoons or pools provided the necessary living space for larger numbers of different types of animals to co-exist. There is also support for theories that argue that ecological relationships between species, such as changes in the food web, competition for food and space, and predator-prey relationships, were primed to promote a sudden massive coevolution of species. Yet other theories claim genetic and developmental reasons for the Cambrian explosion. The morphological flexibility and complexity of animal development afforded by the evolution of Hox control genes may have provided the necessary opportunities for increases in possible animal morphologies at the time of the Cambrian period. Theories that attempt to explain why the Cambrian explosion happened must be able to provide valid reasons for the massive animal diversification, as well as explain why it happened when it did. There is evidence that both supports and refutes each of the theories described above, and the answer may very well be a combination of these and other theories.
However, unresolved questions about the animal diversification that took place during the Cambrian period remain. For example, we do not understand how the evolution of so many species occurred in such a short period of time. Was there really an “explosion” of life at this particular time? Some scientists question the validity of the this idea, because there is increasing evidence to suggest that more animal life existed prior to the Cambrian period and that other similar species’ so-called explosions (or radiations) occurred later in history as well. Furthermore, the vast diversification of animal species that appears to have begun during the Cambrian period continued well into the following Ordovician period. Despite some of these arguments, most scientists agree that the Cambrian period marked a time of impressively rapid animal evolution and diversification that is unmatched elsewhere during history.
Link to Learning
View an animation of what ocean life may have been like during the Cambrian explosion.
Post-Cambrian Evolution and Mass Extinctions
The periods that followed the Cambrian during the Paleozoic Era are marked by further animal evolution and the emergence of many new orders, families, and species. As animal phyla continued to diversify, new species adapted to new ecological niches. During the Ordovician period, which followed the Cambrian period, plant life first appeared on land. This change allowed formerly aquatic animal species to invade land, feeding directly on plants or decaying vegetation. Continual changes in temperature and moisture throughout the remainder of the Paleozoic Era due to continental plate movements encouraged the development of new adaptations to terrestrial existence in animals, such as limbed appendages in amphibians and epidermal scales in reptiles.
Changes in the environment often create new niches (living spaces) that contribute to rapid speciation and increased diversity. On the other hand, cataclysmic events, such as volcanic eruptions and meteor strikes that obliterate life, can result in devastating losses of diversity. Such periods of mass extinction (Figure \(\PageIndex{6}\)) have occurred repeatedly in the evolutionary record of life, erasing some genetic lines while creating room for others to evolve into the empty niches left behind. The end of the Permian period (and the Paleozoic Era) was marked by the largest mass extinction event in Earth’s history, a loss of roughly 95 percent of the extant species at that time. Some of the dominant phyla in the world’s oceans, such as the trilobites, disappeared completely. On land, the disappearance of some dominant species of Permian reptiles made it possible for a new line of reptiles to emerge, the dinosaurs. The warm and stable climatic conditions of the ensuing Mesozoic Era promoted an explosive diversification of dinosaurs into every conceivable niche in land, air, and water. Plants, too, radiated into new landscapes and empty niches, creating complex communities of producers and consumers, some of which became very large on the abundant food available.
Another mass extinction event occurred at the end of the Cretaceous period, bringing the Mesozoic Era to an end. Skies darkened and temperatures fell as a large meteor impact and tons of volcanic ash blocked incoming sunlight. Plants died, herbivores and carnivores starved, and the mostly cold-blooded dinosaurs ceded their dominance of the landscape to more warm-blooded mammals. In the following Cenozoic Era, mammals radiated into terrestrial and aquatic niches once occupied by dinosaurs, and birds, the warm-blooded offshoots of one line of the ruling reptiles, became aerial specialists. The appearance and dominance of flowering plants in the Cenozoic Era created new niches for insects, as well as for birds and mammals. Changes in animal species diversity during the late Cretaceous and early Cenozoic were also promoted by a dramatic shift in Earth’s geography, as continental plates slid over the crust into their current positions, leaving some animal groups isolated on islands and continents, or separated by mountain ranges or inland seas from other competitors. Early in the Cenozoic, new ecosystems appeared, with the evolution of grasses and coral reefs. Late in the Cenozoic, further extinctions followed by speciation occurred during ice ages that covered high latitudes with ice and then retreated, leaving new open spaces for colonization.
Career Connection: Paleontologist
Natural history museums contain the fossil casts of extinct animals and information about how these animals evolved, lived, and died.  They use fossils to observe and explain how life evolved on Earth and how species interacted with each other and with the environment. A paleontologist needs to be knowledgeable in biology, ecology, chemistry, geology, and many other scientific disciplines. A paleontologist’s work may involve field studies: searching for and studying fossils. In addition to digging for and finding fossils, paleontologists also prepare fossils for further study and analysis. Although dinosaurs are probably the first animals that come to mind when thinking about paleontology, paleontologists study everything from plant life, fungi, and fish to sea animals and birds.
An undergraduate degree in earth science or biology is a good place to start toward the career path of becoming a paleontologist. Most often, a graduate degree is necessary. Additionally, work experience in a museum or in a paleontology lab is useful.
Summary
The most rapid diversification and evolution of animal species in all of history occurred during the Cambrian period of the Paleozoic Era, a phenomenon known as the Cambrian explosion. Until recently, scientists believed that there were only very few tiny and simplistic animal species in existence before this period. However, recent fossil discoveries have revealed that additional, larger, and more complex animals existed during the Ediacaran period, and even possibly earlier, during the Cryogenian period. Still, the Cambrian period undoubtedly witnessed the emergence of the majority of animal phyla that we know today, although many questions remain unresolved about this historical phenomenon.
The remainder of the Paleozoic Era is marked by the growing appearance of new classes, families, and species, and the early colonization of land by certain marine animals. The evolutionary history of animals is also marked by numerous major extinction events, each of which wiped out a majority of extant species. Some species of most animal phyla survived these extinctions, allowing the phyla to persist and continue to evolve into species that we see today.
Glossary
- Cambrian explosion
- time during the Cambrian period (542–488 million years ago) when most of the animal phyla in existence today evolved
- Cryogenian period
- geologic period (850–630 million years ago) characterized by a very cold global climate
- Ediacaran period
- geological period (630–542 million years ago) when the oldest definite multicellular organisms with tissues evolved
- mass extinction
- event that wipes out the majority of species within a relatively short geological time period


3.4: Summary
3.1 Therapeutic Communication
The process of therapeutic communication in nursing consists of several steps: develop communication goals, create the message, deliver the message, listen to the response, and seek clarification of the response. The primary characteristics of therapeutic communication are building trust through honesty, active listening , and respecting patients’ beliefs and values. To evaluate therapeutic communication, one must reflect on the patient’s response and compare the response to the desired communication goals.
3.2 Comprehensive Interview Practices
The four phases of a comprehensive interview are the preparatory phase , the introductory phase , the maintenance phase , and the termination phase . The best techniques the nurse can use during a comprehensive interview help the patient to answer questions without interrupting their flow of ideas; these techniques include asking open-ended questions, adaptive questioning , encouraging the patient to verbalize their feelings, and respecting the patient’s values and beliefs. Finally, there are special considerations to recognize when conducting a comprehensive interview: age, cultural, and emotional issues can all add complex factors that nurses must take into consideration.
3.3 Patient Education and Teaching
The purposes of patient education and teaching are to promote positive patient outcomes, health literacy , and self-care. Many factors can affect patient learning, including the patient’s learning needs, age and developmental level, and readiness to learn. The nurse’s role in patient education and teaching involves determining effective teaching strategies, evaluating patient learning, and documenting the teaching-learning process.


15.11A: Overview of Pancreatic Islets
Pancreatic islets, also called the islets of Langerhans, are regions of the pancreas that contain its hormone-producing endocrine cells.
- Differentiate among the types of pancreatic islet cells
Key Points
- The pancreatic islets are small islands of cells that produce hormones that regulate blood glucose levels. Hormones produced in the pancreatic islets are secreted directly into the bloodstream by five different types of cells.
- The alpha cells produce glucagon, and make up 15–20% of total islet cells. The beta cells produce insulin and amylin, and make up 65–80% of the total islet cells. The delta cells produce somatostatin, and make up 3–10% of the total islet cells.
- The gamma cells produce pancreatic polypeptide, and make up 3–5% of the total islet cells. The epsilon cells produce ghrelin, and make up less than 1% of the total islet cells.
- The feedback system of the pancreatic islets is paracrine, and is based on the activation and inhibition of the islet cells by the endocrine hormones produced in the islets.
Key Terms
- endocrine : Produces internal secretions that are transported around the body by the bloodstream.
- paracrine : Describes a hormone or other secretion released from endocrine cells into the surrounding tissue rather than into the bloodstream.
- exocrine : Produces external secretions that are released through a duct.
The pancreas serves two functions, endocrine and exocrine. The exocrine function of the pancreas is involved in digestion, and these associated structures are known as the pancreatic acini.
The pancreatic acini are clusters of cells that produce digestive enzymes and secretions and make up the bulk of the pancreas. The endocrine function of the pancreas helps maintain blood glucose levels, and the structures involved are known as the pancreatic islets, or the islets of Langerhans.
Pancreatic islets or islets of Langerhans : The islets of Langerhans are the regions of the pancreas that contain its endocrine (hormone-producing) cells.
The pancreatic islets are small islands of cells that produce hormones that regulate blood glucose levels. Hormones produced in the pancreatic islets are secreted directly into the blood flow by five different types of cells.
Pancreatic tissue : The small cells in the middle are beta cells, and the surrounding larger cells are alpha, delta, gamma, and epsilon cells.
The endocrine cell subsets are:
- Alpha cells that produce glucagon and make up 15–20% of total islet cells. Glucagon is a hormone that raises blood glucose levels by stimulating the liver to convert its glycogen into glucose.
- Beta cells that produce insulin and amylin and make up 65–80% of the total islet cells. Insulin lowers blood glucose levels by stimulating cells to take up glucose out of the blood stream. Amylin slows gastric emptying, preventing spikes in blood glucose levels.
- Delta cells that produce somatostatin and make up 3–10% of the total islet cells. Somatostatin is a hormone that suppresses the release of the other hormones made in the pancreas.
- Gamma cells that produce pancreatic polypeptide and make up 3–5% of the total islet cells. Pancreatic polypeptide regulates both the endocrine and exocrine pancreatic secretions.
- Epsilon cells that produce ghrelin and make up less than 1% of the total islet cells. Ghrelin is a protein that stimulates hunger.
The feedback system of the pancreatic islets is paracrine—it is based on the activation and inhibition of the islet cells by the endocrine hormones produced in the islets. Insulin activates beta cells and inhibits alpha cells, while glucagon activates alpha cells, which activates beta cells and delta cells. Somatostatin inhibits the activity of alpha cells and beta cells.


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8.1: Nucleotides -the building blocks of nucleic acids
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Nucleic acids are defined, and their constituents and related terminologies are described.
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8.2: Primary structure of deoxyribonucleic acid (DNA)
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The definition, synthesis mechanism, and primary structure of nucleic acids are described.
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8.3: Secondary structure and replication of DNA
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Watson and Crick's double helix model and DNA replication process are described.
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8.4: Ribonucleic acid (RNA) and transcription
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RNAs involved in protein synthesis, i.e., mRNA, tRNA, rRNA, their basic structure feature and functions, along with the process of transcription, codon, and anticodons, are described.
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8.5: Translation-Protein Synthesis
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The biological translation is defined, and its mechanism is explained.
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8.6: Mutations and Genetic Diseases
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Mutation, causes, subclasses, and effects, including genetic diseases and cancer, are described.
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8.7: Viruses
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Viruses, their ways of infection, multiplication, and two example cases, covid-19 and AIDS are described.
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8.8: Genetic engineering
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Recombinant DNA and PCR techniques and their applications in biomedical technologies are described.


11: Safety
Student Learning Outcomes
After reading this chapter, you should be able to:
- Describe the difference between acute and chronic health effects as they relate to safety
- List the various types of safety practices of a water utility
- Explain the importance of proper record keeping related to safety
Safety in the workplace is something that transcends all industries. Each profession has their own set of safe work practices as it pertains to their specific job functions. For example, construction workers might be exposed to excessive heat. Therefore, these employees should be given the proper training and equipment to help prevent things like heat stroke. People working on an assembly line might be exposed to repetitive motions, which can lead to things like carpal tunnel syndrome. Their employer must provide the right work conditions in order to protect against strains and conditions associated with this type of activity. Another example might be someone working on a loading dock and is required to lift heavy objects. In this case, they must receive the proper instructions on how to lift properly and provided about what to do in the case where something is too heavy to lift.
These are just a few examples of safety-related items workers encounter in various industries. The water utility industry is no different. In fact, a professional water worker might be exposed to many different safety-related issues compared to employees in other industries. In addition, since many water utility operators are required to work around the public, there is an aspect of protecting the public from injuries related to the work they do. This text will attempt to analyze and address many of the safety items water workers might encounter.
Various Types of Safety
We will break the different types of safety into three (3) main categories. These are organizational safety, fleet safety, and public safety. Each of these categories is defined below:
- Organizational Safety—This is the most universal type of safety businesses (organizations) are faced with. It is the overall prevention of injury to employees. This prevention of injury is for employees both on and off the job. You might ask why an employer should be concerned with an employee’s personal safety when they are not working. The main reason organizations should instill the value of safety for employees both on and off the job is two-fold. First, any injury can result in lost time. This means if an employee gets injured at home, they may not be able to report to work. This results in inefficiency in the workplace and sometimes results in a loss of revenue for the employer. The second reason and maybe more importantly is creating a culture where safety is a value within the organization. Valuing safe work practices both on and off the job will result in a safer work environment and less loss time and money for organizations.
- Fleet Safety—Water utility workers work within a community. They are required to operate equipment and drive vehicles. This can result in traffic accidents and equipment-related accidents. Fleet safety is designed to help prevent these types of accidents.
- Public Safety—Put simply, public safety is the prevention of injury to the general public. Water utilities have facilities throughout a community and it is important these facilities do not pose a safety hazard to the general public. An example of this might be something simple like a meter box lid. If the lid is missing or broken, it could present a tripping hazard to someone walking along a sidewalk. Water utility workers also work in public streets. This not only presents a safety hazard to the employee but blocking off portions of a street can lead to traffic accidents and exposes the public to potential safety hazards.
Organizing a Safety Program
Each utility should designate an individual responsible for safety. Unfortunately in smaller agencies this is usually someone in middle management. A full-time safety officer is important in order to have one single person looking after health and safety for the entire organization. When safety is assigned to someone with other responsibilities, safety sometimes gets overlooked. Regardless who is tasked with overseeing the program, it is important that staff, management, and the entire organization look at safety as a core value. Each individual is ultimately responsible for their own safety, but they also need the correct tools and equipment to do their job safely.
A designated safety’s main responsibility is to help staff and primarily supervisors. They are not tasked with providing all the training and equipment. They are to assess safety work practices and help implement safety programs. They determine the safety needs of an organization. They plan, develop, and recommend safety plans and programs. A safety officer should evaluate the effectiveness of safety plans and programs and make adjustments and corrections as necessary. Generating safety information and conducting meetings with employees and supervisors is also a function of a safety officer. Investigating accidents and injuries is also part of the responsibility of a safety officer as well as maintain records and reports covering all aspects of the safety program. These are some of the more critical responsibilities and additional tasks may be required as necessary.
Management also plays a large role in regards to safety. Without management’s “buy-in”, staff sometimes feels disenfranchised. Management needs to establish an overall safety policy for the organization. They appoint the safety officer (or coordinator) and assign responsibility for accident prevention. Management establishes goals, revises as needed, and evaluates results of the overall program.
Supervisors set the patterns for safety and should lead by example. No employee likes the “do as I say, not as I do” attitude. Since supervisors have direct control over employees, they should instill safety as a core value and provide the proper tools, equipment, and safety items needed to do tasks in a safe manner. They should instruct and council staff on safe work habits and review work for compliance with the safety program and regulations.
Employees are the front line workers of an organization. Therefore they are typically exposed to the majority of safety hazards. They must perform their work in accordance with the appropriate safety procedures and actively participate in the safety program. All injuries and hazards should be reported. At no time should an employee work in an unsafe manner or condition. If an employee feels a job is unsafe they are to report these findings to a supervisor.
The following is an example policy safety statement:
- The organization’s recognition of the need for safety in order to stimulate efficiency, improve service, build employee morale, and promote better public relations
- The organization’s interest in the employee - to provide proper equipment and working conditions, and to promote safety and the expectation that the individual employee will maintain safe work practices
- The fact that the human factor rather than the mechanical is most significant cause of accidents, thus emphasizing the employee’s responsibility to perform the job safely
- That an essential part of the supervisor’s job is responsibility for development of safe work practices and their environment
Safety Regulatory Requirements
The federal Occupational Safety and Health Administration (OSHA) is responsible for assuring safe and healthful working conditions by setting and enforcing standards and by providing training, outreach, education, and assistance. OSHA is part of the United States Department of Labor. Safe work practices can eliminate and reduce suffering, injury, and death. Safe work practices also reduce lost time, medical costs, and legal judgments. Proper safe work practices save time and money for companies too.
OSHA has established minimum health and safety standards that are applicable to every industry. The mandate that every employer furnish employees with a workplace that is free from recognized hazards that are likely to cause death or serious physical harm.
Causes of Accidents
Unsafe acts and unsafe conditions are two of the most common results in accidents and injuries. Lack of experience or improper training commonly results in unsafe acts. Some employees have an indifference to safety and can result in excess accidents and injuries. Poor work habits or cutting corners, working too fast and impatience results in unnecessary accidents and injuries. It is also important for employees to be well-rested and in good physical condition. There are usually specific condition requirements for some jobs. For example, a job requiring the operation of heavy equipment or strenuous labor may require certain licenses and regular physical fitness testing. Drug and alcohol testing may also be required for certain jobs. Impaired employees pose a danger to themselves and to other co-workers. Below are examples of unsafe acts:
- Ignorance—It is not that employees are ignorant. It is when they lack the experience or training to do their job safely
- Indifference—Some employees and in some instances employers are “indifferent” or do not care about safe work practices
- Poor work habits—Many times employees develop bad habits if they don’t understand how to perform task correctly in the first place
- Laziness—Sometimes employees do not want to or are unable to provide the required effort
- Haste—Working too fast can contribute to unsafe work conditions
- Poor physical condition—Employees need to have proper rest and for some tasks must be physically fit
- Temper—Impatience and anger can cloud judgment and result in accidents
Reading through the list above you might have thought that most if not all of these are preventable. If so, you would be right. Most unsafe acts and conditions are preventable. That is not to say all accidents can be avoided, but many can by simply avoiding the list above.
Safety Training Topics
One of the most important aspects of a safety program is training the workforce. Some training topics are required to be completed by employees on a routine basis. Standard training requirements are found in Occupational Safety and Health Administration (OSHA) regulations. Some safety requirements are under General Industry standards while others are specific based on the type of industry. The following safety training topics are general in nature, required throughout the water industry, and provide a high level of understanding.
Hazard Communication
Any industry where chemicals are used, annual training explaining the hazards associated with exposure to these chemicals in the workplace must be conducted. Employers should provide employees with training prior to initial assignment to their work area. Hazard communication (HazComm) training should identify the activities and locations of the chemicals in the workplace and the health hazards associated with exposure to the chemicals. Additional topics covered in the training include but are not limited to steps employees can take to protect themselves, labeling criteria of the chemicals. And clean up procedures.
As part of hazard communication training, an inventory list of chemicals needs to be provided and available to all employees. The details of which chemicals are required to be covered in training are beyond the details provided in this text. The example we will use is one of the more common chemicals used in the water industry. Chlorine is one of the most widespread chemicals used in drinking water distribution and treatment. In addition, chlorine is hazardous to health.
Several different types of chlorine related compounds are used in the disinfection of drinking water. Calcium hypochlorite is corrosive in water and can support combustion. Sodium hypochlorite is a very strong base on its own and becomes an acid in water. Operators should wear goggles and gloves when working with hypochlorites.
The most common disinfectant in drinking water is chlorine, which is a greenish/yellow gas. Since chlorine gas is two and half times heavier than air, ventilation is required in chlorine rooms. The ventilation vents should be twelve (12) inches above the floor. Since chlorine is a compressed gas and stored in cylinders, it should not be filled more than eighty-five (85) percent to allow for expansion. Another safety feature of chlorine gas cylinders is a fusible plug. One (1) ton cylinders have two (2) valves for removing either gas or liquid and six (6) fusible plugs. A one hundred fifty (150) pound cylinder has one of each. Fusible plugs are designed to melt between the temperatures of one hundred fifty-eight (158) and one hundred sixty-five (165) degrees Fahrenheit. If there are chlorine leaks in a cylinder, an ammonia-soaked rag can be used to help detect the leak. By waving an ammonia-soaked rag a white cloud would appear. High levels of chlorine in the air affect respiration and the immediately dangerous to life and health (IDLH) level is 10 parts per million (ppm).
This example is just one of many where chemicals are used in the workplace and employees need to be properly trained on the hazards associated with working with and around these chemicals. In 2003, the United Nations adopted the Globally Harmonized System of Classification and Labeling of Chemicals (GHS). In 2009, OSHA published regulations to align their Hazard Communication standard (HCS) with the GHS. There are five (5) mandatory components of OSHA’s HCS, one of which includes an update to what was previously known as Material Safety Data S, which sheets. The revised standard refers to Safety Data Sheets (STS) and sixteen (16) required sections with information about each chemical. If there is no relevant information under one of the subject headings, then the SDS must clearly indicate that no applicable information is available.
Personal Protective Equipment
One of the sections on an SDS must reference personal protection from exposure to chemicals. In addition, personal protective equipment (PPE) has its own regulatory standards regarding training, what types of working conditions might require PPE, and how to Don, Doff, and care for PPE.
Each employee is responsible to maintain their own PPE and notify their supervisor whenever it needs replacing. It is the management’s responsibility to provide the training and required PPE needed by the employees. The following PPE examples are just some common types of personal protective equipment.
- Hard hats—Any time there is a potential for head injuries including low headroom working conditions or overhead items, which can fall on an employee, hard hats are required. Metal or plastic hard hats can be used, but metal hard hats should not be used where there are electrical hazards.
- Gloves—If there are pinching, cutting, crushing, or other hand-related injuries, then gloves should be worn. In addition, gloves may also be required when working with or around chemicals.
- Respiratory—When surrounding air contains dust, fumes, mists, or any other particulates, which can be inhaled, then respiratory protection is required. Respiratory protection can be as simple as a dust mask or as complex as a self-contained breathing apparatus.
- Eye Protection—Goggles, face shields, safety glasses are all forms of eye protection. Dust and debris can cause irritation is they get into someone’s eyes. Any kind of object, including chemicals, can all cause damage to the eye.
- Steel-toed boats—It is prudent to wear foot protection in any construction-related industry. Therefore, steel-toed boats are often required.
- Hearing Protection—Earplugs provide ear protection from loud noises and sounds. Earmuffs can also be used to protect ears.
Understanding how to don and doff PPE is an important aspect of PPE training and all employees should understand the proper way to wear the appropriate equipment.
Slips Trips and Falls
Sometimes, the simplest and most common hazards can result in personal injury. Slips, trips, and falls should always be avoidable. Often times, it is a matter of good housekeeping. Making sure floors and walking surfaces are clear of debris and any kind of slipping or tripping hazards. Walking areas should have slip-resistant surfaces and proper handrails should be provided on stairways, catwalks, and areas where walking can be difficult. Fall protection also needs to be provided on elevated surfaces.
Back Safety
Back injuries are one of the most common injuries in the workplace. Improper lifting, twisting, pulling, and pushing are all aspects of back safety. Whenever lifting something heavy, workers should always bend at the knees and keep their back straight. One person should never lift large and heavy loads. When carrying something heavy, you should always turn with your legs and not at your waist. Equipment should also be used when appropriate to help lift and/or move heavy objects.
Trench Safety
Trenching is a method of digging into the ground to install things such as pipes. Whenever work is done inside a trench, special precautions need to be made in order to protect workers from the possibility of a cave-in. There are specific requirements based on the depth of the trench. If trenches are shallow (less than five (5) feet) then the danger is not as great as it is with deeper trenches. However, workers can still get trapped in shallow trenches. When trenches are five (5) feet or deeper, special protection is required. This protection is referred to as shoring, shielding, or sloping. If there is enough room, then sloping is allowed. Sloping is the process of reducing the depth of a trench by removing soil and opening the width of a trench to prevent the trench walls from collapsing. Shoring and shielding is the process of using equipment placed up against trench walls. The dirt being excavated (referred to as spoils) should be placed at least two (2) feet away from the trench edge and on the side opposite of the pipe being installed. If trenches are long, then ladders should be placed within twenty-five (25) feet of workers. Another important aspect of trench safety is proper supervision. Special training must be provided to individuals overseeing trenching activities. These individuals providing supervision are referred to as a “Competent Person”.
Confined Spaces
A confined space is defined, as a workspace, which has limited or restricted means of entry or exit, is large enough for an employee to enter and perform work, and is not designed for continuous work or occupancy. Confined spaces are defined as “permit-required” and “non-permit required” confined spaces. In order for a confined space to be classified as a permit-required confined space, it must meet the following conditions:
- Contains or has the potential to contain a hazardous atmosphere
- Contains a material that has the potential for engulfing an entrant
- Has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls or by a floor that slopes downward and tapers to a smaller cross-section
- Contains any other recognized serious safety or health hazard
The internal atmosphere of a confined space must be tested for oxygen content, flammable gases, and vapors, potentially toxic air contaminants, hydrogen sulfide, and methane. Ventilation equipment should be used to provide acceptable air conditions. Three (3) or more workers should be involved with permit-required confined spaces. One (1) or more workers inside the confined space, one (1) worker in communication with the worker(s), and one (1) worker to respond and retrieve emergency personnel if needed.
Respiratory Safety
As previously mentioned, it is important to provide workers with respiratory protection if the surrounding atmosphere is not adequate for a working environment. Respiratory hazards include, but are not limited:
- Dust from rock, cement, coal, and wood
- Dust from toxic materials such as lead, arsenic, and asbestos
- Mists and fumes from chemicals and heated materials
- Vapors and gases from chemicals such as chlorine, ammonia, and carbon monoxide
- Oxygen deficient environments
Respiratory problems can range from very mild irritation causing coughing and wheezing, to death. Respirators can be broken down into two main types, air purifying and atmosphere supplying.
Air-purifying—These types of respirators use cartridges, filters, or canisters to remove contaminants from the air. In order to remove vapors and gases, a granular porous material referred to as an absorbent needs to be used. The type of filter, cartridge, or canister is dependent on the type and amount of the airborne contaminate. For example, a particulate filter would not necessarily remove vapors or gases. Therefore the employer must identify the contaminant(s) and provide employees the proper protection against dust, fumes, mists, and solid particulate matter.
Atmosphere-supplying—In certain circumstances, the surrounding atmosphere is not suitable for breathing and purifying the air may not be sufficient. Therefore, a respirator where clean air is provided should be used. A common situation where this might occur is when the surrounding atmosphere lacks adequate oxygen levels or is considered oxygen deficient. At this point, atmosphere-supplying respirators are required.
There are a number of various other safety topics, which should be considered if potential hazards exist. Some of these topics include, but are not limited to hand and power tool safety, electrical, head, body, and extremity protection.
Traffic Control
Utility workers often work in roadways. Whenever work is performed in traffic areas, the Manual on Uniform Traffic Control Devices for Streets and Highways should be used. This manual is published by the US Department of Transportation (USDOT) and specifies approved traffic control devices and procedures. Some states have their own traffic control reference manuals and those should also be reviewed before working in the street. If improper traffic control is set up, the utility can be held liable for damage from accidents. Often times special permits, such as encroachment permits are required as well as special traffic control plans need to be submitted to the governing agency. Traffic control devices such as cones, pylons, and other systems are used to channel the flow of traffic to designated areas. There are five (5) zones within a construction worksite in roadways:
- Advanced Warning Zone—This area is a warning to drivers letting them know what to expect. This advanced warning can be as simple as a single flashing light to a series of signs and notifications prior to the temporary construction work and change in the flow of traffic.
- Transition Zone—Whenever the redirection of the normal flow of traffic is required, a transition area is needed. Traffic must be channelized from the normal flow to the new path in order to avoid the construction area.
- Buffer Zone—While not required, it is an important area for the protection of workers. It is an area between the flow of oncoming traffic and the area where employees are working.
- Work Zone—This is the area where the work is being performed. Workers and equipment are within this area. By the time traffic reaches this area, it should be completely redirected out of this zone.
- Termination Zone—As with the transition zone, the termination zone is redirecting traffic. Except in this zone, traffic is being returned to its normal flow path.
The taper lengths and buffer zones have specific distances in relation to traffic speed. More traffic control devices, longer taper lengths, and larger buffer zones are needed as the speed of traffic increases.
Occupational Injuries
All injuries in the workplace should be reported immediately. This early reporting not only helps the utility determine if the injury occurred at work and it also speeds up the process for the employee to start any type of worker’s compensation. An occupation injury is defined as any personal injury sustained by an employee during the course of work. Employees should report their injury to their supervisor or to the organization's safety representative. Utilities typically have injury report forms. These forms should be simple but informative. They should contain information from both the employee and supervisor. The employee is responsible for reporting the injury and the supervisor and safety representative are responsible for making sure the report form is completed correctly.
All injuries should be investigated. Accident and injury investigations provide an opportunity for the safety professional to speak with the employee and any witnesses. It allows for feedback on the cause of the incident and give the safety professional the opportunity to provide feedback on the necessity of exercising care and caution. It also presents the opportunity to identify any unsafe work practices or conditions and allows for recommendations on workplace improvements.
Safety professionals should prepare and review a variety of reports associated with workplace accidents and injuries. These include, but are not limited:
- Number of lost-time injuries—any injuries resulting employees missing time from work
- Number of injuries requiring first aid—first aid kits should be provided at each workplace and with workers who work in remote locations
- Number of injuries requiring medical attention—any injury where an employee receives assistance from a medical professional
- Number of lost time days—when employees miss work due to an injury, this is referred to as lost time
There are also OSHA related performance measures safety professionals use to track and interpret the prevalence of workplace-related injuries. These include:
- Incidence Rate—This is based on the number of injuries requiring more than first aid per 200,000 hours worked
- Frequency Rate—This is the number of lost time accidents per million employee hours worked
- Severity Rate—This is the number of days lost or charged per million employee hours worked
OSHA has specific reporting requirements related to workplace injuries. Most organizations are required to maintain an OSHA Form 300 Log. This log lists all recordable workplace injury and illness. OSHA defines a recordable injury or illness as:
- Any work-related fatality
- Any work-related injury or illness that results in loss of consciousness, days away from work, restricted work, or transfer to another job
- Any work-related injury or illness requiring medical treatment beyond first aid
- Any work-related diagnosed case of cancer, chronic irreversible diseases, fractured or cracked bones or teeth, and punctured eardrums
In addition to these definitions, there are also special recording criteria for work-related cases involving: needle sticks and sharps injuries; medical removal; hearing loss; and tuberculosis. In general, minor injuries and injuries requiring first aid treatment do not need to be recorded. All employers are also required to notify OSHA directly when an employee is killed on the job or suffers a work-related hospitalization, amputation, or loss of an eye. Fatalities must be reported within eight (8) hours and in-patient hospitalization, amputation, or eye loss must be reported within twenty-four (24) hours.
Safety is a very important aspect for all occupations. Water utility operations are no exception. It is important for safety to be supported from the top executives all the way down throughout the organization. Ultimately, the primary person responsible for safety is…YOU!
Sample Questions
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When symptoms develop rapidly within a person it is considered ___________.
- A chronic health effect
- An acute health effect
- A disease
- Both 1 and 3
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What is the primary responsibility of the safety officer?
- Should be a line function
- Should be a staff function
- Should provide all the training
- All of the above
-
Traffic control should be set up in the following order:
- Buffer Zone, Transition Zone, Work Zone, Termination Zone, Advanced Warning
- Advanced Warning, Buffer Zone, Work Zone, Transition Zone, Termination Zone
- Advanced Warning, Transition Zone, Buffer Zone, Termination Zone, Work Zone
- Advanced Warning, Transition Zone, Buffer Zone, Work Zone, Termination Zone
-
Fusible plugs are designed to ___________.
- Melt, preventing combustion
- Melt between 158°F - 165°F
- Fuse the valve connection to the hose
- Only 1 and 2
-
A 1-ton chlorine cylinder has ___________.
- 2 fusible plugs and 6 valves
- 2 valves and 6 fusible plugs
- 1 valve and 5 fusible plugs
- 5 valves and 1 fusible plug
-
The IDLH for chlorine gas is ___________.
- 5 ppm
- 10 ppm
- 20 ppm
- 100 ppm
-
All fatalities, serious injuries and illnesses must be reported to Cal/OSHA within ___________.
- 8 hours
- 16 hours
- 24 hours
- 48 hours
-
A chronic health effect is ___________.
- An adverse effect developing rapidly
- An adverse effect resulting in cancer
- An adverse effect developing over a long period of time
- A disease with little or no symptoms