The standard sets a permissible exposure limit (PEL) of 25 parts methylene chloride per million parts of air (ppm) as an eight-hour time-weighted average (TWA). This refers to the average exposure during an eight-hour period. Employers must use engineering and work practice controls to limit employee exposures.
The state of the atmosphere at a particular time and place. Weather is described in terms of variable conditions such as temperature, humidity, wind velocity, precipitation, and barometric pressure. Weather on Earth occurs primarily in the troposphere, or lower atmosphere, and is driven by energy from the Sun and the rotation of the Earth. The average weather conditions of a region over time are used to define a region's climate.
Key Difference: Weather is the state or conditions of the atmosphere over a short period of time, usually a day or so. Weather and climate are words that are often heard in meteorology, while weather is also used in day to day in order to refer to the conditions outside. Weather and climate are similar, but different. The main difference between the two is weather changes day to day, while climate does not change for longer periods of day. Weather is the state or conditions of the atmosphere over a short period of time, usually a day or so. The weather changes day to day and forecasting must be done continuously in order to determine the sudden changes in the weather.