A fire marshal, in the United States and Canada, is often a member of a fire department but may be part of a building department or a separate department altogether.
An average human red blood cell is approximately 5 microns in diameter. The average diameter of human hair is roughly 0.0035 inches in diameter, which is equivalent to 75 microns. The abbreviation micron was initially used to distinguish the units of a tool used to measure small distances, also called a micrometer.
Micrometers are typically used in manufacturing, machining, and mechanical engineering. There are three types of micrometer: outside, inside, and depth. Outside micrometers may also be called micrometer calipers, and are used to measure the length, width, or outside diameter of an object. Inside micrometers are typically used to measure interior diameter, as in a hole. Depth micrometers measure the height, or depth, of any shape that has a step, groove, or slot.