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.
A micrometer generally provides greater precision than a caliper, but is limited to a smaller range of lengths. For example, it would take a six-piece set of micrometers to cover the range of a 6 caliper. Parts of an Outside Micrometer. Proper Use and Care for a Micrometer.