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.
The term fine particles, or particulate matter 2.5 (PM 2.5), refers to tiny particles or droplets in the air that are two and one half microns or less in width. Like inches, meters and miles, a micron is a unit of measurement for distance.There are about 25,000 microns in an inch.The widths of the larger particles in the PM 2.5 size range would be about thirty times smaller than that of a human hair.ike inches, meters and miles, a micron is a unit of measurement for distance. There are about 25,000 microns in an inch. The widths of the larger particles in the PM 2.5 size range would be about thirty times smaller than that of a human hair.