Bioaerosols are airborne microorganisms or biological particles, living or originating from living organisms, that are naturally present in the environment.

BTU (British Thermal Unit) measures the energy an air conditioning system uses to transfer heat. One BTU is the energy needed to change the temperature of one pound of water by one degree Fahrenheit.

BTUH, or British Thermal Units per Hour, measures the cooling capacity of an air conditioner. It indicates how much heat the unit can remove from a space each hour.