Air: Pure air is mixture of gasses containing approximately 78% nitrogen, 21% oxygen and less than 1% carbon dioxide and other gasses.
Air Quality Index (AQI): A unit of measurement to report on the severity of pollution in the air.
Allergen: A substance capable of causing an allergic reaction because of an individual's sensitivity to that substance.
Clean Air Delivery Rate (CADR): It is the fraction of particles (of a particular size distribution) that have been removed from the air, multiplied by the air flow rate (in CFM) through the device. Hence, you may have a different CADR smoke, pollen, and dust.
High Efficiency Particulate Air (HEPA): HEPA filters capture variously sized particles within a multi-layered netting usually made out of very fine fiberglass threads
Indoor air quality (IAQ): The air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants.
Micron: A micron is one-millionth of a metre or one twenty-five thousandth of an inch.
Parts per million (PPM): The number of units of mass of a contaminant per million units of total mass.
Particulate Matter (PM): Solid or liquid particles of soot, dust, smoke, fumes, and aerosols.
Particulate Matter less than 10 microns (PM10): Tiny solid or liquid particles of soot, dust, smoke, fumes, and aerosols. The size of the particles (10 microns or smaller) allows them to easily enter the air sacs in the lungs where they may be deposited and result in adverse health effects. PM10 also causes visibility reduction and is a criteria air pollutant.
Particulate Matter equal or less than 2.5 microns (PM2.5): Ultra-fine particles, or PM2.5, pose an increased health risk over PM10 because PM2.5 can deposit deep in the lung and contain substances that are particularly harmful to human health.
Volatile Organic Compounds (VOCs): Compounds that vaporize (become a gas) at room temperature. Common sources include housekeeping and maintenance products, and building and furnishing materials.