Particulates
Particulates, or tiny airborne particles, include combustion products, dust and pollen. Indoor sources include fireplaces, wood stoves, kerosene heaters and unvented gas space heaters, air fresheners, candles, and improper cleaning and vacuuming. Biological particles can come from indoor or outdoor sources and may include animal (pet dander) and insect allergens, viruses, bacteria and molds, pollen and plant particles which can cause allergic reactions or infectious diseases. Outdoor sources include wildfires, dusts, agricultural operations, fuel combustion, transportation and industrial emissions.
Health effects depend on the size, types and concentrations of particles inhaled, the frequency and duration of exposure, and individual sensitivity. Health effects can range from irritation of the eyes and/or respiratory tissues to more serious effects, such as cancer and decreased lung function. Large, visible dust particles quickly settle from the air, and if inhaled deposit in the upper airways. Smaller invisible particles, known as respirable particles, stay airborne for long time periods. If respirable particles are inhaled, they deposit in the lower air-exchange regions of the lungs, where they can do more damage.