Particulate matter (PM) consists of tiny solid particles and liquid droplets suspended in air that originate from combustion, dust, pollen, and industrial processes. These particles vary in size and composition, affecting how deeply they penetrate the respiratory system. The EPA regulates PM10 (particles 10 micrometers or smaller) and PM2.5 (particles 2.5 micrometers or smaller).
Sources and Composition
Indoor and outdoor sources include vehicle emissions, power plants, manufacturing facilities, dust, pet dander, and cooking activities. PM10 settles more quickly but PM2.5 remains airborne for extended periods. Long-term exposure to particulate matter correlates with cardiovascular and respiratory diseases.
HVAC Filtration and Control
MERV ratings from 8 to 16 effectively capture various particle sizes in HVAC systems. High-efficiency particulate air (HEPA) filters remove 99.97% of particles 0.3 micrometers and larger. Regular filter replacement every 1 to 3 months, depending on conditions, maintains system efficiency. Proper ventilation and air cleaning devices reduce indoor PM concentrations and improve occupant health.