The quality of the air we breathe impacts our health. Breathing polluted air can cause health problems ranging from watery eyes and cough, to worsening asthma, heart attack and stroke.
Particle pollution, also call Particulate Matter (PM) is a mixture of particles (tiny pieces) of solids and liquids in the air, such as ash, vehicle exhaust, and soil dust. These particles come in different sizes, from larger, course particles, to smaller, fine and ultrafine particles. Fine particles that are less than 2.5 microns in diameter are called PM2.5.
Under the Clean Air Act, EPA sets and reviews national air quality standards for PM. Air quality monitors measure concentrations of PM throughout the country. EPA, state, tribal and local agencies use that data to ensure that PM in the air is at levels that protect public health and the environment.