solid or liquid particles found in the air with a diameter of 10 micrometers or less (0.0004 inches or one-seventh the width of a human hair). EPA's health-based national air quality standard for PM-10 is 50 µg/m3 (measured as an annual mean) and 150 µg/m3 (measured as a daily concentration). Particulate matter 2.5 micrometers or less in diameter. (PM2.5) is generally described as fine particles
PM10 and PM2.5 particles make up a large proportion of dust that can be drawn deep into the lungs. Some particles are large or dark enough to be seen as soot or smoke. Others are so small they can be detected only with an electron microscope. Larger particles tend to be trapped in the nose, mouth or throat.
Because particles originate from a variety of mobile and stationary sources (diesel trucks, cars, woodstoves, power plants, lawn mowers, leaf blowers, volcanoes, etc.), their chemical and physical compositions vary widely.
PM10 and PM2.5 particles make up a large proportion of dust that can be drawn deep into the lungs. Some particles are large or dark enough to be seen as soot or smoke. Others are so small they can be detected only with an electron microscope. Larger particles tend to be trapped in the nose, mouth or throat.
Because particles originate from a variety of mobile and stationary sources (diesel trucks, cars, woodstoves, power plants, lawn mowers, leaf blowers, volcanoes, etc.), their chemical and physical compositions vary widely.
PM can alter the body's defense systems against foreign materials, damage lung tissues, aggravate existing respiratory and cardiovascular disease, and can lead to cancer. In some cases, PM exposure can even lead to premature death. Adverse health effects have been associated with exposures to PM over both short periods (such as a day) and longer periods (a year or more).
The people who are most at risk are people with asthma, influenza, lung, heart, or cardiovascular disease, the elderly, and children.
The people who are most at risk are people with asthma, influenza, lung, heart, or cardiovascular disease, the elderly, and children.
