|Particulate Matter||en español|
Particulate matter is the dust and soot found in the air.
What is particulate matter?
Particulate matter is the term for tiny particles found in the air. These particles can include dust, dirt, soot, smoke, and liquid droplets. Some particulate matter is large and dark enough to be seen, such as soot and smoke. Other particulate matter is so fine that it can be detected only with a microscope that examines air.
Particulate matter is sometimes abbreviated "PM". The Environmental Protection Agency is concerned with two sizes of particles: PM-10 and PM-2.5. PM-10 describes coarse particles with a diameter of 10 micrometers or less (0.0004 inches or one-seventh the width of a human hair). Fine particles, those smaller than 2.5 micrometers in diameter, are designated PM-2.5.
Particulate matter can be found in pollution emitted into the air. Particulate matter is in emissions from cars, trucks, buses, factories, construction sites, tilled fields, unpaved roads, stone crushing, and burning wood.
Particulate matter is formed indirectly when emissions from burning fuels -- especially emissions from motor vehicles, electric power plants, and other industrial processes -- react with sunlight and water vapor. These fuels include crude oil, diesel, and gasoline. It is also formed by grilling food on charcoal or gas, burning leaves and brush, and burning wood in a fireplace or wood stove.
Particulate matter is a common air pollutant found in most of the air in the United States. You can be exposed to particulate matter outdoors by breathing polluted air that contains it. Particulate matter levels can vary according to the weather, time of year, and location. You are most likely to be exposed to particulate matter in the summer, when the sun and hot temperatures react with pollution to form smog, causing government officials to issue air quality alerts.
You can be exposed to high levels of particulate matter if you live near an industrial site that emits particulate matter or if you exercise near high-traffic areas. You can also be exposed at home or at work, indoors or outdoors, through smoking cigarettes or breathing second-hand smoke.
High concentrations of particulate matter, especially the fine particles of particulate matter, have been found to present a serious threat to human health if they accumulate in the respiratory system. The way particulate matter can affect your health depends on the size of the particles and the level of their concentration in the air. The fine particles of particulate matter can be inhaled deeply into the lungs, where they remain embedded for long periods of time, or can be absorbed into the bloodstream. Prolonged exposure to fine particulate matter can cause increased respiratory disease, decreased lung function, chronic bronchitis, and even premature death due to respiratory problems.
Deisel exhaust particulates are listed as "reasonably anticipated to be a human carcinogen" in the Fourteenth Report on Carcinogens published by the National Toxicology Program because occupational exposure to diesel exhaust particles has been associated with elevated lung cancer rates.
Short-term exposure to large particles of particulate matter can aggravate respiratory conditions such as asthma. It can also cause increased coughing, wheezing, respiratory irritation, and painful breathing.
Particulate matter is especially harmful to people with lung diseases such as asthma, chronic bronchitis, chronic obstructive pulmonary disease, and emphysema. Other people who are sensitive to particulate matter exposure are children, the elderly, and people with heart disease.
For poisoning emergencies or questions about possible poisons, please contact your local poison control center at 1-800-222-1222.
This description is based on the information found in the Web links listed with this topic.
Web Links from MedlinePlus (National Library of Medicine)
Indoor Air Pollution
Aerosols (National Institute for Occupational Safety and Health)
Air Quality Designations for Particle Pollution (Environmental Protection Agency)
Particulate Matter (PM 2.5) Trends (Environmental Protection Agency)
Particulate Matter (PM) Pollution (Environmental Protection Agency)
Particulate Matter (PM10) Trends (Environmental Protection Agency)
Visibility: Basic Information (Environmental Protection Agency)
Last Updated: April 20, 2017