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Particulate Matter (PM)

Fast Facts

  • Particles that are less than 2.5 micrometers in diameter are known as "fine" particles; those larger than 2.5 micrometers, but less than 10 micrometers, are known as "coarse" particles.
  • Fine particles are easily inhaled deep into the lungs where they may accumulate, react, be cleared or absorbed.
  • Scientific studies have linked particle pollution, especially fine particles, with a series of significant health problems, including:
    • premature death in people with heart or lung disease,
    • nonfatal heart attacks,
    • irregular heartbeat,
    • aggravated asthma,
    • decreased lung function, and
    • increased respiratory symptoms, such as irritation of the airways, coughing or difficulty breathing.
  • Particle pollution can cause coughing, wheezing, and decreased lung function even in otherwise healthy children and adults.
  • Studies estimate that thousands of elderly people die prematurely each year from exposure to fine particles.
  • The average adult breathes 3,000 gallons of air per day.
  • According to the American Academy of Pediatrics, children and infants are among the most susceptible to many air pollutants. Children have increased exposure compared with adults because of higher minute ventilation and higher levels of physical activity.
  • Fine particles can remain suspended in the air and travel long distances. For example, a puff of exhaust from a diesel truck in Los Angeles can end up over the Grand Canyon.
  • Some of the pollutants which form haze have also been linked to serious health problems and environmental damage.
  • Particle pollution settles on soil and water and harms the environment by changing the nutrient and chemical balance.
  • Particle pollution, unlike ozone, can occur year-round.
  • People can reduce their exposure to air pollution by checking their daily air quality forecast and adjusting strenuous outdoor activities when an unhealthy AQI is forecast.


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