Ambient Air Monitoring Program

Condensed from Health and Environmental Effects Of Particulate Matter; Office of Air Quality Planning and Standards, US EPA; July 1997.

Sources

Particulate matter originates from a variety of sources, including diesel trucks, power plants, wood stoves and industrial processes. The chemical and physical composition of these various particles vary widely. While individual particles cannot be seen with the naked eye, collectively they can appear as black soot, dust clouds, or grey hazes.

Those particles that are less than 2.5 micrometers in diameter are known as “fine” particles; those larger than 2.5 micrometers are known as “coarse” particles. Fine particles result from fuel combustion (from motor vehicles, power generation, industrial facilities), residential fireplaces and wood stoves. Fine particles can be formed in the atmosphere from gases such as sulfur dioxide, nitrogen oxides, and volatile organic compounds. Coarse particles are generally emitted from sources such as vehicles traveling on unpaved roads, materials handling, and crushing and grinding operations, and windblown dust.

EPA is also maintaining a national air quality standard focused on small particles less than 10 micrometers in diameter (known as “PM10”) to protect against coarse particle effects. Ten micrometers are about one-seventh the diameter of a human hair.

Health Effects

Particulates are of health concern because they easily reach the deepest recesses of the lungs.

Scientific studies have linked particulate matter, especially fine particles (alone or in combination with other air pollutants), with a series of significant health problems, including:

• Premature death
• Respiratory related hospital admissions and emergency room visits
• Aggravated asthma
• Acute respiratory symptoms, including aggravated coughing and difficult or painful breathing
• Chronic bronchitis
• Decreased lung function that can be experienced as shortness of breath
• Work and school absences

Who is Most at Risk from Exposure to Fine Particles?

• The Elderly

  Studies estimate that tens of thousands of elderly people die prematurely each year from exposure to ambient levels of fine particles. Studies also indicate that exposure to fine particles is associated with thousands of hospital admissions each year. Many of these hospital admissions are elderly people suffering from lung or heart disease.

• Individuals with Preexisting Heart or Lung Disease:

  Breathing fine particles can also adversely affect individuals with heart disease, emphysema, and chronic bronchitis by causing additional medical treatment. Inhaling fine particulate matter has been attributed to increased hospital admissions, emergency room visits and premature death among sensitive populations.

• Children

  The average adult breathes 13,000 liters of air per day; children breathe 50 percent more air per pound of body weight than adults. Because children’s respiratory systems are still developing, they are more susceptible to environmental threats than healthy adults. Exposure to fine particles is associated with increased frequency of childhood illnesses, which are of concern both in the short run, and for the future development of healthy lungs in the affected children. Fine particles are also associated with increased respiratory symptoms and reduced lung function in children, including symptoms such as aggravated coughing and difficulty or pain in breathing. These can result in school absences and limitations in normal childhood activities.

  More and more people are being diagnosed with asthma every year. Fourteen Americans die every day from asthma, a rate three times greater than just 20 years ago. Children make up 25 percent of the population, but comprise 40 percent of all asthma cases. Breathing fine particles, alone or in combination with other pollutants, can aggravate asthma, causing greater use of medication and resulting in more medical treatment and hospital visits.

Man-made Materials

Fine particles can also soil man-made materials, speed their deterioration, and impair visibility.

Air Quality Levels PM 2.5

The ambient air quality standard for PM2.5, which is designed to protect public health with an adequate margin of safety, is 35 µg/m3 averaged over a 24-hour period and 12 µg/m3 annual average. For more details, see http://www.epa.gov/air/criteria.html