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Particulate Matter Effects on Health

Photo of a hiker on trail to Bear Paw High Sierra Camp, Sequoia and Kings Canyon National Park, California
Hiker on trail to Bear Paw High Sierra Camp, Sequoia and Kings Canyon National Park, California.

Very small (fine) particulate matter concentrations approach or exceed the National Ambient Air Quality Standard in several National Park Service (NPS) areas. The NPS therefore issues fine particulate health advisories at several areas.

What is particulate matter?

Particle pollution is made up of a mixture of microscopic solids and liquid droplets suspended in air. This pollution, also known as particulate matter, includes acids (such as nitrates and sulfates), organic chemicals, metals, soil or dust particles, and allergens (such as fragments of pollen or mold spores).

Particle size is directly linked to the potential for causing health problems. Particles smaller than 10 micrometers in diameter pose the greatest problems because they can get deep into your lungs and some may even get into your bloodstream. Larger particles are can irritate your eyes, nose, and throat, but are of less concern for health impacts.

Particles of concern are classified as “fine particles” (found in smoke and haze), which are 2.5 micrometers in diameter or less, and “coarse particles” (found in wind-blown dust), which have diameters between 2.5 and 10 micrometers.

How can particulate matter affect your health?

Particle exposure can lead to a variety of health effects. Both long- and short-term particle exposures have been linked to health problems. Long-term exposures, such as those experienced by people living for many years in areas with high particle levels, have been associated with problems such as reduced lung function and the development of chronic bronchitis and even premature death. Short-term exposures to particles (hours or days) can aggravate lung disease, causing asthma attacks and acute bronchitis, and may also increase susceptibility to respiratory infections. In people with heart disease, short-term exposures have been linked to heart attacks.

Healthy children and adults have not been reported to suffer serious effects from short-term exposures, although they may experience temporary minor irritation when particle levels are elevated.


What are the symptoms of particle exposure?

Even if you are healthy, you may experience temporary symptoms, such as irritation of the eyes, nose, and throat, coughing, phlegm, chest tightness, and shortness of breath when particulate conditions are poor. If you have lung disease, you may not be able to breathe as deeply or as vigorously as normal, and you may experience coughing, chest discomfort, wheezing, shortness of breath, and unusual fatigue during periods of elevated particulate matter pollution.


Who is at risk?

People with heart or lung disease, diabetics, older adults, and children are considered at greater risk from particulate matter pollution than other people, especially when they are physically active. Exercise and physical activity cause people to breathe faster and more deeply drawing more particles into their lungs.

People particularly sensitive to particulate matter include:

  • People with heart or lung diseases such as coronary artery disease, congestive heart failure, and asthma or chronic obstructive pulmonary disease (COPD) are at increased risk, because particles can aggravate these diseases.
  • People with diabetes also may be at increased risk, possibly because they are more likely to have underlying cardiovascular disease.
  • Older adults are at increased risk, possibly because they may have undiagnosed heart or lung disease or diabetes.
  • Children are likely at increased risk for several reasons. Their lungs are still developing; they spend more time at high activity levels; and they are more likely to have asthma or acute respiratory diseases, which can be aggravated when particle levels are high.


How can I avoid unhealthy exposure?

When particulate pollution occurs, your chances of being affected increase with strenuous activity and the length of time you are active outdoors. If your planned activity involves prolonged or heavy exertion and the particulate levels are high, you may want to limit or discontinue your activity.


What are National Park Service PM2.5 health advisories?

Air quality in some parks may at times exceed the National Ambient Air Quality Standard for fine particulate matter (PM2.5), those particles less than or equal to 2.5 micrometers (µm). Elevated levels of PM2.5 in National Park Service areas may come from smoke associated with forest fires in and adjacent to the parks.

The PM2.5 public health standard is based on a 24-hour and annual concentration. The 24-hour standard is used as a basis for health advisories in the parks. The 24-hour standard is set at 35 micrograms per cubic meter parts (µg/m3). Using the EPA air quality index, the NPS PM2.5 health advisories are based on the levels shown below.

Air Quality Index (ppb) diagram for particulate matter

PM2.5 health advisories for National Park Service areas can be viewed at


How does particulate matter affect national parks?

Particulate matter pollution can also reduce visibility in the national parks. Particles in the air can travel hundreds and thousands of miles, contributing to the haze that causes reduced visibility in national parks and broad areas of the United States. Learn more »


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Last Updated: January 03, 2017