Air Pollution & Air Quality

Particle Pollution Air Quality Guide

August 22, 2011, 6:46 am
Source: U.S. Environmental Protection Agency
Content Cover Image

Particulate pollution enhancing Mumbai sunset. Source: Wikimedia Commons.

Particles in the air can cause or aggravate a number of health problems and have been linked with illnesses and deaths from heart or lung diseases.

Air Quality Guide for Particle Pollution


AQI color code

Who is affected?

What is the significance?

What action should people take?



Air quality is good

Enjoy activities


People who are unusually sensitive to air pollution

Air quality is a concern for people who are unusually sensitive to air pollution

People unusually sensitive to air pollution: Plan strenuous activities when air quality is better


People with heart or lung disease (including asthma), older adults, and children

Air quality is unhealthy for people in sensitive groups

Sensitive groups: Cut back or reschedule strenuous activities


Everyone, especially people with heart or lung disease (including asthma), older adults, and children

Air quality is unhealthy for everyone

Everyone: Cut back or reschedule strenuous activities

Sensitive groups: Avoid strenuous activities


Everyone, especially people with heart or lung disease (including asthma), older adults, and children

Air quality is very unhealthy for everyone

Everyone: Significantly cut back on physical activities

Sensitive groups: Avoid all physical activities


Key Facts You Should Know About Particle Pollution

Particles in the air can cause or aggravate a number of health problems and have been linked with illnesses and deaths from heart or lung diseases.

At highest risk from particle pollution are people with heart or lung disease, older adults (possibly because they may have undiagnosed heart or lung disease), and children whose lungs are still developing and who are more likely to have asthma and are more active outdoors.

Particles of concern include both very small, "fine" particles (that can only be seen through an electron microscope) and somewhat larger "coarse" dust particles. Fine particles have been more clearly linked to the most serious health problems.

What are particles? Where do they come from?

Particles in the air are a mixture of solids and liquid droplets that vary in size and are often referred to as "particulate matter." Some particles - those less than 10 micrometers in diameter - pose the greatest health concern because they can pass through the nose and throat and get deep into the lungs. Ten micrometers in diameter is just a fraction of the diameter of a single human hair. Particles larger than 10 micrometers do not usually reach your lungs, but they can irritate your eyes, nose and throat.

Very small particles with diameters less than 2.5 micrometers are called "fine particles." They are produced any time fuels such as coal, oil, diesel or wood are burned. Fine particles come from fuel used in everything from power plants to wood stoves and motor vehicles (e.g., cars, trucks, buses and marine engines). These particles are even produced by construction equipment, agricultural burning and forest fires.

"Coarse" dust particles range in size from 2.5 to 10 micrometers in diameter. Particles of this size are produced during crushing or grinding and from vehicles traveling on paved or unpaved roads.

How can particle pollution affect you?

Fine and coarse particles can cause a variety of serious health problems. When exposed to these particles, people with heart or lung diseases and older adults are more at risk of hospital and emergency room visits or, in some cases, even death. These effects have been associated with short-term exposures lasting 24 hours or less. Long-term exposures of a year or more have been linked to the development of lung diseases, such as chronic bronchitis.

Particles can aggravate heart diseases such as congestive heart failure and coronary artery disease. If you have heart disease, particles may cause you to experience chest pain, palpitations, shortness of breath and fatigue. Particles have also been associated with cardiac arrhythmias and heart attacks.

Particles can aggravate lung diseases such as asthma and bronchitis, causing increased medication use and doctor visits. If you have lung disease, and you are exposed to particles, you may not be able to breathe as deeply or vigorously as normal. You may have respiratory symptoms including coughing, phlegm, chest discomfort, wheezing and shortness of breath. You also may experience these symptoms even if you're healthy, although you are unlikely to experience more serious effects. Particles can also increase your susceptibility to respiratory infections.

How can you reduce your exposure to particles?

Air pollution levels can vary throughout the day. Your local air quality forecast can tell you when particle levels are high in your area. You can reduce your exposure to particles by 1) planning strenuous activity when particle levels are forecast to be lower, 2) reducing the amount of time spent at vigorous activity, or 3) choosing a less strenuous activity (e.g., going for a walk instead of a jog).

When particle levels are high outdoors, they also can be high indoors. Certain filters and room air cleaners are available that can help reduce particles indoors. You also can reduce particles indoors by eliminating tobacco smoke and reducing your use of candles, wood-burning stoves and fireplaces. For more information on indoor air pollution and filter devices, visit

For your local forecast visit this Encyclopedia of Earth article on AIRNow.

  • You Can Help Keep the Air Cleaner!
  • Every day tips:
  • Conserve electricity.
  • Consider setting your thermostat a little higher in the summer and lower in winter.
  • Participate in local energy conservation programs.
  • Look for the ENERGY STAR label when buying home or office equipment.
  • Keep car, boat and other engines properly tuned, and avoid engines that smoke.
  • Car pool, use public transportation, bike or walk when possible.
  • Combine errands to reduce "cold starts" of your car and avoid extended idling.
  • Consider using gas logs instead of wood. If you use a wood-burning stove or fireplace insert, make sure it meets EPA design specifications. Burn only dry, seasoned wood.
  • Mulch or compost leaves and yard waste.
  • Tips for days when particle pollution is expected to be high:
  • Reduce the number of trips you take in your car.
  • Reduce or eliminate fireplace and wood stove use.
  • Avoid using gas-powered lawn and garden equipment.
  • Avoid burning leaves, trash and other materials.



Office of Air and Radiation (6301A)
EPA 452/F-03-002
August 2003



(2011). Particle Pollution Air Quality Guide. Retrieved from


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