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Air Quality and Your Health

In the Washington, DC metropolitan area, the two most important pollutants that threaten human health are ground-level ozone and particle pollution. If you are a typical adult, you'll breathe in close to 3,500 gallons of air in a single day. If your atmosphere is polluted with ozone and particle pollution, you may see your lung function reduced by as much as 20 percent.

Ground-Level Ozone

Particle Pollution

Ground-Level Ozone
Ozone is an extremely reactive gas comprised of three atoms of oxygen. Ozone exists naturally in the earth's upper atmosphere, the stratosphere, where it shields the earth from the sun's harmful ultraviolet rays. However, ozone found close to the earth's surface, called ground-level ozone, is a component of smog and a harmful pollutant.

What is ground-level ozone? Where does it come from?

Ground-level ozone is a colorless gas that can be found in the air we breathe. It is formed through a complex chemical reaction between volatile organic compounds (VOCs) and nitrogen oxides (NOx) in the presence of sunlight. Sources of manmade VOCs and NOx include: 1) automobiles, trucks and buses; 2) gasoline storage and transfer; 3) large combustion and industry sources such as utilities; 4) industrial use of solvents and degreasing agents; 5) consumer products such as paints and cleaners; and 6) off-road engines such as aircraft, locomotives, boats, construction equipment and lawn and garden equipment. VOC's are also produced naturally by certain types of vegetation.

Who is considered most at risk from exposure to ground-level ozone?

• Children are the most at risk from exposure to ground-level ozone: their respiratory systems are still developing and they breathe more air per pound of body weight than adults. Ground-level ozone is a summer time problem; children spend most of the summer outside playing at summer camps, playgrounds, neighborhood parks and in backyards.
  
• Individuals suffering with a respiratory disease are also at risk because exposure to ground-level ozone inhibits the lungs' ability to function properly. People with existing lung disease (e.g., asthma, chronic bronchitis, emphysema) already suffer from reduced lung function and, therefore, cannot tolerate an additional reduction due to ozone exposure.
  
• Healthy adults, as confirmed by many laboratory and "real world" ozone exposure studies are also at risk. People who exercise or otherwise participate in activities that increase their respiratory rate, respond much more severely to ground-level ozone exposure than people at rest. This means that adults exercising outdoors, construction workers and other outdoor workers are at risk during the summer months.

Particle Pollution
Particulate matter is a pollutant that includes both solid particles and liquid droplets found in air. Particulate matter is associated with serious health affects including increased hospital and emergency room visits for people with respiratory and heart disease. Particulate matter also effects the natural environment in which we live. It is the major source of haze that reduces visibility in many parts of the United States. When deposited on soil and water, it can harm the environment by changing the nutrient and chemical balance.

What is particulate matter? Where does it come from?

"Particulate matter" is the term for particles found in the air, including dust, dirt, soot, smoke, and liquid droplets. These particles come in a wide range of sizes. Particles less than 10 micrometers in diameter tend to pose the greatest health concern because they can be inhaled and accumulate in the respiratory system. Particles less than 2.5 micrometers in diameter are termed "fine" particles. Some particles are directly emitted into the air. They come from a variety of sources such as cars, trucks, buses, factories, construction sites, tilled fields, unpaved roads, stone crushing, and burning of wood. Other particles may be formed in the air from the chemical change of gases. They are indirectly formed when gases from burning fuels react with sunlight and water vapor. These can result from fuel combustion in motor vehicles, at power plants, and in other industrial processes.

What are the health effects and who is most at risk from exposure to particulate matter?

• When exposed to particulate matter, people with existing heart or lung diseases-such as asthma, chronic obstructive pulmonary disease, congestive heart disease, or ischemic heart disease-are at increased risk of premature death or admission to hospitals or emergency rooms.
  
• The elderly also are sensitive to particulate matter exposure. They are at increased risk of admission to hospitals or emergency rooms and premature death from heart or lung diseases.
  
• When exposed to particulate matter, children and people with existing lung disease may not be able to breathe as deeply or vigorously as they normally would, and they may experience symptoms such as coughing and shortness of breath.
  
• Particulate matter can increase susceptibility to respiratory infections and can aggravate existing respiratory diseases, such as asthma and chronic bronchitis, causing more use of medication and more doctor visits.

How can I get additional information?

Contact the Metropolitan Washington Council of Governments Air Quality Hotline:
202-962-3299

Visit the following web sites:

• Clean Air Partners - the Baltimore/Washington air quality public education and outreach program with real-time air quality data.
• National Air Quality information can be found on the EPA Airnow web site.
• Page on the Air Quality Index can be found at http://cfpub.epa.gov/airnow/index.cfm?action=static.aqi.
• EPA publications on Air Quality can be found at http://www.epa.gov/oar/oarpubs.html.
• Information about Air Quality can be found at http://www.epa.gov/oar/oaqps/cleanair.html.