Air Contaminants
Ozone
Ozone is a gas that you cannot see or smell. Ozone occurs naturally in the sky about 10 to 30 miles above the earth's surface. Sometimes, this ozone is called "good ozone" because it forms a layer that protects life on earth from the sun's harmful rays.
Ground-level ozone, on the other hand, can be bad for your health and the environment. Ground-level ozone forms when pollutants from cars and trucks, power plants, factories, and other sources come in contact with each other in heat and sunlight. Factors such as weather conditions and intensity of sunlight also play a part in how ozone is formed. Ground-level ozone is one of the biggest parts of smog, and it is usually worse in the summer months.
Many urban areas tend to have higher levels of ground-level ozone. However, rural areas have ground-level ozone, too. Wind carries ozone and the pollutants that form it hundreds of miles from their original sources, and rural areas have sources of ozone that contribute to this problem.
Ozone and Health
When ozone levels are very high, everyone should be concerned about ozone exposure. But ozone bothers some people more than others, mainly when they are outside. People in these groups may feel the effects of ozone when they are outside for short periods of time, even if they are only doing light activities. Those most likely to be bothered by ozone include
- people with asthma or lung disease because they will feel the effects of ozone sooner and at lower ozone levels than less-sensitive people.
- children who spend a lot of time outdoors. Children are also more likely than adults to have asthma, which may be aggravated when they breathe in ozone. Being exposed to ozone for short periods of time over many years may cause children to have more breathing problems as adults.
- older adults because they are more likely to have heart or lung disease.
- active people of all ages who exercise or work hard outside because they are in contact with ozone more than people who spend more time indoors.
- infants because their lungs continue to develop after birth and can be impacted by air pollutants.
Many scientific studies have linked ground-level ozone contact to such varied problems as
- aggravation of asthma, bronchitis, and emphysema
- coughing and pain when taking a deep breath;
- higher chance of getting respiratory illness such as pneumonia or bronchitis;
- lung and throat irritation; and
- wheezing and breathing difficulties during exercise or outdoor activities.
As a result of these studies, scientists know that breathing in too much ozone can increase events such as
- use of asthma medication,
- absences from school,
- visits to the emergency room and hospital admissions, and
- premature death from heart and lung disease.
Protect yourself and your family
EPA's Air Quality Index, or AQI, is a tool to help you quickly learn when air pollution is likely to reach unhealthy levels. Local TV stations, radio programs, and newspapers carry these air quality forecasts to tell you when particle levels are likely to be unhealthy. You can use the AQI to plan your daily activities to reduce exposure to ozone.
Your exposure to ozone depends mainly on where you live and work and how much time you spend outside. When ozone levels are high, you can
- reduce the amount of time you spend outside;
- plan outdoor activities when ozone levels are lower, usually in the morning and evening;
- do easier outdoor activities, such as walking instead of running; and
- plan indoor activities.
Particulate Matter
Particle pollution, or particulate matter, consists of particles that are in the air, including dust, dirt, soot and smoke, and little drops of liquid. Some particles, such as soot or smoke, are large or dark enough to be seen. Other particles are so small that you cannot see them.
Particle pollution can come from primary or secondary sources. A primary source, such as wood stoves or forest fires, lets off particle pollution directly. A secondary source lets off gases that react and form particles. Examples of secondary sources are coal fires and power plants. Particle pollution also comes from motor vehicles, factories, and construction sites. These can be primary or secondary sources. Particle pollution can be a problem at different times of the year, depending on where you live.
Particle pollution includes
- coarse particles that are between 2.5 and 10 micrometers,
- fine particles that are between 0.1 micrometers and 2.5 micrometers; also known as PM2.5, and
- ultrafine particles that are smaller than 0.1 micrometers.
Particles bigger than 10 micrometers can irritate your eyes, nose, and throat but do not usually reach your lungs. Ten micrometers is about seven times thinner than one human hair.
Fine and ultrafine particles are the most concerning because they are most likely to cause health problems. Their small size allows them to get into the deep part of your lungs and even into your blood.
Particulate Matter and Health
Being exposed to any kind of particulate matter may cause
- increased emergency department visits and hospital stays for breathing and heart problems,
- worsened asthma symptoms,
- adverse birth outcomes,
- breathing problems,
- decreased lung growth in children,
- lung cancer, and
- early deaths.
People who are at the highest risk of being bothered by particulate matter include
- people with heart or lung diseases because they will feel the effects of particulate matter sooner and at lower ozone levels than less-sensitive people.
- older adults because they may not know they have lung or heart disease. When particle levels are high, older adults are more likely than young adults to have to go to the hospital or die because the exposure to particle pollution has made their heart or lung disease worse.
- children because they are still growing and spend more time at high activity levels. When children come in contact with particle pollution over a long period of time they may have problems as their lungs and airways are developing. This exposure may put them at risk for lowered lung function and other respiratory problems later in life. Children are more likely than adults to have asthma and other respiratory problems that can worsen when particle pollution is high.
- infants because their lungs continue to develop after birth and can be impacted by air pollutants.
Protect yourself and your family
EPA's Air Quality Index, or AQI, is a tool to help you quickly learn when air pollution is likely to reach unhealthy levels. Local TV stations, radio programs, and newspapers carry these air quality forecasts to tell you when particle levels are likely to be unhealthy. You can use the AQI to plan your daily activities to reduce exposure to particle pollution.
When particle pollution levels are high, you can
- reduce the amount of time you spend outside;
- do easier outdoor activities, such as walking instead of running or using a riding lawn mower instead of a push mower; and
- exercise away from roads and highways. Particle pollution is usually worse near these areas.
If you have one of the following diseases, you may experience some effects from particle pollution:
Lung disease
- You may not be able to breathe as deeply or strongly as you usually do.
- You may cough more, have chest pain, wheeze, feel like you can't catch your breath, or be tired more than usual.
Heart disease
- Coming in contact with particle pollution can cause serious problems in a short period of time, such as a heart attack without any warning signs.
- Symptoms, including chest pain or tightness, fast heartbeat, feeling out of breath, and feeling tired more than usual, may be signs of a serious problem. If you have any of these signs, follow your doctor's advice and contact your doctor if the symptoms last longer than usual or worsen.
Asthma
- Follow your asthma management plan when particle levels are high.
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