What You Need to Know About Ozone and Your Health. In fact, breathing smoggy air can be hazardous because smog contains ozone, a pollutant that can harm our health when there are elevated levels in the air we breathe. This publication will tell you what kinds of health effects ozone can cause, when you should be concerned, and what you can do to avoid dangerous exposures.
On a hot, smoggy summer day, have you ever wondered: Is the air safe to breathe? Should I be concerned about going outside? Ozone is a colorless gas composed of three atoms of oxygen.
Ozone occurs naturally in the Earth's upper atmosphere-10 to 30 miles above the Earth's surface-where it forms a protective layer that shields us from the sun's harmful ultraviolet rays.
In the Earth's lower atmosphere, near ground level, ozone is formed when pollutants emitted by cars, power
plants, industrial boilers, refineries, chemical plants, and other sources react chemically in the presence of sunlight.
Should I be concerned about exposure to ground-level ozone? That depends on who you are and how much ozone is in the air. Most people only have to worry about ozone exposure when ground-level concentrations reach high levels. In many U.S. communities, this can happen frequently during the summer months. In general, as ground-level ozone concentrations increase, more and more people experience health effects, the effects become more
serious, and more people are admitted to the hospital everyone should be concerned about ozone exposure.
Children and adults of all ages who are active outdoors are at risk from ozone exposure. Scientists have found that about one out of every three people in the United States is at a higher risk of experiencing ozone-related health effects If you are a member of a "sensitive group," you should pay special attention to ozone levels in your area. This publication describes several tools that the U.S. Environmental Protection Agency (EPA), in partnership with State and local agencies, has developed to inform the public about local ozone levels. These tools provide the information you need to decide whether ozone levels on any particular day may be harmful to you. When ozone concentrations reach unhealthy levels, you can take simple precautions (described in "What can I do to avoid unhealthy exposure to ozone?") to protect your health.
Ozone can inflame the lung's lining, and repeated episodes of inflammation may cause permanent changes in the
How might ozone affect my health?
Scientists have been studying the effects of ozone on human health for many years. So far, they have found that ozone can cause several types of short-term health effects in the lungs:
Ozone can irritate the respiratory system.
When this happens, you might start coughing, feel an irritation in your throat, and/or experience an uncomfortable sensation in your chest. These symptoms can last for a few hours after ozone exposure and may even become painful.
Ozone can reduce lung function.
When scientists refer to "lung function," they mean the volume of air that you draw in when you take a full breath and the speed at which you are able to blow it out. Ozone can make it more difficult for you to breathe as deeply and vigorously as you normally would. When this happens, you may notice that breathing starts to feel uncomfortable. If you are exercising or working outdoors you may notice that you are taking more rapid and shallow breaths than normal. Reduced lung function can be a particular problem for outdoor workers, competitive athletes, and other people who exercise outdoors.
Ozone can aggravate asthma.
When ozone levels are high, more asthmatics have asthma attacks that require a doctor's attention or the use of additional medication. One reason this happens is that ozone makes people more sensitive to allergens, which are the most common triggers for asthma attacks. (Allergens come from dust mites, cockroaches, pets, fungus, and
pollen.) Also, asthmatics are more severely affected by the reduced lung function and irritation that ozone causes in the respiratory system.
Most of these effects are considered to be short-term effects because they eventually cease once the individual is no longer exposed to elevated levels of ozone. However, scientists are concerned that repeated short-term damage from ozone exposure may permanently injure the lung. For example, repeated ozone impacts on the developing lungs of children may lead to reduced lung function as adults. Also, ozone exposure may speed up the decline in lung function that occurs as a natural result of the aging process. Research is underway to help us better understand the possible long-term effects of ozone exposure.