Air Quality Index
|Green||Good - No health impacts expected within this range.|
|Yellow||Moderate - Unusually sensitive people should consider limiting prolonged outdoor exertion.|
|Orange||Unhealthy for Sensitive Groups - Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.|
|Red||Unhealthy - Active children and adults, and people with respiratory disease, such as asthma, should avoid prolonged outdoor exertion. Everyone else, especially children, should limit prolonged outdoor exertion.|
|Purple||Very Unhealthy - Active children and adults, and people with respiratory disease, such as asthma, should avoid all prolonged outdoor exertion. Everyone else, especially children, should limit prolonged outdoor exertion.|
The Environmental Protection Agency (EPA) has developed the Air Quality Index, or AQI, for reporting the levels of ozone and other common air pollutants. The index makes it easier for the public to understand the health significance of air pollution levels. Although physical exertion helps build up strength in the heart and lungs, exerting yourself outdoors can actually increase your chances of experiencing health effects when ozone concentrations are at unhealthy levels. Exertion generally causes you to breathe harder and faster. When this happens, more ozone is taken into your lungs and ozone reaches tissues that are susceptible to injury.
Who is at Risk?
Roughly one out of every three people in the United States is at a higher risk of experiencing ozone-related health effects. Sensitive people include children and adults who are active outdoors, people with respiratory disease, such as asthma, and people with unusual sensitivity to ozone.
One group at high risk from ozone exposure is active children because this group often spends a large part of the summer playing outdoors. However, people of all ages who are active outdoors are at increased risk because, during physical activity, ozone penetrates deeper into the parts of the lungs that are more vulnerable to injury.
People with respiratory diseases that make their lungs more vulnerable to ozone may experience health effects earlier and at lower ozone levels than less sensitive individuals.
Ozone can irritate the respiratory system, causing coughing, throat irritation and/or an uncomfortable sensation in the chest.
Ozone can reduce lung function and make it more difficult to breathe deeply and vigorously. Breathing may become more rapid and shallow than normal. This reduction in lung function may limit a person’s ability to engage in vigorous outdoor activities.
Ozone can aggravate asthma. When ozone levels are high more people with asthma have attacks that require a doctor’s attention or the use of additional medication.
Ozone can increase susceptibility to respiratory infections.
Ozone can inflame and damage the lining of the lungs. What are the health risks and who is most at risk?
What is Ozone?
Ozone is an odorless, colorless gas composed of three atoms of oxygen. Ozone occurs both in the Earth's upper atmosphere and at ground level. Ozone can be good or bad, depending on where it is found.
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. This beneficial ozone is gradually being destroyed by manmade chemicals. An area where ozone has been significantly depleted — for example, over the North or South Pole — is sometimes called a "hole in the ozone."
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. Ozone at ground level is a harmful pollutant. Ozone pollution is a concern during the summer months, when the weather conditions needed to form it — lots of sun, hot temperatures — normally occur.
What Can You Do?
Since 48% of the precursors to ozone pollution in the Metroplex is caused by emissions from vehicles such as cars and trucks, the most important thing any North Texan can do to improve air quality in North Texas is to drive less.
Share A Ride
For information about carpool, vanpool and mass transit options:
- In the Dallas area contact DART at:214-747-RIDE or www.dart.org
- In the Fort Worth area contact The T at:817-336-RIDE or www.the-t.com
Keep Your Vehicle Well-Maintained
You might be surprised to learn that the emissions from one poorly maintained vehicle can equal those from 25 properly functioning vehicles!
Report Smoking Vehicles
You can help the Texas Natural Resource Conservation Commission get the word out to owners of smoking vehicles. The next time you see a car, truck or bus with dirty smoke coming from its exhaust for more than 10 consecutive seconds, get the license number and call 1-800-453-SMOG.
Pay Attention to Air Pollution Watch Days
High levels of air pollution occur in this region throughout the summer months, so it is important to practice ozone reducing behaviors every day during that season.
Combine Trips to Minimize Cold Starts
Most vehicle emissions occur when the engine and catalytic converter are cold.
Drive at fuel-saving, moderate speeds
Jack-rabbit acceleration uses more fuel than your engine can efficiently run.
Avoid excessive idling
Drive during offpeak hours to avoid congested traffic. Avoid highway construction projects and lines at drive-through windows.
Refuel your vehicle carefully and in the evening when it’s cooler
Avoid spilling gasoline, don’t top off the tank and check to make sure your gas cap seals properly.
Don’t mow your lawn or use gaspowered lawn equipment in the morning on Air Pollution Watch days
One hour of lawn care machine operation equals 50 miles of car driving.
Buy environmentally friendly cleaners
Avoid using aerosol products and select water-based paintSource: U.S. Environmental Protection Agency