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Ground Level Ozone

Ground Level Ozone
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Basic Information Designations Implementation Air Quality Standards

Health Effects Ecosystem Effects Reduction Strategies National Programs to Reduce Ozone NAAQS Table

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What is Ozone?

Ozone Good Up High Bad Nearby Ground level or "bad" ozone is not emitted directly into the air, but is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC) in the presence of sunlight. Emissions from industrial facilities and electric utilities, motor vehicle exhaust, gasoline vapors, and chemical solvents are some of the major sources of NOx and VOC. Learn more about ozone.

Ozone and Your Health

image of lungs and airwaysAbout 25 million people, including 7 million children, have asthma and over 12 million people report having an asthma attack in the past year. Breathing ozone can trigger a variety of health problems including chest pain, coughing, and throat irritation. It can worsen bronchitis, emphysema, and asthma. Ground level ozone also can reduce lung function and inflame the linings of the lungs. Repeated exposure may permanently scar lung tissue. Learn more about the health effects of ozone

Ozone and Ecosystems

image of tree and root systemGround level ozone can have harmful effects on sensitive vegetation and ecosystems. Plant species that are sensitive to ozone and potentially at an increased risk from exposure include trees such as black cherry, quaking aspen, ponderosa pine and cottonwood. These trees are found in many areas of the country. These effects can also have adverse impacts on ecosystems, including loss of species diversity and changes to habitat quality and water and nutrient cycles. Learn more about the effects of ozone on ecosystems.

Actions to Reduce Ozone

image of plant damage from ozoneThere are actions every one of us can take to keep the air cleaner, and protect your health. The following guides will help you determine ways to protect your family's health when ozone levels reach the unhealthy range, and ways you can help reduce air pollution. Learn about the steps you can take.

Ozone Good Up High Bad Nearby

Ozone: Good Up High, Bad Nearby
Ozone acts as a protective layer high above the earth, but it can be harmful to breathe. This publication provides basic information about ground level and high-altitude ozone.


Image of doctor and patient

Ozone and Your Patients' Health On-Line Training
(with CME credit available):
This is a short evidence-based course for health care providers that explains the physiological effects of ozone and ways people can reduce their exposure to ozone. It includes clinical scenarios and frequently asked questions to help counsel patients about ozone, asthma, and respiratory symptoms.


Ozone Good Up High Bad Nearby

Why is Coco Orange?
Coco has a problem. He's a chameleon, but he can't change colors, and his asthma is acting up. Read how Coco and his friends solve this mystery as they learn about air quality and how to stay healthy when the air quality is bad. This book is for all children, especially those with asthma, and their caretakers. Ages 4-8.



May 9, 2012 - Final rule waives requirements for gas pump vapor recovery.
Learn More.

April 30, 2012 - Final Approach for Establishing Nonattainment Area Classifications and Attainment Deadlines
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April 4, 2012 - EPA announces Ozone Advance to promote ground-level ozone emission reductions.
Learn More.


Ozone Formation

Learn how ozone is formed
(Flash movie)

Your Air Quality

Map showing current Air Quality Index

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