Air Quality Index: Ozone Pollution
2007 Proposed Revisions to Ground-Level Ozone Standards by EPA
As the proposed revisions to standards of ground-level ozone pollution go into effect in 2008, understanding how ozone affects health and climate change is important.
Air Quality Index: Ozone
The Air Quality Index (AQI) provides daily air quality data that is monitored by the U.S. Environmental Protection Agency, or EPA. The air quality data represents how clean or polluted the air is for a given location. The AQI monitors five major air pollutants including:
- ground level ozone
- particle pollution
- carbon monoxide
- sulfur dioxide
- nitrogen dioxide
These major air pollutants are regulated by standards set in place by the Clean Air Act and the EPA, which issued the National Ambient Air Quality Standards (NAAQS).
What is Ground-Level Ozone?
Ozone exists naturally in the upper atmosphere, benefiting the Earth by blocking out a portion of the harmful UV rays from the sun. Ozone located in the upper atmosphere is one of the naturally occurring greenhouse gases. Ground-level ozone occurs near the Earth’s surface, where is represents a harm to people and a cause of global warming. Although ozone and ground-level ozone share the same chemical structure, the location of the gas in the atmosphere, defines it as “good” or “bad”.
The EPA describes the production of ground-level ozone as “a chemical reaction between volatile organic compounds (VOCs) and oxides of nitrogen in the presence of sunlight”. Emissions from vehicles, chemical solvents and gasoline vapors can form ozone. Sunlight and hot temperatures cause ground-level ozone to form in higher concentrations. Ground-level ozone is also known as smog.
Harmful Ground-Level Ozone Air Pollution
Ozone can cause respiratory irritation and inflammation when inhaled, especially during physical activity. Ozone can:
- worsen asthma
- affect lung function
- cause increased sensitivity to allergens and lung infections
- even cause damage to lung tissue
Ozone Action Day for Unhealth Air Quality
Sensitive groups, such as children who are active outside and people with respiratory disease, should pay close attention to the daily air quality value. Some regions may initiate an Ozone Action Day when unhealthy levels of ozone are detected. During Ozone Action Days people are encouraged to:
- conserve electricity
- limit vehicle idling if driving
- carpool, walk or bike to work
- put off using gas powered lawn mowers and garden tools
- visit gas stations after dark
- limit the use of household chemicals
Proposed Revisions to Ground-Level Ozone Standards
The Clean Air Act, last amended in 1990, regulates and set standards for air pollutants including ground-level ozone. The EPA first set standards for ground-level pollution in 1971. The Clean Air Act requires review of these standards on a periodic basis.
The latest proposed revisions to the standards came in 2007. These revisions to the current standards for ground-level ozone would strengthen standards of protecting public health. They also aim to increase prevention of damage by ground-level ozone. The Final Rule on the revisions is set for March 2008, becoming effective in June 2008.
