EPA’s Ground-level Ozone Standard

Air Quality

Air Quality Forecast & Agricultural Burn Status

Air Quality Index

Air Quality Standards

Air Quality Statistics

EPA’s New Standard for Ground-level Ozone

On March 12, 2008, the U.S. Environmental Protection Agency (EPA) strengthened the National Ambient Air Quality Standard (NAAQS) for ground-level ozone, the primary constituent of smog. Specifically, EPA revised the primary and secondary 8-hour ozone standards to 0.075 parts per million (ppm). The previous standard (the 1997 standard) was 0.08 ppm. EPA estimates that the revised standards will yield health benefits valued between $2 billion and $17 billion. Those benefits include preventing cases of bronchitis, aggravated asthma, hospital and emergency room visits, nonfatal heart attacks and premature death, among others.

On September 16, 2009, EPA announced it would reconsider the 2008 NAAQS for ground-level ozone to ensure that the nation’s most important air quality standards are clearly grounded in science, protect public health with an adequate margin of safety, and protect the environment. The ozone standards set in 2008 were not as protective of public health as recommended by EPA’s panel of science advisors, the Clean Air Scientific Advisory Committee (CASAC). The reconsideration is being based on the scientific and technical record used for the March 2008 review, which included more than 1,700 scientific studies.

On January 6, 2010, EPA proposed to strengthen the 8-hour primary ozone standard to a level within the range of 0.060 - 0.070 ppm. On December 8, 2010, EPA Administrator Jackson asked the CASAC for further information regarding the epidemiological and clinical studies they used to make their recommendation on setting the level of the standard. EPA intends to set a final standard in the range recommended by the CASAC by the end of July, 2011.

Along with EPA’s action in March 2008 to strengthen the ozone NAAQS, EPA also revised the Air Quality Index (AQI) for ozone to reflect the new, more stringent standard. The AQI is a color-coded chart designed to inform the public about daily air pollution levels in their communities.

 

Category

AQI Value

1997
8-hour (ppm)

2008
8-hour (ppm)

GOOD

0-50

0.000-0.064

0.000-0.059

MODERATE

51-100

0.065-0.084

0.060-0.075

UNHEALTHY FOR
SENSITIVE GROUPS

101-150

0.085-0.104

0.076-0.095

UNHEALTHY

151-200

0.105-0.124

0.096-0.115

VERY UNHEALTHY

201-300

0-125-0.374

0.116-0.374

 

As part of the Ventura County APCD’s mission to improve Ventura County’s air quality and provide timely information to the public, the APCD uses the AQI to inform the public about the county’s air quality. Click here to see the current air quality forecast for Ventura County.
 

How do these changes affect Ventura County?

On June 15, 2004, EPA designated Ventura County as a moderate nonattainment area for the 1997 8-hour ozone standard, based on Ventura County’s ozone levels over the previous three years. However, on February 14, 2008, ARB formally requested that EPA reclassify Ventura County up one classification level to a serious 8-hour ozone nonattainment area. On May 20, 2008, EPA approved the reclassification request, which became effective June 19, 2008. Therefore, Ventura County is now a serious ozone nonattainment area, and must meet the federal 8-hour ozone standard by June 15, 2013.

As of March 13, 2008, the APCD began reporting the County’s ozone levels using the new ozone Air Quality Index. The use of the new AQI is more protective of the public’s health and will result in more days being shown with an increased AQI.
 

For more information:

EPA's website for regulatory actions related to the ozone standards is:
http://www.epa.gov/groundlevelozone/actions.html

Click here to see a map of counties with monitors violating proposed primary 8-hour ground-level ozone standards (0.060 - 0.070 parts per million).*

Click here to see a map of counties with monitors projected to violate proposed primary 8-hour ground-level ozone standards (0.060 - 0.070 parts per million) in 2020.*

* These slides are from the following EPA presentation http://www.epa.gov/groundlevelozone/pdfs/20100104maps.pdf