Revised Ozone Standard Due by March 12, 2008

March 5, 2008

More than a decade after the federal standard for ground-level ozone was last updated, EPA is scheduled to announce by March 12, 2008, its final rule for a new standard (likely to be posted here). If there are no lawsuits that delay its implementation, there will then be a series of deadlines, from June 2009 to 2013, for states to determine what areas don't meet the standard, submit plans for bringing those areas into compliance, and begin implementing those plans (fact sheet).

Information released during the most recent public comment period (which began in June 2007) indicates that the standard could be little changed from its current level of 80 ppb, or might be somewhat lower, in the range of 70-75 ppb. Many public health officials are pushing for a more protective standard of about 60 ppb. EPA scientific evidence indicates that some people can be harmed at levels as low as 40 ppb.

If the standard is made more protective, more US cities and counties likely will be considered out of compliance, and could face substantial economic penalties, such as the loss of federal funds. For a list of counties currently tagged as "nonattainment," see EPA's 8-Hour Ground-level Ozone Designations.

EPA uses monitors on the ground to measure ozone in cities and a few remote locations around the country. Based on this data, the general trend appears to be that ozone problems are largely confined to California and much of the East. However, large swaths of the western US don't have monitors, resulting in the impression on databases such as AIRNow that there are no ozone problems in most of the West.

A new national-scale tool developed by EPA and NOAA brings that into question. This ozone forecasting model has shown elevated concentrations of ozone, in the general range of 50-60 ppb, in vast swaths over much of the interior West throughout the winter. In some locations, the levels are much higher. The current standard was exceeded by about 50% in western Wyoming on Feb. 27, 2008, likely due to emissions from thousands of natural gas wells and processing facilities in the area. Many parts of the interior West are now home to such massive well fields.

In many locations in the interior West, ozone concentrations are often elevated in cold temperatures, day and night. This is contrary to EPA's assertion that both heat and sunlight are needed for harmful concentrations of ozone to form from its precursor chemicals, such as nitrogen oxides and volatile organic compounds (although there often is plenty of sunlight during the day in these areas).

There is little information on whether exposure to these concentrations 24/7 poses a different threat than do intermittent exposures during a day, or whether exposure to these concentrations year-round is any riskier than to higher concentrations during part of the year and lower concentrations for the remainder, as appears to occur in much of the eastern half of the country.

Another potentially important and little-recognized or -studied revelation offered by this site is that vast swaths of ocean, hundreds of miles off our Atlantic, Gulf, and Pacific shores, are frequently overlain by ozone at elevated concentrations, again in the general range of 50-60 ppb. It's uncertain how this may be affecting ocean chemistry and biology.

The information on this Web site is new, and there isn't even one year of data, since it began operating in September 2007. But when the new standard comes out, it may be useful to begin looking at this data and asking questions about what these patterns may mean.

From an even larger perspective, ground-level ozone concentrations worldwide are estimated to be about double what they were just a century ago.

  • "A Review of Surface Ozone Background Levels and Trends," by Roxanne Vingarzan, Atmospheric Environment, July 2004 (abstract).

Dozens of groups will likely weigh in when the proposed standard is announced. Among those noted by Clean Air Watch's Frank O'Donnell, 202-302-2065, as being actively engaged in recent meetings with EPA are the Edison Electric Institute, the National Association of Manufacturers, the Alliance of Automobile Manufacturers, the American Chemistry Council, the Renewable Fuels Association, the Corn Refiners Association, the National Corn Growers, the American Petroleum Institute, and the US Chamber of Commerce.

Others include the American Lung Association, the American Academy of Pediatrics, the American Public Health Association, the American Thoracic Society, Environmental Defense, the Natural Resources Defense Council, Earthjustice, and Physicians for Social Responsibility.

Among interested government organizations are the National Association of Clean Air Agencies, the Environmental Council of States, the National Governors Association, the Northeast States for Coordinated Air Use Management, and the US Conference of Mayors.

For more information, see TipSheets of Oct. 10, 2007; and May 23, 2007.