EPA Sets Stronger SO2 Standard

The U.S. Environmental Protection Agency (EPA) plans to issue a final new health standard for sulfur dioxide (SO2). According to the EPA, this one-hour health standard will protect millions of Americans from short-term exposure to SO2, which is primarily emitted from power plants and other industrial facilities. Exposure can aggravate asthma and cause other respiratory difficulties; people with asthma, children, and the elderly are especially vulnerable to the effects.

“We’re taking on an old problem in a new way, one designed to give all American communities the clean air protections they deserve,” said EPA Administrator Lisa P. Jackson. “Moving to a one-hour standard and monitoring in the areas with the highest SO2 levels is the most efficient and effective way to protect against sulfur dioxide pollution in the air we breathe. This is one of many pollutants we’ve been able to significantly reduce through the Clean Air Act, keeping people healthy, protecting our environment and growing our economy. This new standard-the first in almost 40 years-will ensure continued success in meeting these challenges.”

The EPA is setting the one-hour SO2 health standard at 75 parts per billion (ppb), a level designed to protect against short-term exposures ranging from five minutes to 24 hours. The EPA is revoking the current 24-hour and annual SO2 health standards because the science indicates that short-term exposures are of greatest concern and the existing standards would not provide additional health benefits.

Monitoring requirements for SO2 are also being changed; the new requirements ensure that monitors will be placed where SO2 emissions impact populated areas. Any new monitors required by this rule must begin operating no later than January 1, 2013. The EPA is expecting to use modeling as well as monitoring to determine compliance with the new standard.

The final rule also changes the Air Quality Index to reflect the revised SO2 standard. This change will improve states’ ability to alert the public when short-term SO2 levels may affect their health.

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