EPA releases new one-hour health standard for SO2

For the first time in nearly 40 years, the U.S. Environmental Protection Agency (EPA) has issued a new health standard for sulfur dioxide (SO2).

The EPA is changing 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 agency is also revoking the current 24-hour and annual SO2 health standards because research indicates that short-term exposures are of greatest concern.

In addition, the EPA is changing the monitoring requirements for SO2 to 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 Jan. 1, 2013, the EPA said. The agency expects to use modeling as well as monitoring to determine compliance with the new standard.

“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,” said EPA Administrator Lisa P. Jackson.

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

The final rule addresses only the SO2 primary standards, which are designed to protect public health. EPA will address the secondary standard – designed to protect the public welfare, including the environment – as part of a separate review to be completed in 2012.

The EPA estimates that the health benefits associated with this rule range between $13 billion and $33 billion annually. These benefits include preventing 2,300 to 5,900 premature deaths and 54,000 asthma attacks a year.

EPA expects to identify or designate areas not meeting the new standard by June 2012.