From: David A Gabel, ENN
Published June 3, 2010 02:36 PM

EPA Takes a New Stance on Sulfur Dioxide in Final Rule

Sulfur Dioxide (SO2) is a highly reactive gas that is produced from the combustion of fossil fuels. The largest sources of SO2 are power plants (73 percent) and other industrial facilities (20 percent). The gas is strongly linked to negative effects on the human respiratory system such as asthma. Children, the elderly, and those already with asthma are particularly vulnerable to its effects. The US Environmental Protection Agency (USEPA) says the new one-hour health standard will protect millions of citizens from short-term SO2 exposure.


Standards on SO2 by the EPA were first established in 1971. The EPA set a 24-hour primary standard at 140 parts per billion (ppb) and an annual average standard at 30 ppb. This was thought to be sufficient for protecting the public health and welfare. The standards were examined again in 1996 during deliberations on the overall National Ambient Air Quality Standards (NAAQS). However, the EPA chose at the time not to revise the standards for SO2.

Now, the EPA is revising the one-hour SO2 standard at 75 ppb. They are also revoking the existing 24-hour and annual average standards. The new level is designed to protect against short-term exposures because the science indicates the greatest concern is from exposure during shorter periods. EPA claims the new standards will provide additional health benefits over the existing standards.

EPA has released the following estimates as to the benefits and costs associated with the new standards:

- Health benefits - $13 billion to $33 billion annually
- Premature deaths – 2,300 to 5,900 less
- Asthma attacks – 54,000 less
- Cost to fully implement standard in 2020 - $1.5 billion

"We're taking on an old problem in a new way, one designed to give all American communities the clean air protections they deserve. 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. "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."

Monitoring programs will have to change. The new rule requires ambient air quality monitors to be placed where SO2 emissions impact populated areas. New monitors required by the standards must begin operation by January 1, 2013 at the latest. To determine compliance, EPA expects to use this monitoring as well as modeling of SO2 emissions. The revised monitoring programs will also be reflected in an updated Air Quality Index. This will improve the states' ability to alert the public of health-adverse short-term levels of SO2.

The new rule set by the EPA is another example of steps taken to reduce pollution by the federal agency, which has become much more proactive under the new administration. Taking it in as a larger picture, one can see these moves as an effort to gradually shift America away from the combustion of fossil fuels to a clean energy future. More steps are sure to come in the future.

For more information:

EPA press release

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