News
EPA proposes lower limits for short-term exposure to air pollutant nitrogen dioxide; American Thoracic Society urges even lower short-term limits
The US Environmental Protection Agency has proposed augmenting the existing average annual standard for nitrogen dioxide (NO2) with a new short-term standard within the range of 80-100 parts per billion (ppb). The EPA especially wants to assure that the federal requirement addresses health concerns from short term exposure of an hour or less.
The proposal would maintain the current long-term concentration requirements, monitored over a year, but establish a new standard based on one-hour monitoring.
While the annual standard of a maximum 53 parts per million nitrogen dioxide concentration in the air would remain the same, the EPA wants to limit short-term concentrations — based on hour-long monitoring — to between 80 ppm and 100 ppm to provide added protection from short-term exposure.
“Current scientific evidence links short-term exposure, ranging from 23 minutes to 24 hours, with increased respiratory effects, especially in persons with asthma,” the EPA statement said. These exposures, it said, often occur close to heavily traveled roadways and lead to increased visits to emergency rooms, hospital admissions and respiratory illnesses, particularly in children, the elderly and asthmatics.
The EPA is now accepting public comments and the final NAAQS rule for nitrogen oxides is expected to be issued by Jan. 22, 2010.
In a recent editorial, American Thoracic Society (ATS) members urged the Environmental Protection Agency (ERA) to establish a more stringent short-term standard for nitrogen oxides (NOx) to protect public health.
Authors Mark W. Frampton, MD, and Ian A. Greaves, MD, noted in the June 15 issue of the American Journal of Respiratory and Critical Care Medicine, the EPA was legally required to propose a new standard for NO2 by June 26.
“Before the 1996 evaluation of the nitrogen dioxide (NO2) standard, human clinical studies did not consistently demonstrate airway effects at exposure concentrations less than 2,000 ppb,” write Frampton and Greaves, on behalf of the ATS Environmental Health Policy Committee.
