AG 2007 10 15 - Laserfiche WebLink

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FACT SHEET PROPOSAL TO REVISE THE NATIONAL AMBIENT AIR QUALITY STANDARDS FOR OZONE ACTION • On June 20, 2007, EPA proposed to strengthen the national ambient air quality standards for ground-level ozone, the primary component of smog. The proposed revisions reflect new scientific evidence about ozone and its effects on people and public welfare. • Breathing air containing ozone can reduce lung function, thereby aggravating asthma or other respiratory conditions. Ozone exposure has also been associated with increases in respiratory infection susceptibility, medicine use by asthmatics, doctors visits, emergency department visits and hospital admissions. Ozone exposure also may contribute to premature death in people with heart and lung disease. • Scientific evidence indicates that adverse public health effects occurs following exposure to ozone at levels below the current standard, particularly in those with respiratory illnesses. • In addition, new scientific evidence since the last review shows that repeated exposure to low levels of ozone damages vegetation, trees and crops, leading to increased susceptibility to disease, damaged foliage, and reduced crop yields. • EPA's proposal would revise both ozone standards: the primary standard, designed to protect human health; and the secondary standard, designed to protect welfare (such as vegetation and crops). The existing primary and secondary standards, set in 1997, are identical: an 8- hour standard of 0.08 parts per million (ppm). (In practice, because of rounding, an area meets the standard if ozone levels are 0.084 ppm or lower.) Proposed revisions to the primary standard • EPA proposes to set the primary (health) standard to a level within the range of 0.070-0.075 ppm (70 -75 ppb). The Agency also requests comments on alternative levels of the 8-hour primary ozone standard, within a range from 0.060 ppm up to and including retention of the current standazd (0.084 ppm). (EPA also proposes to specify the level of the primary standard to the third decimal place, because today's monitors can detect ozone that accurately.) Proposed revisions to the secondary standard • EPA is proposing two options for the secondary standard: • One option would establish a new form of the standard designed specifically to protect sensitive plants from damage caused by repeated ozone exposure throughout the growing season. This cumulative standard would add daily ozone concentrations across athree-month period. EPA is proposing to set the level of the cumulative standard within the range of 7 to 21 ppm-hours. ~--' ~ "~