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Jun 21 – US: Stronger Standards for Smog Proposed

A recent news release from the EPA includes the following:

The proposal recommends an ozone standard within a range of 0.070 to 0.075 parts per million (ppm). EPA also is taking comments on alternative standards within a range from 0.060 ppm up to the level of the current 8-hour ozone standard, which is 0.08 ppm…

Ground-level ozone is not emitted directly into the air, but is created through a reaction of nitrogen oxides and volatile organic compound emissions in the presence of sunlight. Emissions from industrial facilities, electric utilities, motor vehicle exhaust, gasoline vapors, and chemical solvents are the major man-made sources of these ozone precursors.

EPA also is proposing to revise the “secondary” standard for ozone to improve protection for plants, trees and crops during the growing season. The secondary standard is based on scientific evidence indicating that exposure to even low levels of ozone can damage vegetation. EPA is proposing two alternatives for this standard: a standard that would be identical to the “primary” standard to protect public health; and a cumulative standard aimed at protecting vegetation during the growing season…

The agency will take public comment for 90 days following publication of the proposal in the Federal Register and will hold four public hearings. The hearings will be held in Los Angeles and Philadelphia on Aug. 30, and in Chicago and Houston on Sept. 5.

Information about the EPA’s ground-level ozone proposal is available at:

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