Friday, July 02, 2010

EPA scientists call for much tougher air standard to limit fine particle soot

This is not the sort of information best made public at the start of a holiday weekend, but here it is:

EPA’s professional staff has concluded that national air pollution standards for fine particle soot must be made considerably tougher.

The EPA “policy assessment” was posted on the Internet a short while ago at

Here is a key passage from the executive summary:

Primary standards for fine particles (Chapter 2):

In assessing the adequacy of the current suite of annual and 24-hour PM2.5 standards meant to protect public health against long- and short-term exposures to fineparticles, staff concludes that the currently available information clearly calls into question the adequacy of the current standards and that consideration should be given to revising the suite of standards to provide increased public health protection. In considering alternative PM2.5 standards, staff concludes that protection from both long and short-term PM2.5 exposures can most effectively and efficiently be provided by relying primarily on the annual standard, with the 24-hour standard providing supplemental protection for days with high peak concentrations. On this basis, staff concludes that consideration should be given to alternative annual PM2.5 standard levels in the range of 13 to 11 μg/m3, in conjunction with retaining the current 24-hour PM2.5 standard level of 35 μg/m3, and that consideration could also be given to an alternative 24-hour PM2.5 standard level of 30 μg/m3 particularly in conjunction with an annual standard level of 11 μg/m3.

This is a very significant development. You will recall that the Bush EPA rejected the advice of agency science experts and kept the all-important annual standard at a level of 15 (compared to the levels of 11-13 recommended by EPA’s staff now).

The EPA lost a lawsuit over those inadequate standards and is now working on a likely revision next year. This policy assessment is meant as a guide to help the EPA higher-ups distill the copious information.

Should EPA follow the advice of its own experts, it means we will need much tougher controls on the biggest sources of fine particle soot, including coal-burning electric power plants and the millions of dirty diesel engines still in service.

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