Tuesday, April 19, 2011

US EPA staff: we need much tougher national standard for fine particle soot

US EPA professionals are calling for much tougher national clean air standards for fine-particle soot.

The call came in a final “policy assessment” regarding new clean air standards for soot in the air. This is a critical step as the agency moves to set new national standards.

Tougher standards would underscore the need to do more to clean up the biggest sources of fine particle soot, including coal-burning power plants and diesel engines.

You may recall a bit of the history: in 2006, the Bush EPA set standards that ignored the advice of the agency’s science advisers. Most important, the EPA left the critical annual average standard for fine particle soot where it had been before – at 15 micrograms per cubic meter.

Some state, environmental and health groups sued, and a federal court agreed that the EPA had been “arbitrary and capricious” in setting a standard that ignored the advice of the science advisers, who had recommended a lower level to protect people’s health.

As a result, the Obama EPA agreed to move ahead and review the latest science with an eye towards revising the standards.

As you may recall, the agency’s science advisers strongly recommended a tougher annual standard. And now the EPA professionals are on record agreeing. The next step in this process is an actual proposal by the EPA to change the current standards.

We hope EPA moves quickly on this issue because fine-particle soot is literally a killer. It shortens peoples’ lives and can make them very sick.


Below are excerpts of the report, which can be found here: http://www.epa.gov/ttn/naaqs/standards/pm/data/20110419pmpafinal.pdf

On tiny, so-called “fine” particles:

Taking into account both evidence-based and risk-based considerations, staff concludes that consideration should be given to revising the current annual PM2.5 standard level of 15 μg/m3 to a level within the range of 13 to 11 μg/m3. Staff further concludes that the evidence most strongly supports consideration of an alternative annual standard level in the range of 12 to 11 μg/m3. [my emphasis added]

In conjunction with consideration of an annual standard in the range of 12 to 11 μg/m3, staff concludes it is appropriate to consider retaining the current 24-hour PM2.5 standard level at 35 μg/m3. In conjunction
with consideration of an annual standard level of 13 μg/m3, staff concludes there is limited support to consider revising the 24-hour PM2.5 standard level to somewhat below 35 μg/m3, such as down to 30 μg/m3.

The EPA professionals also looked at the issue of bigger particles, or “coarse” particles in the jargon of the bureaucracy. In this case, they’ve recommended a lower standard, but one that would permit more days of dirty air under that new standard. We are still examining this, but believe in fact it could actually constitute a weakening of current standards. As you may know, the “coarse” particle standard has come under fire by the farm lobby and its noisy supporters in Congress.

On “coarse” particles:

To the extent consideration is given to revising the current standard, which has a one-expected-exceedance form and a level of 150 μg/m3, staff concludes that consideration should be given to revising both the form and level. In this case, consideration should be given to a 98th percentile form and a level within the range of 85
μg/m3 down to about 65 μg/m3, in conjunction with retaining the PM10 indicator and the 24-hour averaging time. Staff also concludes that standard levels in the upper part of this range are supported by the strongest evidence.

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