Tuesday, June 12, 2012

A reader's guide to EPA particle soot standards: the sleeping giant of clean air issues

By late this week, the US EPA is expected, under a court order, to set forth proposed national clean air standards for fine particle soot.

This is the sleeping giant of clean air issues. EPA’s decision could frame the clean-air agenda for the next decade and possibly beyond. EPA’s own experts and the agency’s science advisers have concluded that the current standards are woefully inadequate. Tougher standards could drive the need for additional cleanup.

I thought this brief reader’s guide might be of some use in evaluating what EPA does.

First of all, why do we care about fine particle soot (known in the world of jargon as pm 2.5)?

Particle soot is without a doubt the most lethal of widespread air pollutants. Fine particle soot has been linked to tens of thousands of premature deaths year as well as lung disease, heart attacks, etc.

Here is a brief description, courtesy the U.S. EPA:

Health studies have shown a significant association between exposure to fine particles and premature mortality. Other important effects include aggravation of respiratory and cardiovascular disease (as indicated by increased hospital admissions, emergency room visits, abscesses from school or work, and restricted activity days), lung disease, decreased lung function, asthma attacks, and certain cardiovascular problems such as heart attacks and cardiac arrhythmia. Individuals particularly sensitive to fine particle exposure include older adults, people with heart and lung disease, and children.

Where does particle soot come from?

Again, from the EPA:

Sources of fine particles include all types of combustion activities (motor vehicles, power plants, wood burning, etc.) and certain industrial processes. Particles with diameters between 2.5 and 10 micrometers are referred to as "coarse." Sources of coarse particles include crushing or grinding operations, and dust from paved or unpaved roads.
Hasn’t the EPA been dealing with this issue through other rules, such as its Cross-State Air Pollution Rule? http://www.epa.gov/crossstaterule/

Yes, the cross-state air pollution rule is a tool to help states deal with pollution that blows in from other states and to help them meet air quality standards for smog and fine-particle soot. The key difference is that the air quality standard (known in the jargon as the NAAQS or National Ambient Air Quality Standard) limits atmospheric concentrations. It sets a health-based target for what legally constitutes healthful air. Rules such as cross-state are a means to achieve that end.

But please keep in mind that the cross-state rule is designed to achieve the existing air quality standard, which is not truly adequate to protect people’s health. A tougher new air quality standard could drive the need for additional cleanup. (The Clean Air Act requires the EPA periodically to review the medical science and update the air quality standards, as needed, to protect people’s health.)

What’s the brief history of the particle soot air standard?

In 2006, the Bush administration’s EPA disregarded the advice of EPA’s science advisers and failed to tighten the critical standard designed to limit annual exposure to fine-particle soot. (EPA then kept the standard, set in 1997, at 15 micrograms per cubic meter. See chart below. The sciences advisors had recommended a tighter standard.

In fact, the 2006 Bush plan was so scientifically deficient that the agency’s science advisers publicly scolded the agency – an unprecedented rebuke: http://www.redorbit.com/news/science/441066/clean_air_advisors_to_epa_reconsider_your_weak_particle_soot/

Thirteen states and several environmental groups challenged the 2006 standards as too weak, based on the medical science. In 2009, a federal appeals court agreed and ordered EPA to go back to the drawing board. The current air standard review is a product of that court decision.

EPA initially promised it would review recent science and issue a final decision in 2011. After months of EPA indecision, states led by New York filed suit to force a decision. http://blogforcleanair.blogspot.com/2012/02/big-thanks-to-states-led-by-ny-which.html The American Lung Association and National Parks Conservation Association filed a similar suit. A federal court eventually ordered EPA to sign a proposal by the end of this week and to issue a final standard by mid-December of this year.

What are EPA’s own experts and its science advisers recommending?

EPA’s experts have recommended a considerably tougher new standard to limit annual concentrations of fine particle soot in the air.

EPA’s final “policy assessment” was completed in April 2011.

Here are a few key excerpts:
…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.

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. 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.

…Based upon the currently available evidence, we conclude alternative annual standard levels in the range of 13 to 11 μg/m3 are appropriate to consider. We further conclude that the evidence most strongly supports consideration of an alternative annual standard level in the range of 12 to 11 μg/m3. An alternative level within the range of 12 to 11 μg/m3 would more fully take into consideration the available information from all long- and short-term PM2.5 exposure studies, including studies of susceptible populations, than would a higher level.

What about EPA’s independent science advisers?

The science advisers agree a tougher standard is needed. Here is their letter and some excerpts below:


CASAC supports the EPA staff’s conclusion in the Second Draft Policy Assessment that “currently available information clearly calls into question the adequacy of the current standards”. For PM2.5, the current 24-hour primary standard is 35 μg/m3 and the annual standard is 15 μg/m3. EPA staff also conclude that consideration should be given to alternative annual PM2.5 standard levels in the range of 13 – 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 in conjunction with an annual standard level of 11μg/m3.

What about the politics of this issue?

You may recall the flap over “farm dust.” The EPA is also reviewing standards for larger particles. Farm groups and their political sponsors alleged the EPA would regulate “farm dust” and threaten farmers. EPA chief Lisa Jackson was forced to publicly declare EPA would not seek to regulate “farm dust.”

Even so, Senate Majority Leader Mitch McConnell says he will press farm legislation amendments to block EPA.
On the other side of Capitol Hill, Reps. Upton, Barton and Whitfield last week called on EPA to include consideration of keeping current standards. It is not hard to see the sooty hand of the coal-burning power industry in this letter:

What are the current standards for fine-particle soot?

There are currently two standards: one to limit annual concentrations, the other to limit 24-hour exposure.

PM2.5 primary and
secondary Annual 15 μg/m3 annual mean, averaged over 3 years
24-hour 35 μg/m3 98th percentile, averaged over 3 years

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