TCS Daily

Particle Civics

By Joel Schwartz - January 4, 2006 12:00 AM

When the Environmental Protection Agency cuts allowable particle pollution levels more than 45 percent, you might expect commendations from environmentalists and the press. You'd be disappointed.

EPA recently proposed reducing allowable daily levels of fine particulate matter (PM2.5) from 65 micrograms per cubic meter (ug/m3) down to 35 ug/m3. The change would nearly double the number of pollution monitoring locations that violate federal PM2.5 standards.[i]

Environmentalists were unimpressed. Clean Air Watch complained "President Bush Gives Early Christmas Present to Smokestack Industries."[ii] According to the American Lung Association "EPA Proposes 'Status Quo' Revisions to PM [Standards]."[iii]

Some newspapers didn't do any better. The Atlanta Journal-Constitution's front-page headline claimed "EPA barely budges on soot; Health advice disregarded."[iv] According to the New York Times, EPA "modestly" reduced allowable PM2.5, and "largely ignored recommendations for tighter controls from its own scientists and from an independent panel of outside experts."[v]

A more realistic assessment is that EPA substantially tightened its PM2.5 standard, but by a bit less than its science advisory panel recommended, and not by nearly as much as environmentalists wanted. That this could be called "status quo" is a mark of how detached from reality the bizarre world of air pollution politics has become.

EPA has two standards for fine particulates, or PM2.5. An annual-average limit of 15 ug/m3, and a daily limit of 65 ug/m3.[vi] Both were adopted by the Clinton administration in 1997. EPA is proposing to keep the annual standard the same, but to lower the daily PM2.5 limit from 65 to 35 ug/m3.

Currently, the annual standard is what's driving PM2.5 regulation. Fourteen percent of the nation's PM2.5 monitoring locations violate the annual standard, while only 0.3 percent violate the daily standard. But under EPA's new proposal, the daily standard would set the pace, nearly doubling the PM2.5 violation rate to 27 percent of all monitoring sites, including turning virtually all annual violators in daily violators as well, and adding about 75 additional counties to EPA's list of PM2.5 "non-attainment" areas.[vii]

EPA's Clean Air Science Advisory Committee (CASAC), a group of outside scientists and health experts, recommended somewhat tougher standards than EPA proposed—a 30 ug/m3 daily limit, and a 13-14 ug/m3 annual limit. Activists wanted EPA to go further still. The Lung Association pressed for a daily standard of 25 ug/m3 and an annual of 12 ug/m3.[viii] This would have put about 75 percent of America's metropolitan areas in violation of the standards. Although EPA didn't go as far as CASAC recommended, calling EPA's proposal "status quo" is a gross misrepresentation.

Environmentalists are also creating the false impression that current standards are weak and that little is being done to reduce particulate matter. For example, John Balbus of Environmental Defense claimed "The old standard was so weak that there was room to lower the number without actually making big improvements on the ground."[ix]

In reality, 35 percent of the nation's PM2.5 monitors exceeded the annual PM2.5 standard in 1999 -- the year that EPA began national PM2.5 monitoring, and two years after EPA adopted the standard. Only the 8-hour ozone standard had a higher violation rate. And regardless of where the standard is set, "big improvements" have indeed occurred on the ground. Average PM2.5 levels dropped 15 percent from 1999 to 2004.

Frank O'Donnell of Clean Air Watch pilloried the new standards for "not requiring any additional cleanup from the power industry beyond what's already planned under earlier, industry-friendly rules."[x] O'Donnell fails to mention that those ostensibly "industry-friendly" power-plant rules reduced sulfur dioxide (SO2) emissions nearly 33 percent between 1990 and 2003, and require future SO2 emissions to be reduced another 77 percent below 2003 levels.[xi] SO2 is by far the largest source of industrial PM2.5 in the eastern U.S., and existing requirements will get rid of most of it.

A small amount of industrial PM2.5 also comes from emissions of oxides of nitrogen (NOx). But additional "industry-friendly" rules reduced annual power plant NOx emissions by 30 percent between 1998 and 2004, and 60 percent during May-September.[xii] EPA's Clean Air Interstate Rule requires additional power-plant NOx reductions in the future. EPA has also adopted rules that will eliminate almost all remaining PM2.5 from automobiles, diesel trucks, and off-road diesel equipment, as well as PM2.5 from other industries besides power plants.[xiii]

It is possible that EPA's tougher PM2.5 standard won't require any new emission-reduction requirements in some metropolitan areas. If so, it won't be because the new standard is lax, but because EPA has already clamped down so severely on the major sources of PM2.5 that no additional regulations would be necessary. Leave it to environmentalists to turn the stringency of past regulations into an apparent liability.

Environmentalists and even health experts on EPA's CASAC advisory panel are also using EPA's failure to reduce the annual PM2.5 standard to justify the false claims that EPA maintained the "status quo" on PM2.5 and "ignored" CASAC's advice.

What both the activists and scientists, and the journalists who quote them, fail to realize is that tightening the daily PM2.5 standard will effectively tighten the annual PM2.5 standard as well. After all, annual PM2.5 levels are just an average of daily levels, and most measures to reduce PM2.5 on the worst days also reduce PM2.5 on all other days (and vice versa). Low-emitting cars and trucks are low-emitting all the time, not just on a few days expected to have high PM2.5 levels.

That reductions in short-term and long-term PM2.5 occur in concert is easy to verify with data collected over the last few years. Between 1999 and 2004, annual-average PM2.5 levels declined 15 percent, while PM2.5 levels on the worst days declined 14 percent. Similarly, since the early 1980s, annual-average PM2.5 levels have declined about 45 percent, while peak daily levels declined nearly 50 percent.[xiv]

As a result of the relationship between daily and annual-average PM2.5 levels, reducing the daily standard from 65 to 35 ug/m3 will have the effect of reducing the annual standard at least to CASAC's recommended level of 13-14 ug/m3, and perhaps even to the 12 ug/m3 standard the Lung Association wanted.

The debate over where EPA should set PM2.5 standards also confuses process -- the standards -- with the actual measures that reduce PM2.5. The fact that federal air pollution regulations are generally national or at least multi-state in scope means that PM2.5 will continue to go down all over the U.S., including in places that already comply with EPA's proposed standards.

Could public debate on air pollution be any more absurd? EPA proposes a new standard that would reduce allowable peak PM2.5 levels by 45 percent and that would double the national PM2.5 non-attainment rate. Yet environmentalists call this "status quo" with a straight face, health scientists claim EPA ignored their recommendations, and journalists endorse these false assessments.

Environmentalists then criticize the standard on the grounds that it might not require adoption of any new regulations, ignoring that this could only be true if EPA had already adopted regulations sufficiently demanding to attain the new standard. Perhaps next time environmentalists would be appeased if EPA instead delayed any actual pollution reductions until after a new standard is adopted.

Polls continue to show that most Americans mistakenly believe air pollution has been worsening and that too little is being done to improve air quality. With our current band of "reliable sources" for air pollution information, is it any wonder?

Joel Schwartz is a visiting fellow at the American Enterprise Institute. The second article in this series will focus on PM2.5 and health.


[i] Unless otherwise noted, information on PM2.5 levels, trends, and violation rates comes from national PM2.5 monitoring data downloaded from EPA at percent20States. Violation analyses are based on monitoring sites with complete data for 2002-04 (attainment of the standard is based on three-year averages of pollution levels), while trends are based on sites with complete data for 1999-2004.

[ii] See

[iii] See

[iv] Jeff Nesmith, "EPA barely budges on soot; Health advice disregarded," Atlanta Journal-Constitution, December 21, 2005, 1A.

[v] Michael Janofsky, "Regulations Are Proposed to Cut Back Particulates," New York Times, December 21, 2005.

[vi] The daily standard is based on the three-year average of the 98th percentile of daily readings. In practice, this means that a given monitoring site can average about 7 days per year with PM2.5 above 65 ug/m3 before it violates the standard.

[vii] For EPA's estimates of the increases in non-attainment counties, see These estimates are based on 2002-2004 data, which are the most recent available. Actual regulatory designations of non-attainment areas under the new standard will of course depend on future PM2.5 levels, probably levels during 2006-2008.

[viii] From ALA's press backgrounder on the new standards. ALA also wanted the daily standard to be based on the 99th percentile, rather than the 98th.

[ix] Quoted in the Washington Post, December 21, 2005.

[x] Frank O'Donnell, "The Unfriendly Skies," December 20, 2005,

[xi] The reductions through 2003 occurred under the Clean Air Act's Title IV acid rain requirements. Future reductions are required by EPA's recently adopted Clean Air Interstate Rule.

[xii] These rules are the NOx Budget Trading Program and the NOx SIP Call.

[xiii] In discussing PM2.5 reductions here, I mean both direct PM emissions, and emissions of PM2.5-forming gases, such as NOx, and volatile organic compounds. For a summary of regulatory requirements with links to primary sources, see my TCS column "New Source of Confusion."

[xiv] Based on comparison of PM2.5 data collected by the Inhalable Particulate Monitoring Network, which operated from 1979-83, with data collected since 1999.



Show me the data
Personally, I would want no more tightening of the standards until it can be shown that the reductions since 1999 have actually produced the expected benefits in reduced mortality and morbidity.

Witty title
Nice piece that captures explains (1) the just a piece of the progress that's been made over the last several years and that more is to come, and (2) the insanity that continues on the part of one segment of the society.

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