Smog Declines Still Further from 2003 Record Lows

Published February 1, 2005

In 2004, the United States reported the lowest ozone smog levels since states began measuring them in the 1970s. Based on preliminary data from around the country, the number of days exceeding EPA’s tough new eight-hour ozone standard declined to an average of about 50 percent below 2003, which was itself a record low year.

A combination of continuing emission reductions and favorable weather explains the improvements. Weather is the single largest factor affecting year-to-year variations in smog levels. All else equal, cool, wet, and windy years will have less ozone than warm, dry, and calm ones.

But weather is only part of the story. During the past 30 years, most of the country has had several years that were cooler and/or wetter than 2004, but never have smog levels been anywhere near this low.

Long-Term Smog Reduction

The charts accompanying this article suggest how extraordinary 2004 was. Figure 1 shows the average number of days per year that exceeded EPA’s one-hour and eight-hour ozone standards at the nation’s ozone monitoring sites from 1975 to 2003. The eight-hour standard is much more stringent than the level that is allowed to be sustained for one hour.

Smog 1

For each standard, the chart includes the exceedance rate for all sites operating in any given year (generally about 700 to 1,200), and also for the 261 sites that operated continuously in 1983-2003. The percentages at the right of the graph indicate the decline in the number of eight-hour and one-hour exceedances since 1975.

Note that 2003 was the best year on record, barely edging out 2000, and that the average number of eight-hour ozone exceedances varies greatly from year to year. Annual variations in weather create the large short-term variability in smog levels, but superimposed on this is a long-term decline in ozone exceedances due to emission reductions.

Smog 2

Figure 1 can’t be extended through 2004 until all states have reported their 2004 ozone data. However, preliminary data for 2004 are available on the Web for several metropolitan areas and states.

Figure 2 compares eight-hour ozone exceedances in 2003 and 2004 for several of those areas. For each area, the chart gives the average number of eight-hour ozone exceedances for all monitoring locations that have reported data for both years.

Figure 3 provides data for the worst location in each of the areas in Figure 2.

Smog 3

Note the large declines almost across the board. I wasn’t able to locate data for the Midwest in time for this article, but EPA’s Web site reports there wasn’t a single “ozone action day” in 2004 in all of Illinois, Michigan, Minnesota, Ohio, and Wisconsin, while southern Indiana (the portion in the Louisville, Kentucky, metro area) had just one.

Overall, eight-hour ozone exceedance days declined by an average of about 50 percent between 2003 and 2004, meaning 2004 is not only the best year on record, but the best by a large margin.

Biased Press Misleading Public

You wouldn’t know this from reading activists’ reports on air quality, which continue to tell a deceitfully gloomy story. Dangerous Days of Summer from Environmental Defense (ED) and Danger in the Air from the Public Interest Research Group (PIRG) are the two latest entries. Neither report mentions that 2003 and 2004 were the best years in history for ozone.

PIRG does mention that 2003 and 2004 were better than 2002, but attributes it all to weather.

Nevertheless, as you might expect, activists are always ready with a press release in years when measured air pollution rises. When ozone levels spiked upward during the hot, dry summer of 2002, a Clean Air Trust press release proclaimed “New Survey Finds Massive Smog Problem in 2002.” But no activist press releases highlighted the spectacular decline in ozone levels the next year, nor the record-low ozone levels of the past two years.

Other potential but unmentioned contributors to the recent ozone improvements are a 60 percent reduction in coal-fired power plant NOx emissions during the May-September “ozone season,” implemented in May 2004 under EPA’s NOx SIP Call regulation, and an ongoing reduction of about 8 percent per year in total automobile emissions due to fleet turnover to cleaner vehicles.

Activists avoid mentioning these reductions because they undermine claims that urban “sprawl” increases air pollution and that power-plant emissions are increasing.

Full Range of Deceptions

ED’s Dangerous Days commits the full range of deceptions pioneered by the American Lung Association (ALA) in its annual State of the Air series, such as: inflating pollution levels, exaggerating the harm from current air pollution levels and the number of people living in areas that exceed EPA standards, downplaying positive trends, and creating the impression that there will be little or no future improvement without stringent new regulations.

For example, Dangerous Days claims the New York metro area exceeded the eight-hour ozone standard on 22 percent of summer days during 2001-2003. But the average site in the New York area exceeded the eight-hour standard on 10 percent of summer days–less than half of ED’s claim.

ED’s number is higher than even the worst site in the New York area (Jackson Township, New Jersey), which exceeded the eight-hour standard 20 percent of the summer. ED likewise inflated ozone levels in all of the rest of the country’s metro areas.

But Environmental Defense’s ozone inflation is even worse than this, because most people in the New York area live in places with the lowest ozone levels. Monitoring sites in the five boroughs of New York City averaged 3.7 percent of summer days exceeding the eight-hour standard, or 1/6th of ED’s claim.

Likewise, ED claimed Los Angeles exceeded the eight-hour standard on 50 percent of summer days. But about half of Angelenos live in areas that never exceeded the eight-hour standard–not once. ED also fails to distinguish between moderate and high ozone. Most ozone exceedances involved relatively low ozone levels.

The average site in the New York metro area exceeded the higher, one-hour ozone standard on only 2 percent of summer days, compared with 10 percent for the eight-hour standard.

Exaggerating the Affected Population

Dangerous Days also exaggerates the number of people who live in areas that violate EPA’s air standards. According to the report, “Nearly 160 million Americans live in areas where ozone smog levels exceed national standards. … Some 99 million Americans live in areas that exceed annual fine particle standards.”

Both of these numbers are based on the populations of entire counties designated as “non-attainment” areas by EPA. But that has little to do with actual pollution levels where people live, because EPA designates whole regions as non-attainment areas even if only a single monitoring location violates a federal standard.

That makes sense for air quality planning, but not for determining human exposure to air pollution. Thus, 94 to 99 percent of people in Chicago, Los Angeles, Phoenix, and San Diego live in areas that meet all EPA ozone standards, but EPA counts everyone in those areas as breathing dirty air. Environmental Defense used this counting method to mislead and cry wolf.

The EPA and ED claim for fine particulate matter (PM2.5) is misleadingly high for an additional reason: EPA designated some counties as PM2.5 non-attainment areas not because they exceeded the PM2.5 standard, but because they were believed to contribute to violations elsewhere.

All told, ED overestimates by more than a factor of two the number of people living in areas that violate EPA standards.

Overstated Asthma Danger

Dangerous Days also implies air pollution is responsible for rising asthma rates: “Asthma has increasingly gained attention as a nationwide epidemic and a symbol of the manifold health impacts of air pollution. It is the nation’s fastest growing chronic disease. …” Yet air pollution can’t be a cause of rising asthma, because air pollution of all kinds has been falling nationwide at the same time asthma has been rising.

Air pollution can aggravate pre-existing respiratory disease, but its impact is nothing close to what groups such as ED claim. For example, when the Clinton-era EPA developed the eight-hour ozone standard, it predicted that going from full national attainment of the one-hour standard to full national attainment of the eight-hour standard would reduce hospital admissions for asthma by a mere 0.6 percent, despite the eight-hour standard’s much greater stringency.

Data from around the United States show asthma hospitalizations are lowest in July and August–when levels of ozone and, in many areas PM, are highest.

Cooking the Books

Air pollution has gained the “national attention” referred to by ED not because of its overall importance as a cause of disease and disability, but because of its rhetorical power to generate eye-catching headlines, donations, and research funding.

PIRG’s Danger in the Air makes ED’s Dangerous Days look like a model of reliable analysis. To arrive at its claims about ozone exceedances, PIRG simply adds up the ozone exceedances at each monitoring location in a city or state and calls that the number of exceedances for the area.

Thus, PIRG claims Colorado exceeded the eight-hour ozone standard 60 times in 2003, even though the worst location in the state had 15 exceedances and the average location had fewer than four.

Despite a national average of about four eight-hour ozone exceedances per year in 2003 (see Figure 1), PIRG managed to cook up 4,583 exceedances–a particularly masterful feat when you consider there are only 365 days in a year. PIRG’s method is meaningless for determining health risks or anything else about actual air pollution, but it’s great for generating big, scary numbers.

Mainstream Media Failures

I’ve often criticized the media for their mostly gloomy and misleading accounts of air quality issues. For example, despite the substantial decline in ozone exceedances since the 1970s (see Figure 1), in an April 29, 2004, story on the American Lung Association’s State of the Air 2004 report, the Washington Post asserted, “Ozone pollution has declined slightly over the past 30 years” (emphasis added).

In 2004, however, many reporters around the country noticed the unusually low pollution levels reported by the EPA and let the public know about it. Even here, however, most stories gave the impression that mild weather was the sole cause, and they failed to discuss the long-term decline in smog-forming emissions or to compare smog levels in 2004 with much higher smog levels in previous years that had favorable weather.

Will air pollution remain just as low in 2005? That depends largely on the weather. But emissions will continue to decline, the long-term trend will continue downward … and environmental activists are sure to tell us the sky is falling.

Joel Schwartz ([email protected]) is a visiting fellow at the American Enterprise Institute, a senior fellow with Reason Public Policy Institute, and the author of the AEI report Finding Better Ways to Achieve Cleaner Air.

For more information …

Joel Schwartz’s September 17, 2004 report, Finding Better Ways to Achieve Cleaner Air, is available on the American Enterprise Institute Web site at,pubID.21225/pub_detail.asp.