On May 1, the American Lung Association (ALA) will release its annual "State of the Air" report on air pollution levels in American cities. Like previous "State of the Air" reports, the news is alarming. The ALA claims "nearly half of the US population" lives in areas with dangerous levels of air pollution. Metropolitan areas from New York to San Diego are given letter grades of "F" for air quality.
Before taking this year's ALA report at face value, reporters should ask the ALA report's authors a few questions to clarify the report's biases.
1. Is air quality in California, and the U.S. as a whole, better or worse than it was 10 years ago? Five years ago?
Discussion: Air pollution has been declining for decades. While southern California's air pollution remains the highest in the nation, southern California has made more progress than any other region. Figure 1 displays the improving trend in exceedences of the 1-hour ozone standard. National compliance with the 1-hour ozone standard went from about 50% in the early 1980s to 87% today.
About 40% of U.S. monitoring locations still exceed EPA's stringent new 8-hour ozone standard, but 8-hour ozone levels have been dropping as well. Virtually the entire nation (>99%) now meets all federal health standards for carbon monoxide, nitrogen oxides, and sulfur dioxide. More than 96% of the nation complies with PM10 standards (particulate matter under 10 micrometers in diameter), and the compliance rate is about 70% for EPA's stringent new annual PM2.5 standard. PM2.5 declined 33% between 1980 and 2000, with the most polluted areas once again achieving the greatest reductions (see Figure 2 for PM trends).
These declining trends will continue in the coming decade (see discussion of question 4 below).
2. Is every single person in each city or county with an "F" grade exposed to dangerous levels of air pollution?
[If the ALA spokesperson says "Yes" to this question, it will mean they do not know what they are talking about and reporters can stop taking notes. See discussion below.]
Follow up question: For each county, "State of the Air" lists the number of days per year exceeding the 8-hour ozone standard. How many individual monitoring locations in a given county exceeded the ozone standard that many times per year? [The correct answer is zero for almost all counties with more than one ozone monitoring site (see Figure 6 below).]
Discussion: ALA "State of the Air" reports give an entire county an "F" grade if only a single air quality monitor within a county exceeds the EPA's strict new 8-hour ozone benchmark more than 3 times per year. But in most metro areas only a few monitors ever register an exceedence. In some metro areas, only a tiny percentage of the population lives in proximity to air quality monitors that exceed the EPA standard.
For example, ALA gave San Diego an "F" for air quality, claiming that San Diego experienced 16 exceedences per year of the EPA ozone standard. In fact, only a single rural location, Alpine, exceeded the 8-hour ozone standard more than 2 times per year (see Figure 3). 99.7% of people in San Diego County breathe air that meets both the EPA 8-hour and 1-hour ozone standards. ALA greatly exaggerated ozone levels in other metro areas as well (see figures 4, 5, and 6).
This one of the ways in which ALA was able to claim half of all Americans live in areas with unhealthy levels of ozone—they simply included tens of millions of people who actually breathe clean air.
The point: One might argue that talking about the number of days smog is elevated somewhere in a region is not misleading and paints a fair picture of the nature of the regional pollution problem. But the health effects of smog depend on how often a given person is exposed. Since no one is exposed to smog anywhere near as often as the ALA claims, the public is being encouraged to vastly overestimate its risk from air pollution.
3. Does ALA believe that air that exceeds EPA's 8-hour ozone standard poses a major health risk?
Discussion: The EPA's new, stricter 8-hour ozone standard is was selected to offer protection to those people who are considered "most sensitive" to pollution, chiefly the elderly and people with respiratory ailments. Most Americans do not face significant risk from current levels of ozone. For example, the EPA projects that going from nationwide attainment of the 1-hour ozone standard to attainment of the 8-hour standard would reduce emergency room visits for asthma by 0.6 percent, even though the 8-hour standard is significantly more stringent. Comparison of air pollution levels in California counties shows that there is little relationship between air pollution levels and asthma prevalence (see Figure 7), while a recent study of California's Central Valley, funded by the California Air Resources Board, found that emergency room visits and hospitalizations for respiratory disease were lower on days with higher ozone. While no one believes ozone protects against respiratory harm, the effects of ozone at current levels are small enough that epidemiologists have difficulty detecting any change in health outcomes with changes in air pollution levels. Nevertheless, ALA claims 40% of Americans are "at risk" when air pollution exceeds the 8-hour ozone benchmark on just a few days per year.
Discussion: ALA claims in the "State of the Air" that "the improvement in ozone levels seen in 1999-2001 is likely due to favorable weather conditions rather than significant new measures to reduce pollution," and "much air pollution cleanup has been stalled during the past five years, because the U.S. Environmental Protection Agency has failed to take steps to enforce more the more protective ozone standard adopted in 1997." (p. 3, col. 1).
In fact, the downward trend in pollution levels has been ongoing and will continue. On-road pollution measurements show emissions from gasoline vehicles are dropping by about 10 percent per year, as the fleet turns over to more recent models that start out and stay much cleaner than vehicles built years ago. Diesel truck emissions are also declining, albeit about half as fast. Although motorists are driving more miles each year and population growth means more motorists on the roads, these increases in driving are tiny compared to the large declines in vehicle emission rates and will do little to slow progress on auto pollution (see Figure 8).
Emissions from industrial sources will also continue to drop. Starting in 2004, EPA regulations require a 60 percent reduction in summertime NOx emissions from coal-fired power plants and industrial boilers—the major industrial sources of ozone-forming pollution, and a 20 percent reduction in PM-forming SO2 from power plants between now and 2010. These reductions are in addition to substantial declines in industrial NOx and SO2 emissions during the last 30 years.
Clearly "State of the Air" is designed to generate alarming headlines—and aid fundraising for the American Lung Association—rather than provide the media and the public with accurate information on air pollution. Last August Andrew Goldstein of Time magazine wrote: "Fuzzy math and scare tactics might help green groups raise money, but when they, abetted by an environmentally friendly media, overplay their hand, it invites scathing critiques. . ." (From "Too Green for Their Own Good?" Time magazine, August 26, 2002.)
Joel Schwartz is an adjunct fellow at Reason Foundation and visiting scholar at American Enterprise Institute.
Steven F. Hayward is senior fellow in environmental studies at the Pacific Research Institute, and a resident scholar at the American Enterprise Institute.