On May 1 the American Lung Association (ALA) released its State of the Air 2001 report.1 Despite the sweeping nature of its title, the purpose of ALA’s report was to examine the levels of one pollutant, ground-level ozone, for all U.S. counties that had ozone-monitoring stations located within their boarders. The study was particularly harsh on North Carolina. It ranked three of the state’s counties Mecklenburg, Wake, and Rowan in its top 25 “most ozone-polluted counties in the nation” (11th, 16th and 19th respectively2) and gave a grade of F to 24 out of 29 monitored counties in the state.3
After close examination it is clear that the ALA study is at best misleading and should not be used as either an indicator of current levels of ozone pollution or the actual health effects of ozone on North Carolina citizens. In addition, the ALA’s grading system says nothing about health effects and misleads the reader with respect to the number of people affected by concentrations of ozone.
The Hazards and Benefits of Ozone
Ozone is a colorless and odorless gas that is not emitted directly into the air but is the product of mixing together two other gasses. In particular, ozone forms on hot, sunny days when nitrogen oxides, in part a by-product of running cars and generating electric power, react with hydrocarbons in the air. All ground-level ozone is not human-produced. There is a natural background level of ozone, which also is higher on hot sunny days. In part this natural background level is associated with tree growth and heavy forestation which puts North Carolina at a higher starting point for ozone than many other states. Insects also generate natural ozone. Regardless of its source, ozone has both negative and positive health effects. On the negative side, it is an aggravating factor for people with respiratory problems such as asthma, bronchitis, and emphysema. But ozone also has positive health effects, which some researchers have argued more than offset its negative effects on the respiratory system.4
Ozone is a natural screen, which helps protect people from harmful ultraviolet rays of the sun, reducing the incidence of skin cancer. While, as documented by the ALA, a positive relationship has been shown to exist between higher concentrations of ozone and aggravated respiratory problems, it is also the case that both the U.S. Department of Energy and the EPA have shown that higher concentrations of ozone are associated with fewer incidences of several different forms of skin cancer.5 As noted by the highly respected and independent environmental think tank Resources for the Future, “Ground level, like stratospheric ozone, has been linked with reductions in exposures to UV-B, which causes skin cancer. These health effectsare no less uncertain than some of the [negative] health effects” 6These benefits of ozone are not noted anywhere in the ALA report. In fact, no where in the ALA report is it indicated that ozone is anything but harmful.
ALA Data and Grading System
The ALA report examines what are called “ozone exceedance” days on a county by county basis for years 1997 through 1999. An “exceedance day” for an entire county is registered whenever any one monitor in the county registers .085 ppm (parts per million) averaged over an eight-hour period. This is a new and very controversial standard that was imposed by the Clinton Administration in 1998 over the objections of a majority of the EPA’s own Clean Air Scientific Advisory Committee (CASAC). It should be noted that then-Gov. Jim Hunt immediately adopted the standard for North Carolina even though implementation by the federal government was held-up in the courts until very recently.
The ALA gave a grade of F to any county that had an average of at least 3.3 exceedance days per year during the three-year period. Most of the larger counties have several monitors located in different locations. An exceedance measured on any one monitor was counted against the entire county. The ALA used a weighting system where a low-level exceedance, known as a code orange, was counted as 1 exceedance day while higher level exceedances, code red and code purple, were effectively counted as more than one day.7 This methodology combined with the years chosen to evaluate has created a distinctly false impression concerning ozone levels in N.C.
The ALA’s Misleading Ozone Data8
The most significant fact concerning the ALA study is that the years 1997, 1998, and 1999 were anomalies. They are not necessarily reflective of ozone levels that North Carolinians should expect to experience in the future. As noted by North Carolina’s Department of Environment and Natural Resources (DENR), “[t]he weather in North Carolina was very conducive to ozone formation during the summers of 1998 and 1999, which were unusually hot, dry, and stagnantFrom 1997-1999, more than two-thirds of the state’s ozone monitoring sites exceeded the new standards” [at some point during the period].9 It is likely the case that this unusual weather was caused by the El Nino that was driving weather patterns throughout the United States during this time period.
Table I shows annual ozone exceedance days for the entire state of North Carolina from 1994 to 2000. It is clear that for the state as a whole 1997, 1998, and 1999 were anomalies. During 2000 North Carolina had half the number of exceedance days as it did in 1999. Table II examines the average number of exceedances recorded at all of the monitors in Mecklenburg, Wake, and Rowan by three-year periods from 1991-1999 and in 2000. (Data for Rowan County were not available for 1991-1993.) There are four in Wake, three in Mecklenburg, and two in Rowan. It is quite clear that 1997-99 the time period reported on by the ALA is not typical of North Carolina ozone levels and was obviously a very bad predictor of ozone levels to come in the following year (2000).
Abstracting from the 1997-1999 period, there seems to be no detectable upward trend in ozone exceedances for the entire decade of the 1990s. This is in spite of the fact that the state and the counties in question have experienced significant economic growth during this time period. More electric power is being consumed and more cars are on the road. The fact is that recent compliance problems in North Carolina seem to have little to do with actual increases in ozone levels and can be attributed to the change in standards by the Clinton and Hunt Administrations. According to NC’s DENR, “The entire state had been in compliance with the old ozone standard since the early 1990s”10
Also leading to false conclusions is the report’s policy of declaring entire counties out of compliance with ozone standards so long as there is at least one monitor showing an exceedance. Wake County, for example, has four ozone monitoring sites, at Fuquay-Varina, Milbrook Road, St. Augustine’s College, and the WRAL Tower. If only one of these monitors shows an exceedance then the entire county is counted as being out of compliance and therefore the “at risk” population of the entire county is listed by the ALA as being harmed. For example, in 1998 Fuquay registered 24 exceedances, the highest number in the county. This was four more than the next highest, which was recorded by the Milbrook monitors. This means that there were at least four days during that year where the only exceedances that were recorded were in the relatively rural community of Fuquay. Yet the ALA counted all of Wake as being out of compliance and the entire at-risk population of Raleigh, about 15 miles away, was listed as being exposed to unhealthy air. In 1999 the exact opposite problem occurred. Fuquay registered only 8 exceedances while the three Raleigh locations had readings that showed exceedances 22 to 26 times.
Finally, the methodlogy is biased against counties with more than one monitor. Each additional monitor increases the chance that any one will show an exceedance day. North Carolina has the second-largest number of monitors in the Southeast, suggesting that, using this methodology, it will inevitably appear worse than similar states with the same air but fewer monitors. In sum, the ALA has incorrectly identified many clean air locations as being out of compliance and has illegitimately scared many people into thinking that they have been breathing “unhealthy air” when they have not.
ALA’s Grading System
The ALA’s A to F grading system is so misleading as to be nearly useless in conveying any information regarding either the extent of the health related problems that might be due to ozone levels or relative air quality on a county by county basis. To reiterate, a county is given a grade of F if there were an average of 3.3 monitor readings a year greater than or equal to .085 ppm averaged over an eight-hour period. In fact, if the readings were in the code red or code purple range, fewer than three readings a year could give the county a grade of F. This raises several problems. Imagine county A and county B where county A registers 10 mild exceedance days of .085 ppm over a three-year period, with no other days registering above .07 ppm. This county would be given an “F” by the ALA. Now imagine county B where there are 40 days measuring .084 ppm with no day registering below .08 ppm. The ALA grading system would give county B a grade of “A” because it had no exceedances over the three year period. It is quite clear that these two grades would tell us nothing about the relative healthiness of the air in these two counties.
When carefully scrutinized, the rhetoric in the ALA study concerning what the implied health effect might be of getting one grade or another in their rating system actually has very little substantive merit. In reviewing the health implications of the .085 ppm standard compared to other less stringent standards that were being considered the EPA’s CASAC concluded that “there is no bright line that distinguishes any of the proposed standards (either the level or the number of allowable exceedances) as being significantly more protective of public health.”11 Yet the ALA writes as if such a bright line exists at .085 ppm. Throughout the section of the study titled “Health Effects of Ozone” references are made to the consequences of exposure to “high” and “low” levels of ozone but in fact it gives no specific data concerning health effects that will occur when the .085 ppm threshold is crossed.12 For example the ALA states that “More than 30 million children under the age of 14 whose lungs are particularly vulnerable to the effects of ozone-filled air are living in counties that received an “F” in air quality.”13
Given the problems with the ALA grading system and the view of the CAPAC scientists that reviewed the EPA standard, it should be clear that such statements create a great deal of heat but shed no light on the actual health effects of an ALA grade of F. These kinds of statements only serve to create unwarranted fear in the minds of parents. Since the ALA has primarily become an environmental advocacy group, similar to Environmental Defense or the Sierra Club, the likely purpose behind these kinds of statement is to encourage people to mobilize behind legislation and to stimulate contributions, not to provide objective science or enlighten the public. This is evidenced by the fact that on nearly every page of the report posted on the ALA web site the group encourages people to sign its petition to President George W. Bush calling for stronger pollution controls on trucks, SUVs, and power plants. In the petition the only evidence the ALA cites in support of its plea relates to the grades that were received by counties in their report.
While one would never know it from reading “The State of the Air 2001” report, overall air quality in North Carolina has shown steady improvement for the last three decades. As reported by the DENR, “levels of particulates, carbon monoxide, sulfur dioxide and lead have dropped substantially in the ambient air since the 1970s.”14 The ALA reported none of this because in fact their study did not look truly at “the state of the air” but only at one pollutant, ozone, for one three-year period that ended a year and a half ago. It is clear that this study had much more to do with advocacy than science and that it could never have passed scientific peer review or have been accepted in a legitimate scientific journal.
Unfortunately, North Carolina’s media, apparently hungry to report bad news about our state’s environment, made no effort to investigate the legitimacy of the report’s claims or the methodology used to arrive at its conclusions.15 Let’s hope that their attention to the details will be different next year when the ALA comes out with it’s “State of the Air 2002.” Since this report will cover the years 1998-2000 and will therefore once again include the abnormal years of 1998 and 1999, we can expect that next year’s report will be just as “scientifically sound” as this year’s report.
Dr. Roy Cordato, Vice President and Resident Scholar
- Found at www.lungusa.org.
- Found at www.lungusa.org/air2001/table4.html.
- Found at www.lungusa.org/air2001/states/s_nc.html.
- See Susan E. Dudley, “Comments on the U.S. EPA’s Proposed National Ambient air Quality Standard for Ozone, published by George Mason University’s Center for the Study of Public Choice Regulatory Analysis Program, pp. B-1-B4, March 12, 1997.
- Dr. Alan J. Krupnick, “The Proposed National Ambient Air Quality Standards (NAAQS) for Particulate Matter (PM) and Ozone,” prepared remarks delivered to the U.S. Senate subcommittee on Clean Air, Wetlands, Private Property and Nuclear Safety, Committee on Environment and Public Works, April 24, 1997. Found at www.rff.org/testimony/remarks/naaqs1.htm.
- For a description of ALA’s methodology see www.lungusa.org/air2001/description.html.
- Unless otherwise noted, all data presented in this section was provided by the North Carolina Department of Environment and Natural Resources, Division of Air Quality.
- “2000 North Carolina State of the Environment Report” chapter 2 “Air Quality“, p. 19.
- Ibid. p. 17.
- As quoted in Dudley, op. cit. at note 2, p. II-1.
- Found at www.lungusa.org/air2001/ozone.html#elderly.
- Found at www.lungusa.org/air2001/intro.html#executive.
- Op.cit, note 9, p. 17. 15 It should be noted that the media reacted similarly earlier this year to an equally junk science riddled report on the effects of global warming in North Carolina that was published by the left wing advocacy group, Physicians for Social Responsibility. Few if any news reports noted that the study was not written by Physicians, that the leaders of the organization are not MDs, or that being an MD is not a requirement for membership.