The myth, based on 17 special days of reduced traffic, lower air pollution and fewer asthma cases, isolated and studied for some unique meaning, like so many myths, was more fancy than fact.
By Harold Brown
The Summer Olympics came to Atlanta in July and August 1996, and some people are still talking about it, as I observed at a recent forum. Nothing about the events’ winners and losers, of course, but about the environmental ramifications.
Cars stayed away from downtown in droves. Ridership on public transportation was reported up 250 percent. The media hailed the experiment in reducing traffic, pollution and asthma. Even the Department of Natural Resources’ Environmental Protection Division saw it as a successful, if brief, solution to Atlanta’s air pollution problem: The agency still has a separate Web page devoted to ozone readings during the Games.
While the EPD seems to offer half-hearted support, it and the federal Environmental Protection Agency have referred to the Atlanta example in several subsequent publications. And so an urban myth has grown and continues to be passed on, in spite of warnings that ignorance and uncertainty about its foundation made it more ghost than genuine.
Seventeen days (July 19-Aug. 4, 1996) is fleeting when compared to the years involved in most attempts to associate air pollution and asthma. Atlanta doctors, however, reported in the Journal of the American Medical Association that daily cases of asthma were about 40 percent fewer and average the ozone level was 22.7 parts per billion lower during the Olympics than during the four weeks before and after. Others, who analyzed the whole period from 1993 to 1999, have reported only about one-tenth as much decrease in asthma in Atlanta during similar decreases in ozone. Authors of the 2001 JAMA article speculated that the decreased ozone was due to less vehicle traffic during the Games.
Conclusions about connections between traffic, ozone and asthma are influenced by the days chosen for comparison and, of course, by weather on those days. The State Implementation Plan for the Atlanta Ozone Non-attainment Area (DNR, 2001) illustrated the effect of the Olympics by showing July 18 when ozone peaked at 62 ppb (at the Confederate Avenue site) compared to 129 ppb on July 10. So did the Atlanta Journal (1997). But the comparison would have been reversed if July 12 (65 ppb) and July 24 (101 ppb) had been chosen.
In a more complete analysis DNR focused (appendix XIV to the Implementation Plan) on the period from July 15-23, including four days before the Games started. Would ozone anticipate the Games? They focused, in particular, on “four days during this period (July 17-20) which appeared to have meteorological conditions conducive to formation of ozone levels greater than that actually observed.” They compared these four “good days” which straddled the beginning of the Olympics, with June 30, a day of high ozone. The DNR concludes, non-committally, “it would seem reasonable to expect ozone levels greater than that observed during the Olympic and pre-Olympic period.” So they didn’t conclude that ozone was lower during the Olympics, but that it was lower than expected based on weather. It is unlikely that asthma is influenced by the designation “lower than expected.”
In fact, ozone did not decrease during the Olympics compared to the week before (July 12-18); the average of maximum daily levels was the same (58 ppb average of levels at Decatur, Tucker and Confederate Avenue). And average ozone was only 10 percent higher during the following 10 days. How far on either side could the Games have an effect on ozone?
Obviously, there must be something special about the Olympics that makes the myth so appealing. Perhaps it was the relief that massive increases in traffic expected during the Olympics didn’t occur. Perhaps the perception that reduced traffic temporarily solved air pollution helped spawn the myth; a readymade experiment free for the analysis. Yet the myth, based on 17 special days of reduced traffic, lower air pollution and fewer asthma cases, isolated and studied for some unique meaning, like so many myths, was more fancy than fact.
Even the basic premise fails. It was known in the fall of 1996 that traffic was not reduced. The conclusion of DNR was; “Data from DOT indicates that the actual total daily amount of traffic reduction was not that significant.” Some feared an increase in traffic and air pollution, but as David Goldberg wrote for the Atlanta Constitution on Oct. 11, 1996, “ … the surprise was that traffic levels during the Olympics were similar to those before the Games.”
Although the JAMA paper lists traffic reduction during weekday one-hour morning peaks as 22.5 percent, it says weekday 24-hour total traffic was down only 2.8 percent. In the highly variable patterns of ozone and asthma, 2.8 percent less traffic for a few days would cause hardly a blip. If 2.8 percent less traffic could reduce asthma cases 40 percent or more, as reported in the JAMA article, 7 percent less would wipe out them out altogether.
The DNR was not very committal about the connection between traffic and ozone. Its State Implementation Plan said of changes during the Olympics: “The effect of these transportation alternatives, used by the permanent and temporary population, on air quality is uncertain.
But that was a long time ago. Why expose an 8-year-old myth? It may be that criticism will only help sustain it. It may otherwise fade on its own; perhaps it already has. Perhaps nobody cares if the facts and associations are shaky as long as it’s a selling point for clean air.
No; all myths based on such hearsay deserve a burial, not a resurrection at every clean-air rally. Its resurrection at a forum on air quality in Atlanta in June and in a JAMA editorial last year shows that its spirit lives, though its corpus never did.
University of Georgia Professor Emeritus Harold Brown is an Adjunct Scholar with the Georgia Public Policy Foundation and author of “The Greening of Georgia: The Improvement of the Environment in the Twentieth Century.” The Georgia Public Policy Foundation is an independent think tank that proposes practical, market-oriented approaches to public policy to improve the lives of Georgians. Nothing written here is to be construed as necessarily reflecting the views of the Georgia Public Policy Foundation or as an attempt to aid or hinder the passage of any bill before the U.S. Congress or the Georgia Legislature.
© Georgia Public Policy Foundation (July 16, 2004). Permission to reprint in whole or in part is hereby granted, provided the author and his affiliations are cited.
By Harold Brown
The Summer Olympics came to Atlanta in July and August 1996, and some people are still talking about it, as I observed at a recent forum. Nothing about the events’ winners and losers, of course, but about the environmental ramifications.
Cars stayed away from downtown in droves. Ridership on public transportation was reported up 250 percent. The media hailed the experiment in reducing traffic, pollution and asthma. Even the Department of Natural Resources’ Environmental Protection Division saw it as a successful, if brief, solution to Atlanta’s air pollution problem: The agency still has a separate Web page devoted to ozone readings during the Games.
While the EPD seems to offer half-hearted support, it and the federal Environmental Protection Agency have referred to the Atlanta example in several subsequent publications. And so an urban myth has grown and continues to be passed on, in spite of warnings that ignorance and uncertainty about its foundation made it more ghost than genuine.
Seventeen days (July 19-Aug. 4, 1996) is fleeting when compared to the years involved in most attempts to associate air pollution and asthma. Atlanta doctors, however, reported in the Journal of the American Medical Association that daily cases of asthma were about 40 percent fewer and average the ozone level was 22.7 parts per billion lower during the Olympics than during the four weeks before and after. Others, who analyzed the whole period from 1993 to 1999, have reported only about one-tenth as much decrease in asthma in Atlanta during similar decreases in ozone. Authors of the 2001 JAMA article speculated that the decreased ozone was due to less vehicle traffic during the Games.
Conclusions about connections between traffic, ozone and asthma are influenced by the days chosen for comparison and, of course, by weather on those days. The State Implementation Plan for the Atlanta Ozone Non-attainment Area (DNR, 2001) illustrated the effect of the Olympics by showing July 18 when ozone peaked at 62 ppb (at the Confederate Avenue site) compared to 129 ppb on July 10. So did the Atlanta Journal (1997). But the comparison would have been reversed if July 12 (65 ppb) and July 24 (101 ppb) had been chosen.
In a more complete analysis DNR focused (appendix XIV to the Implementation Plan) on the period from July 15-23, including four days before the Games started. Would ozone anticipate the Games? They focused, in particular, on “four days during this period (July 17-20) which appeared to have meteorological conditions conducive to formation of ozone levels greater than that actually observed.” They compared these four “good days” which straddled the beginning of the Olympics, with June 30, a day of high ozone. The DNR concludes, non-committally, “it would seem reasonable to expect ozone levels greater than that observed during the Olympic and pre-Olympic period.” So they didn’t conclude that ozone was lower during the Olympics, but that it was lower than expected based on weather. It is unlikely that asthma is influenced by the designation “lower than expected.”
In fact, ozone did not decrease during the Olympics compared to the week before (July 12-18); the average of maximum daily levels was the same (58 ppb average of levels at Decatur, Tucker and Confederate Avenue). And average ozone was only 10 percent higher during the following 10 days. How far on either side could the Games have an effect on ozone?
Obviously, there must be something special about the Olympics that makes the myth so appealing. Perhaps it was the relief that massive increases in traffic expected during the Olympics didn’t occur. Perhaps the perception that reduced traffic temporarily solved air pollution helped spawn the myth; a readymade experiment free for the analysis. Yet the myth, based on 17 special days of reduced traffic, lower air pollution and fewer asthma cases, isolated and studied for some unique meaning, like so many myths, was more fancy than fact.
Even the basic premise fails. It was known in the fall of 1996 that traffic was not reduced. The conclusion of DNR was; “Data from DOT indicates that the actual total daily amount of traffic reduction was not that significant.” Some feared an increase in traffic and air pollution, but as David Goldberg wrote for the Atlanta Constitution on Oct. 11, 1996, “ … the surprise was that traffic levels during the Olympics were similar to those before the Games.”
Although the JAMA paper lists traffic reduction during weekday one-hour morning peaks as 22.5 percent, it says weekday 24-hour total traffic was down only 2.8 percent. In the highly variable patterns of ozone and asthma, 2.8 percent less traffic for a few days would cause hardly a blip. If 2.8 percent less traffic could reduce asthma cases 40 percent or more, as reported in the JAMA article, 7 percent less would wipe out them out altogether.
The DNR was not very committal about the connection between traffic and ozone. Its State Implementation Plan said of changes during the Olympics: “The effect of these transportation alternatives, used by the permanent and temporary population, on air quality is uncertain.
But that was a long time ago. Why expose an 8-year-old myth? It may be that criticism will only help sustain it. It may otherwise fade on its own; perhaps it already has. Perhaps nobody cares if the facts and associations are shaky as long as it’s a selling point for clean air.
No; all myths based on such hearsay deserve a burial, not a resurrection at every clean-air rally. Its resurrection at a forum on air quality in Atlanta in June and in a JAMA editorial last year shows that its spirit lives, though its corpus never did.
University of Georgia Professor Emeritus Harold Brown is an Adjunct Scholar with the Georgia Public Policy Foundation and author of “The Greening of Georgia: The Improvement of the Environment in the Twentieth Century.” The Georgia Public Policy Foundation is an independent think tank that proposes practical, market-oriented approaches to public policy to improve the lives of Georgians. Nothing written here is to be construed as necessarily reflecting the views of the Georgia Public Policy Foundation or as an attempt to aid or hinder the passage of any bill before the U.S. Congress or the Georgia Legislature.
© Georgia Public Policy Foundation (July 16, 2004). Permission to reprint in whole or in part is hereby granted, provided the author and his affiliations are cited.