One of the all-too-many shibboleths of the anti-suburbanites is that the rise in automobile air pollution has produced a rise in asthma cases. There is, of course, only one problem with this view --- that for 35 years, air pollution has been dropping in the urban areas of the United States and Western Europe. Thus, if there is a connection between the two trends, it has to be that less air pollution causes more asthma. Of course that is not true, but any attempt to blame automobile produced air pollution for the increase in asthma flies in the face of reason.
This specious claim of the anti-suburbanites has made me sensitive to the issue. So, it was with great interest that I read the new “Asthma Capitals” report of the Asthma and Allergy Foundation of America (AAFA). This report provides a ranking of 100 United States metropolitan areas using an index of 12 factors. It is a very strange index, combining estimates of the incidence of asthma and “risk factors,” such as school inhaler access laws and poverty rates. It might be argued that these “risk factors” (9 of the 12 factors) contribute to the incidence of asthma, but there is no better measure of the prevalence towards asthma than the actual cases. Only three of the Asthma Capital criteria deal with that.
It would seem that the risk factors should predict the comparative number of incidents. They do not and by a long shot. If, for example, a score of 1 to 3 is given for each of the three incident categories rates, the worst score would be 9 (the rating is simply, worse than average, average and better than average) and the best score would be 0. The results are considerably different than the more complex index system that includes the risk factors
Looking at the list, Atlanta, considered the worst (#1) by AAFA would have a score of 7, not much worse than best (#100) Seattle, which has a score of 6. Perennial urban planning favorite, Portland, ranked in the top quarter by AAFA (#75) actually gets the worst score possible, at 9, along with a number of other areas, along with the urban elite favorites of New York, Boston and Washington. Colorado Springs is rated #95 (6th best) by AAFA, yet would also have the worst possible score in asthma incident factors, at 9, tied with Portland.
So what do the Asthma Capitals ratings tell us? Not much of anything. The best way to compare the relative risk of asthma between metropolitan areas is to identify the percentage of people who have asthma. The Asthma Capitals ratings have a potential to be misleading, given that simply are not an evaluation of the actual asthma rates in urban areas, yet have been interpreted by some in the press to be that. The problem is that the Asthma Capital ratings are largely based upon predictive factors that don’t predict very well at all.