Air pollution and human health: a review and reanalysis.
Since 1970, Lave and Seskin have published a series of articles dealing with the question, "Does air pollution shorten lives?" Their recent book reports revised and extended analyses of their previous studies emphasizing policy implications. We have undertaken a review of Lave and Seskin's book to evaluate the methodology used and hence gain some insight into the strength of the conclusions reached. This review concentrates on methodology and its application to establishing and quantifying the association between air quality and health. Beyond simply reviewing the analyses reported in Lave and Seskin's book, we have duplicated and expanded two of the reported analyses. Our detailed reanalysis is presented both to verify reported results, and to illustrate the difficulties encountered in such an analysis. Our overall conclusion is that Lave and Seskin have done a thorouth job of reporting and interpreting the various analyses that they performed. Lave and Seskin have made a pioneering effort in showing an association between mortality rates and air pollution. We do not disagree with the conclusion of the existence of an association but have some reservations about their methods of estimating its magnitude. We were particularly concerned that Lave and Seskin did not fully investigate how well their models fit these data. Our reanalysis results in estimated effects which differ considerably from the values reported by Lave and Seskin. Thus, we conclude that the regression coefficients are quite unstable and so must be used with care. Assessing the relative costs and benefits of reducing air pollution without extensive sensitivity analysis could, therefore, be misleading.