Air pollution regulations issued by the U.S. Environmental Protection Agency are estimated to save thousands of lives annually. A new study by researchers at Indiana University says these estimates are more uncertain than commonly believed.

Researchers Kerry Krutilla, David H. Good and John D. Graham of the IU School of Public and Environmental Affairs analyzed the costs and expected lifesavings of nine regulations issued between 2011 and 2013. The bulk of these regulations require national emissions standards for hazardous air pollutants. The analysis includes the Mercury and Air Toxic Standards and the Cross State Air Pollution Rule.

The researchers estimate that the lives saved from this group of regulations could plausibly range from none to more than 80,000 per year. The range reflects uncertainty about the health effects of fine particles, and the possibility that airborne exposures to fine particles do not increase mortality risks.

The higher bound for lives saved is comparable to estimates by the EPA, but the possibility that no lives are saved is not reflected in standard EPA analyses of these regulations. If exposures to fine particles do not increase the risk of premature deaths, then most of the regulations in the study are less likely to have economic benefits in excess of their costs.

The IU research is based on a re-evaluation of an EPA-sponsored "expert elicitation" study conducted in 2006. The study surveyed the opinion of experts about the health effects of fine particle exposures. The elicitation format allows experts to synthesize and adjust the empirical findings for limitations in the research area.

Since 2006, the U.S. Environmental Protection Agency has used other methods to assess expert opinion. However, Krutilla, Good and Graham recommend updating the 2006 elicitation study to reflect additional experience with the method and new scientific knowledge. The authors conclude that better information is needed on the economic effects of air regulations, given the wide range for the lives they are estimated to save and the potential impact of the regulations on the U.S. economy.

The study, "Uncertainty in the Cost Effectiveness of Nine Air Quality Regulations," has been published in the Journal of Benefit-Cost Analysis (Spring 2015). Krutilla and Good are associate professors at the School of Public and Environmental Affairs at IU Bloomington; Graham is the school's dean. A team of graduate students assisted the study.