Research Feasibility of Assessing Public Health Impacts of Air Pollution Reduction Programs on a Local Scale: New Haven Case Study Danelle T. Lobdell,1 Vlad Isakov,2 Lisa Baxter,2 Jawad S. Touma,2 Mary Beth Smuts,3 and Halûk Özkaynak 2 1U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Chapel Hill, North Carolina, USA; 2U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory, Research Triangle Park, North Carolina, USA; 3U.S. Environmental Protection Agency, Region 1, Boston, Massachusetts, USA Background : New approaches to link health surveillance data with environmental and population exposure information are needed to examine the health benefits of risk management decisions. o Bjectiv : We examined the feasibility of conducting a local assessment of the public health impacts of cumulative air pollution reduction activities from federal, state, local, and voluntary actions in the City of New Haven, Connecticut (USA). Methods : Using a hybrid modeling approach that combines regional and local-scale air quality data, we estimated ambient concentrations for multiple air pollutants [e.g., PM2.5 (particulate mat- ter ≤ 2.5 mμ in aerodynamic diameter) , NOx (nitrogen oxides)] for baseline year 2001 and projected emissions for 2010, 2020, and 2030. We assessed the feasibility of detecting health improvements in relation to reductions in air pollution for 26 different pollutant–health outcome linkages using both sample size and exploratory epidemiological simulations to further inform decision-making needs. r esult : Model projections suggested decreases (~ 10–60%) in pollutant concentrations, mainly attributable to decreases in pollutants from local sources between 2001 and 2010. Models indi- cated considerable spatial variability in the concentrations of most pollutants. Sample size analyses supported the feasibility of identifying linkages between reductions in NOx and improvements in all-cause mortality, prevalence of asthma in children and adults, and cardiovascular and respiratory hospitalizations. c onclusi : Substantial reductions in air pollution (e.g., ~ 60% for NOx) are needed to detect health impacts of environmental actions using traditional epidemiological study designs in small communities like New Haven. In contrast, exploratory epidemiological simulations suggest that it may be possible to demonstrate the health impacts of PM reductions by predicting intraurban pol- lution gradients within New Haven using coupled models. k ey words : air pollution, feasibility analysis, health effects, nitrogen oxides, particulate matter. Environ Health Perspect 119:487–493 (2011). doi:10.1289/ehp.1002636 [Online 18 February 2011] Assessing the overall impact of cumulative air pollution programs on environmental pub- lic health is a daunting task. Air quality has improved substantially in the United States in recent decades, in large part because of increas- ingly stringent federal and state air quality regulations. Although many studies have documented links between better air qual- ity and improvements in a variety of human health metrics (Clancy et al. 2002; Friedman et al. 2001; Hedley et al. 2002; Heinrich et al. 2002; Pope 1989; Pope et al. 2009), direct evidence concerning the extent to which spe- cific control measures have improved health is lacking. This lack of evidence is due in part to inherent difficulties in environmental health research concerning effects of relatively low- level exposures on multifactorial health out- comes with long latency periods that often are associated with small changes in relative risk (RR). In addition, complex interactions between interventions over time make it diffi- cult to isolate the environmental health effects of any one regulation. No single study or study design is likely to characterize the entire range of public health improvements attributable to an air quality regulation (Health Effects Institute 2003). Although the study of the impact of cumula- tive air pollution control programs on environ- mental public health is fairly unique compared with those involving individual programs, and formal research approaches are still in early phases of development, several recently published research studies have contributed relevant insights by taking advantage of epi- sodic, one-time events or natural experiments such as a coal ban (Clancy et al. 2002), traffic reductions (Friedman et al. 2001; Tonne et al. 2008), and closure of a steel mill (Parker et al. 2008; Pope 1989). Burnett et al. (2005) pro- posed a “measure of progress” equivalent to the percent reduction in the RR of adverse health outcomes attributable to reductions in ambient air pollutant concentrations. They note that their proposed approach is applicable to single and multiple cities, as well as single and mul- tiple pollutants. However, they demonstrate their approach only with time-series data on mortality associated with ambient nitrogen dioxide (NO2) concentrations from 1981 to 1999 in multiple Canadian cities. Jerrett et al. Environmental Health Perspectives • volume 119 | number 4 | April 2011 (2007) pointed out that evidence of short- term health improvements based on studies of “natural experiments” and well-delineated interventions may not apply directly to effects of gradual air quality improvements over many years, and when the follow-up period is long, many other factors, such as random error and systematic biases, especially for low RRs (< 1.05), can obfuscate the linkage of air qual- ity improvements to health benefits. Thus, it is important to determine a priori which pol- lutant–outcome relationships are most likely to result in observable impacts on health in a particular population given projected changes in air pollutant concentrations and estimated risks associated with exposures of concern. Of course, even when benefits are not statistically detectable based on observational data, it is helpful to decision makers to know the cir- cumstances in which health benefits of pollu- tion reductions are expected to occur. This challenge was recently addressed by Pope et al. (2009) for ambient particulate matter (PM). They used an ecological ana- lytic approach whereby they examined associa- tions between noticeable changes in ambient PM levels and differences in life expectancy estimates [~ 0.61 years per 10-gμ/m 3 decrease in PM ≤ 2.5 μm in aerodynamic diameter (PM2.5)] across multiple metropolitan areas in the United States between 1980 and 2000 using multiple regression models adjusted for socioeconomic status, demographic character- istics, and smoking. The models were similar in structure to those previously used in a cross- sectional analysis of air pollution effects on mortality by Özkaynak and Thurston (1987). Address correspondence to H. Özkaynak, U.S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory (E205-01), Research Triangle Park, NC 27711 USA. Telephone: (919) 541-5172. Fax: (919) 541-0239. E-mail: ozkaynak.haluk@epa.gov We are grateful to J. Xue, S. Darney, and A. Geller with the U.S. Environmental Protection Agency (EPA), Office of Research and Development for their input and comments on the manuscript. The U.S. EPA through its Office of Research and Development partially funded the research described here under contract EP-D-07-109 with Westat, Inc., and contract GS-35F-4381G to CSC, Inc. It has been subjected to agency review and approved for publication. The authors declare they have no actual or potential competing financial interests. Received 28 June 2010; accepted 18 February 2011. 487