Liu et al. Interactions between proximity of residence to fuel-fired power plants and waste sites. We found a significant elevation in rates of hospital- ization for respiratory diseases among individu- als > 10 years of age who lived near a fuel-fired power plant after adjusting for age, sex, race/ ethnicity, MHI, and urban/rural residence. We confirmed that living near waste sites was asso- ciated with significantly increased rates of hos- pitalization for asthma, ARI, and COPD. The results of the present study show that hospitalization rates in individuals living in ZIP codes with both a fuel-fired power plant and a hazardous waste site are increased com- pared with rates associated with exposure to either factor alone, and the RRs are approxi- mately additive. This indicates how impor- tant it is in a study such as this to control for both types of exposure. Although asthma and ARI hospitalizations in children < 10 years of age did not show significant associations with residence near fuel-fired power plant sites, residence near both a fuel-fired power plant and a hazardous waste site was associated with higher rates of hospitalization than residence near a waste site alone. Limitation or bias. There are several methodical limitations in this study. Residence in a ZIP code containing a fuel-fired power plant or a waste site was our only measure of exposure. Because fuel-fired power plants usu- ally have high stacks, the contaminants may migrate beyond the geographic area covered by a ZIP code. Thus, residents in a “clean” ZIP code could be exposed if they are downwind of a fuel-fired power plant (Pala et al. 2010). We do not have information on the height of the stacks of individual power plants or their location within ZIP codes, and we did not control for wind direction or strength. We did not have data available to control for potential confounders such as genetic predisposition, smoking, diet, and other personal habits. We monitored only hospitalizations and did not have information about emergency depart- ment or physician office visits. We also cannot distinguish multiple hospitalizations for one individual from those for several individuals, and we did not have information on residence locations at times other than at hospitalization. New York State residents who sought out- of-state health care were not included in this data set, nor were patients admitted to feder- ally regulated hospitals. SES is a particularly important confounder that was only partially controlled for in our study through the use of MHI for each ZIP code. Strengths of the study. There are, however, major strengths of this study. We had data on a very large population over a long period of time and could control for age, sex, race/eth- nicity, urban/rural residence, and ZIP-code- level MHI as a surrogate for SES. In spite of the limitations, most of which would tend to obscure risk relationships, we found a sig- nificant elevation in rates of hospitalization for asthma, ARI, and COPD among individuals living in ZIP codes containing fuel-fired power plants and confirmed our previous findings that residence near hazardous waste sites is also associated with increased hospitalization rates for the outcomes examined. Moreover, our results are consistent with those of other investigations relating respiratory disease hospitalization to exposure to air pollutants (O’Connor and Roy 2008; Pala et al. 2010). Although semiecologic studies such as ours must always be considered to be hypoth- esis generating, the congruence between these results and previous information provides addi- tional evidence that use of the large SPARCS data set has value in identifying patterns of disease in relation to residential exposures. Ref Rencs Atkinson RW, Anderson HR, Sunyer J, Ayres J, Baccini M, Vonk JM, et al. 2001. Acute effects of particulate air pol- lution on respiratory admissions: results from APHEA 2 project. Air Pollution and Health: A European Approach. Am J Respir Crit Care Med 164:1860–1866. Carpenter DO, Ma J, Lessner L. 2008. Asthma and infectious respiratory disease in relation to residence near hazard- ous waste sites. Ann NY Acad Sci 1140:201–208. Carpenter DO, Shen Y, Nguyen T, Le L, Lininger LL. 2001. Incidence of endocrine disease among residents of New York areas of concern. Environ Health Perspect 109(suppl 6):845–851. Chauhan AJ, Johnston SL. 2003. Air pollution and infection in respiratory illness. Br Med Bull 68:95–112. Dales RE, Cakmak S, Doiron MS. 2006. Gaseous air pollutants and hospitalization for respiratory disease in the neonatal period. Environ Health Perspect 114:1751–1754. Dockery DW, Cunningham J, Damokosh AI, Neas LM, Spengler JD, Koutrakis P, et al. 1996. Health effects of acid aerosols on North American children: respiratory symptoms. Environ Health Perspect 104:500–505. Edwards SC, Jedrychowski W, Butscher M, Camann D, Kieltyka A, Mroz E, et al. 2010. Prenatal exposure to airborne polycyclic aromatic hydrocarbons and children’s intel- ligence at 5 years of age in a prospective cohort study in Poland. Environ Health Perspect 118:1326–1331. Environmental Integrity Project. 2007. Dirty Kilowatts: America’s Most Polluting Power Plants. Available: http://www. dirtykilowatts.org/ [accessed 21 September 2010]. Hermann RP, Divita FJ, Lanier JO. 2004. Predicting premature mortality from new power plant development in Virginia. Arch Environ Health 59:529–535. Huang X, Lessner L, Carpenter DO. 2006. Exposure to persistent organic pollutants and hypertensive disease. Environ Res 102:101–106. Ito K, Mathes R, Ross Z, Nádas A, Thurston G, Matte T. 2011. Fine particulate matter constituents associated with cardiovascular hospitalizations and mortality in New York City. Environ Health Perspect 119:467–473. Jerrett M, Finkelstein MM, Brook JR, Arain MA, Kanaroglou P, Stieb DM, et al. 2009. A cohort study of traffic-related air pollution and mortality in Toronto, Ontario, Canada. Environ Health Perspect 117:772–777. Krewitt W, Hurley F, Trukenmüller A, Friedrich R. 1998. Health risks of energy systems. Risk Anal 18:377–383. Ma J, Kouznetsova M, Lessner L, Carpenter DO. 2007. Asthma and infectious respiratory disease in children—correla- tion to residence near hazardous waste sites. Paediatr Respir Rev 8:292–298. National Center for Health Statistics. 2006. International Classification of Diseases, 9th Revision: Clinical Modification, 6th edition (ICD-9-CM). Available: http:// www.cdc.gov/nchs/icd/icd9cm.htm [accessed 30 August 2010]. O’Connor AB, Roy C. 2008. Electric power plant emissions and public health. Am J Nurs 108:62–70. Ostro B, Roth L, Malig B, Marty M. 2009. The effects of fine particle components on respiratory hospital admissions in children. Environ Health Perspect 117:475–480. Pala K, Türkkan A, Gerçek H, Osman E, Aytekin H. 2010. Evaluation of respiratory functions of residents around the Orhaneli thermal power plant in Turkey. Asia Pac J Public Health 24:48–57; doi:10.1177/1010539510363622 [Online 10 May 2010]. Perera F, Li T-Y, Zhou Z-J, Yuan T, Chen Y-H, Qu L, et al. 2008. Benefits of reducing prenatal exposure to coal-burning pollutants to children’s neurodevelopment in China. Environ Health Perspect 116:1396–1400. Pope CA III, Burnett RT, Thun MJ, Calle EE, Krewski D, Ito K, et al. 2002. Lung cancer, cardiopulmonary mortality, and long-term exposure to fine particulate air pollution. JAMA 287:1132–1141. Samoli E, Nastos PT, Paliatsos AG, Katsouyanni K, Priftis KN. 2011. Acute effects of air pollution on pediatric asthma exacerbation: evidence of association and effect modifi- cation. Environ Res 111:418–424. Schneider C. 2004. Power Plant Emissions: Particulate Matter- Related Health Damages and the Benefits of Alternative Emission Reduction Scenarios. Available: http://www.catf. us/resources/publications/files/Power_Plant_Emissions. pdf [accessed 15 April 2011]. Schneider C, Banks J. 2010. The Toll from Coal: An Updated Assessment of Death and Disease from America’s Dirtiest Energy Source. Available: http://www.catf.us/resources/ publications/files/The_Toll_from_Coal.pdf [accessed 14 January 2011]. Shcherbatykh I, Huang X, Lessner L, Carpenter DO. 2005. Hazardous waste sites and stroke in New York State. Environ Health 4:18; doi:10.1186/1476-069X-4-18 [Online 29 August 2005]. Smargiassi A, Kosatsky T, Hicks J, Plante C, Armstrong B, Villeneuve PJ, et al. 2009. Risk of asthmatic episodes in children exposed to sulfur dioxide stack emissions from a refinery point source in Montreal, Canada. Environ Health Perspect 117:653–659. U.S. Energy Information Administration. 2010. Form EIA-860 Annual Electric Generator Report. Available: http://www. eia.gov/cneaf/electricity/page/eia860.html [accessed 13 October 2010]. Wang XY, Hu W, Tong S. 2009. Long-term exposure to gaseous air pollutants and cardio-respiratory mortality in Brisbane, Australia. Geospat Health 3:257–263. Yager JW, Hicks JB, Fabianova E. 1997. Airborne arsenic and urinary excretion of arsenic metabolites during boiler cleaning operations in a Slovak coal-fired power plant. Environ Health Perspect 105:836–842. Zanobetti A, Schwartz J. 2005. The effect of particulate air pollution on emergency admissions for myocardial infarc- tion: a multicity case-crossover analysis. Environ Health Perspect 113:978–982. 810 ovlume 120 | number 6 | June 2012 • Environmental Health Perspectives