Air Toxic Emissions and Associated Health Risks in Cook County, Illinois, 1999-2014
thesisposted on 01.08.2020, 00:00 by Yi-Ling Cheng
The Clean Air Act of 1990 listed 187 air toxics that USEPA is required to control to protect public health. To uncover the spatial and temporal trends in air toxic emissions and identify higher contributing emission sources and chemicals to the total inhalation cancer risk in Illinois, we assessed USEPA’s National Emissions Inventory (NEI) data. We also analyzed the data of USEPA’s National Air Toxics Assessment (NATA), which estimates inhalation cancer risk and non-cancer risks across the U.S. on census tract level. In addition, due to the prominence of diesel PM as agent that is “likely to be human carcinogen” and lack of diesel PM cancer and non-cancer risk estimates under NATA, we calculated diesel PM cancer and non-cancer risks using California EPA-developed toxicity values. We assessed spatial distribution of diesel PM and select air toxics (those which contribute most to cancer and non-cancer risks) in Cook County, IL, to support inhalation exposure and health risk mitigation efforts and guide environmental justice and health disparities research and policy. Based on our findings, Cook County, IL, is consistently the county that contributes the most to the total air emissions in Illinois in 1999, 2002, 2005, 2011 and 2014 followed by counties near it like DuPage County, Lake County, and Will County, which are more urbanized counties in Illinois. In terms of spatial and temporal distribution of NATA datasets, all the total inhalation cancer risk areas in Cook County, IL, which excludes the contribution from diesel PM, were in the acceptable range (10^-6 - 10^-4) but the inhalation cancer risk of those higher areas were close to the edge of being above the acceptable range. “On-road” emission was the greatest contributor to total inhalation cancer risk in Cook County, IL, among all studied years. Top three chemicals contributing to 2014 total inhalation cancer risk estimates in Cook County are ethylene oxide, benzene, and formaldehyde in the descending order. The spatial distribution of ethylene oxide inhalation cancer risk estimates in Cook County census tracts aligns well with that for the total inhalation excess cancer risk estimates for Cook County in 2014. This provides the evidence for the critical role that the facilities emitting ethylene oxide into the atmosphere play in cancer risk estimates locally. Most diesel PM excess cancer risk estimates in Cook County were above USEPA’s acceptable range (10^-6 to 10^-4), which is a significant public health concern. The mobile sources in urban areas in Cook County contributed the most to the diesel PM inhalation excess cancer risks. This is visually depicted with higher diesel PM cancer risks along major highways in the region in GIS maps of diesel PM cancer risks from 1999-2011. In terms of respiratory non-cancer risk analysis, acrolein, diesel PM, and formaldehyde are the highest contributing air toxics to the total respiratory non-cancer risk in Cook County, 2014, however, the respiratory non-cancer risks were all within the acceptable range per USEPA guidelines (i.e., hazard quotient less than unity).