Spatial variability of ambient ozone concentrations during 3 heat waves in the Northeast Megaregion of the United States

Climate change, both local and global, have become the focal point of research over the past decade; in particular, the incidence of extreme temperature conditions resulting in excessive heat and/or humidity. Heatwaves are characterized by temperatures that exceed the normal daily average and can result in severe consequences such as power outages and droughts. The most problematic effect of a heatwave is its impact on human health, causing hyperthermia and heat stroke, and contributing to the death of hundreds each year. Heatwaves have no standard definition and vary depending on the geographical region in which they occur. Extreme temperatures also contribute to the accumulation of ambient ozone precursors (NOx and VOCs) which can have deleterious effects on the human respiratory system. Our hypotheses are three-fold: First, although ambient ozone levels will experience an overall rise during a heatwave event, these concentrations will vary based on geographical location, as a result of variance in factors such as latitude, topology, urbanization patterns and proximity to emissions. Second, there will also be a degree of variation between each heatwave event, with the location of highest ozone concentrations varying for each event. Third, we predict that the burden of ozone pollution will be unequally distributed among different populations due to both location and socioeconomic - based variance in factors determining ozone concentrations.

Focusing on the 13-state Northeast Megaregion (Deware et al. 2007), we used the definition of heatwave described by Robinson et al. (2001) and meteorological data from the Daymet dataset to delineate our 3 study events. Site-based ozone concentration and meteorological data were obtained from the EPA AirData database. to assess spatial-based variation in ozone concentrations during recent heat waves. Using block-level census data, we investigated the relationship between ozone concentrations, meteorological parameters during heatwave events and population exposure within a 1-km range focusing specifically on socioeconomic status, age, and ethnicity. The National Emissions Inventory (http://www.epa.gov/ttn/chief/eiinformation.html) was used to investigate the relationship between ozone and proximate emission sources. The National Land Cover Dataset (NLCD) was used to consider variance in exposure in urban and rural areas. We also consider bias in sampling site locations between urban and rural areas.