Using Traffic Density and Foliar Chemistry Variables to Understand Interactions Between Air Pollution and Household Income

We utilize traffic density and Convolvulus arvensis leaf chemistry to understand spatial patterns linking atmospheric pollution and household income in the Salt Lake City metropolitan area, USA. We hypothesize that traffic density will explain variation in atmospheric NO x and O 3 concentrations. In addition, we expect foliar %N and nitrogen isotope ratios (δ 15 N) to be elevated and carbon isotope ratios (δ 13 C) to be depleted on high traffic density roads. These hypotheses were supported: we found the highest NO x and lowest O 3 concentrations on high‐traffic density roads. Also, NO x concentrations were higher in low‐income neighborhoods. Low‐income neighborhoods contained a greater density of high‐traffic roads than high‐income neighborhoods. Foliar %N was highest in low‐income neighborhoods and was correlated with NO x and O 3 , while δ 15 N was more depleted with increasing O 3 . These findings indicate that the distribution of high‐traffic density roads plays a significant role in inequities in pollution exposure between high‐ and low‐income neighborhoods, which is reflected in leaf chemistry.