Our proposal will determine the most important variables that explain spatial and temporal variance of near road traffic-related pollutant concentrations: We will explore the relative influence of traffic activity, human activity, the built environment (roadways and other built structures), and environmental (e.g. temperature, wind and background concentrations) factors on multi-pollutant transport, differential evolution and how all of these influence human exposure. We will also demonstrate novel surrogates of near-road traffic-related pollution: We will develop data and modeling approaches to quantify exposure concentrations of multiple pollutants emitted from vehicles or formed as secondary pollutants in the near-roadway microenvironment: fine particulate matter (PM), ultrafine particles (UPF), semi-volatile organic compounds (SVOCs), nitrogen dioxide, and carbon monoxide. The role of individual pollutants and mixtures of pollutants, and whether some pollutants are good surrogates for others, will be assessed. We will improve inputs for exposure models for traffic-related health: We will explore the implications of our measurement findings by applying them in spatial and temporal analysis of the relationship between human exposure (or surrogates for human exposure) and adverse effects, including evaluation of mixtures of pollutants and other proxies for exposure