The goal of this project is to create air pollution maps by measuring NOx, PM2.5, and PM10 concentrations in the Tucson area, and then use this data in a land use regression analysis to model air pollution concentrations to assess various health metrics from multiple ARC cohorts, including: the Children’s Respiratory Study (CRS), Infant Immune Study (IIS), and Tucson Epidemiological Study of Airway Obstructive Disease (TESAOD). Study procedures are adapted from the ESCAPE study. This project will sample NOx air concentrations in the Tucson area at approximately 40 different sites at private residences, Pima Department of Environmental Quality (PDEQ) air monitoring stations, and other locations. At 20 of these 40 sites, concentrations of PM with less than 2.5 (PM2.5) and 10 (PM10) microns in diameter will also be sampled. Air pollutant measurements will be taken for one 2-week period in three different seasons (i.e. summer, fall, and winter) and adjusted for weather conditions using continuous monitoring stations to create average seasonal and annual concentrations.