Air quality affects people’s health. One major threat is exposure to the trace gas nitrogen dioxide emitted by traffic, biomass burning, and industrial sources. High nitrogen dioxide exposure is linked to increased rates of asthma, lung cancer, and overall mortality. We need to improve air quality and atmospheric monitors for these chemicals across Canada. Right now, satellites monitor large geographic areas for trace gases, including nitrogen dioxide. However, these measurements must be calibrated locally to reflect actual conditions accurately and to better inform public health policies. For this project, I will measure atmospheric composition near Toronto and at three Canadian Arctic sites. There, measurements from the ground will validate and improve satellite estimates of surface trace gases. Using data collected by “Pandora” UV-visible spectrometers, I will track concentrations of ozone, nitrogen dioxide, and other trace gases. I will present my progress and plans for this project.