According to The American Lung Association “State of the Air” report in recent years, Connecticut has continued getting failing grades for air quality mostly due to the heavy ozone pollution even after great effort has been made to control air pollution. There are some special populations in Connecticut that are at high risk when ozone is at a high level. This led to the urgent need to lower down ozone concentration in Connecticut and find out the major sources of ozone in Connecticut. We use the Comprehensive Air Quality Model with Extensions (CAMx) and the Community Multiscale Air Quality Modeling System (CMAQ) to estimate the impact of nine point sources in the New York/New Jersey on ozone concentrations in Connecticut to find out the major sources of ozone in Connecticut. We also do modeling focused on larger sources, estimating the contributions from surrounding states in the Northeastern US to ozone in Connecticut. For each model, we use the available source apportionment tools, Ozone Source Apportionment Tool (CAMx-OSAT), and Integrated Source Apportionment Method (CMAQ-ISAM), to quantify sources contributions (i.e. what fraction of ozone comes from emissions from each source). In CAMx, we also use sensitivity, using the Decoupled Direct Method, to estimate the sensitivity of ozone concentrations at the monitoring sites to emissions from the nine selected point sources. Both models and their tools estimate that boundary conditions and unapportioned sources(areas except for the selected sources inside the domain) contribute the most to ozone in Connecticut. The contribution of conditions condition remains constant, unapportioned sources and selected source contribute more to ozone in Connecticut when ozone is at a high level. All nine selected sources combined contribute little to ozone in Connecticut, but the surrounding states contribute to a large part of ozone in Connecticut when ozone is high.
