Exposure to vehicle emissions at international border crossings is a concern for many, including daily cross-border travelers and U.S. Customs and Border Protection (CBP) officials. This project will measure PM2.5 levels at different times of day and locations within selected border crossings (IBCs) to assess the potential exposure of people waiting to cross in private vehicles or on foot, as well as CBP officers working at inspection points. Additionally, the project aims to identify statistically significant relationships between PM2.5 levels and other variables, such as traffic volume or congestion, proximity to monitors, and ambient conditions. These findings could help predict how PM2.5 is distributed across an IBC and inform strategies to reduce exposure.