The US-Mexico border crossing at San Ysidro is the busiest land border crossing in the world. This investigation sought to understand how traffic and idling cars delayed at the border crossing affect air quality in the US community of San Ysidro. Traffic-related air pollution has been reported to adversely affect lung, cardiac and reproductive health. Currently, there is no governmental air monitoring station in San Ysidro to characterize air pollution in the community. This study investigates spatial distribution of the following traffic related air pollutants in the City of San Ysidro: particulate matter
