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Description
Vehicle emissions are the largest cause of air pollution today and are some of the main contributors to criteria pollutants in the United States. Criteria pollutants are harmful to human health and the environment and depending on their concentrations, all are attributed to increases in morbidity and mortality. Vehicle congestion, as a result of inefficiencies at the California-Mexican border, is producing increased amounts of vehicle emissions. These international border crossings in San Diego County incorporate two of the largest passenger and commercial border land ports in the world. This study estimates 4 criteria pollutant emissions: carbon monoxide (CO), oxides of nitrogen (NO_), sulfur dioxide (SO_), particulate matter with 2.5µm diameter (PM2.5) and 10µm diameter (PM__) due to the northbound vehicle delays at the three San Diego County-Baja California border crossings in 2009. These crossings include the San Ysidro, Otay Mesa and Tecate ports of entry. Estimations of emissions were created by the most recent EPA emissions modeling program, Motor Vehicle Emission Simulator (MOVES2010a). Total modeled emissions for all three of the border crossings for the year 2009 for CO, NO_, SO_, PM2.5 and PM__ are: 1060, 158, 0.469, 4.72, and 4.92 tons, respectively. Passenger vehicles and motorcycles emitted 77% and 20% of the CO emissions, respectively. Commercial vehicles and passenger vehicles produced 48% and 50% of the NOx emissions. The SO_ emissions from the passenger vehicles totaled 90% with the remaining 10% produced from the commercial trucks. Commercial trucks and passenger vehicles produced 68% and 30% of PM2.5 and PM__, respectively. The majority of the PM2.5 and PM__ were emitted from the Otay Mesa port of entry, while the San Ysidro border crossing produced the most CO, NO_ and SO_ emissions. The Tecate border crossing contributed the least vehicle emissions for each pollutant. Vehicle idling was the major contributor of all pollutant emissions. In comparing these emissions to the San Diego Air Basin Inventory on-road transportation emissions, the percentage of pollutants attributed to the border crossing for CO, NO_, SO_, PM2.5 and PM__ are as follows: 0.54%, 0.43%, 0.27%, 0.33% and 0.24%. The limitations of this study include the lack of specific age and the condition of the vehicles crossing the border. Lack of data regarding southbound vehicle volumes and delay times was not available. Real-time delay data was not available and commercial truck data was conflicting. These limitations underestimate the criteria pollutants for this project. Efforts to improve the California-Mexico border crossings to allow the flow of passenger vehicles and commercial trucks are crucial to reducing vehicle wait time and vehicle emissions
