Description
The San Ysidro Land Port of Entry (LPOE) is the busiest Port in the Western Hemisphere (approximately 1.8 million vehicles each year). San Ysidro is a district of the City of San Diego, and its community is mainly Latino (90%) and low-income. The purpose of this study was to compare the level and composition of fine particulate matter (PM2.5) in rooftops of four sites: two schools, a community art center in San Ysidro, and a coastal reference site over two seasons (Spring 2017& Fall 2017). PM2.5 mass concentration was measured on a minute-by-minute basis with the DustTrak DRX (TSI) and gravimetrically on a Teflon filter over a 24-h collection period with the MiniVol (Airmetrics) for five days. In two sites, San Ysidro and the coastal site, Teflon filters were subjected to chemical analysis by X-ray Fluorescence and Ion Chromatography. Also, the MiniVol with a quartz filter was collected and examined for the organic carbon (OC) and elemental carbon (EC). The PM2.5 concentration was higher during the fall than the spring (overall gravimetric mean PM2.5 concentration 47.3 ug/m3 vs. 21.7 ug/m3). Both EC and OC at The Front were consistently higher than the reference site in both seasons. When expressed as a fraction of PM2.5, both seasons had a higher fraction of OC/PM2.5 at The Front (41% vs 30% in spring, and 44% vs. 25% in fall). Similarly, for EC at The Front (11% vs 8% in spring, and 16% vs. 8% in fall). The overall results from this study exhibited a clear seasonal pattern with the highest PM2.5 concentration in the fall, and more toxic PM2.5 from the San Ysidro location. This pilot study was the first to investigate PM2.5 chemical concentration in this region and will help to identify the type of chemicals in PM2.5 and their potential sources.
