Assessing the Impact of Traffic Delays at US-Mexico Border Crossing on Air Quality in Brownsville Using Low Cost Sensors and Satellite Imagery.

Air pollution is one of the greatest risks to environmental health. Ambient/Outdoor air pollution is estimated to have caused approximately 4.2 million premature deaths all across the world. Motor vehicles, industrial facilities and energy production are some of the highest contributing factors of outdoor air pollution. The traffic-related air pollution is a major contributor to pollutants such as carbon dioxide (CO₂), particulate matter (PM), ozone (O₃), nitrogen dioxide (NO₂), carbon monoxide (CO), polycyclic aromatic hydrocarbons (PAHs), and volatile organic compounds (VOCs). The transportation industry is responsible for more than 55% of the entire NO_X emissions inventory in the United States (USEPA). Especially border cities with port of entries are more likely to be affected with traffic related air pollutants. The long delays of commercial and passenger vehicles and their excessive emissions at the port of entries increases the exposure period to air pollutants to the port of entry users, workers and residents living nearby. These acute/chronic exposures to the emissions could lead to increased risk to respiratory health conditions such as asthma and other lung function ailments. Hence, it is very important to address the air quality issues at the border cities with multiple port of entries.

Brownsville, a city in Cameron County of Texas is located adjacent to the border with Matamoros, Mexico. It is home to 186,738 people out of which 94% are Hispanic and is a majority-minority community. It has multiple international crossings i.e., the Gateway International Bridge, the Brownsville & Matamoros International Bridge, and the Veterans International Bridge. Texas Commission on Environmental Quality (TCEQ) operates one Continuous Ambient Monitoring Station (CAMS) in Brownsville – C80 which is 1.2 miles away from the Veterans International Bridge and monitors only one of six criteria air pollutants i.e., PM_2.5. C80 does not measure other air pollutants such as NO₂, O₃, SO₂, CO and lead. A report published by Environment Texas Research & Policy Center documents that Brownsville-Harlingen region had 128 days and McAllen-Edinburg-Mission, TX had 92 days with elevated PM_2.5 pollution with the AQI above 50, respectively.

The aim of this research is to integrate data collected by ground-based monitoring stations and the Aura Ozone Monitoring Instrument (OMI), Sentinel-5 Precursor to evaluate the effect of the traffic delays near the Veterans International Bridge on the air quality in the region. Low-cost sensors are recently gaining popularity due to their role in citizen science and increasing the spatial resolution of air quality measurements. Collocation activities with FEM instruments were carried out in three different environments for all the sensors before deploying them in the field to increase the accuracy and precision of the data. Three TSI-8145 sensors were deployed in different distances from the port of entry to estimate the effect of emissions on various parts of the city. The trends of various air pollutants including PM_2.5, NO₂, CO₂, CO, O₃, and SO₂ will be presented. Initial analysis show there is an increase of NO₂ levels on weekdays in comparison to weekends, particularly during the evening periods when the waiting time for entry is longer. The premise of this project is that increased exposure to traffic related air pollutants is an example of environmental injustice, particularly for the low-resourced majority minority area situated along the U.S.-Mexico border.