Assessing Impacts of Sugarcane Stubble Burning on Air Quality using Low-Cost Sensors and Satellite Data in the Lower Rio Grande Valley of South Texas, USA

The Lower Rio Grande Valley (RGV) region of South Texas includes Hidalgo, Cameron, Willacy, and Starr counties, and is home to 1,399,446 people (Census Bureau 2022). The area has an employment rate at 50.88%, and median household income at $ 42,050. This area is characterized as a major minority community with limited resources, with Hispanics/Latinos making up 91.8% of its population. There has been an increase of 13.2% in the population when compared to 2010 and it is accompanied with high economic activities and high environmental exposures due to traffic emissions, agricultural and trash burning, and high diesel emissions near the international ports of entries.

The Texas Commission on Environmental Quality (TCEQ) which is the environmental agency for the state operates five Central Ambient Monitoring Site (CAMS), one each in Brownsville, Edinburg, Harlingen, Mission, and Port Isabel. With only two CAMS monitoring O₃ and four monitoring PM_2.5 (out of which data from instruments at two CAMS does not meet EPA quality assurance criteria and cannot be used for regulatory purposes), renders the CAMS monitoring insufficiency in depicting accurate levels of air pollution exposure for the 1.3 million individuals living in the area. Even though this region is usually in compliance with the USEPA’s National Ambient Air Quality Standards (NAAQS) for criterial air pollutants, it is important to increase the general awareness about the health impacts due to acute/chronic exposures of CAP’s. A recent 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 (ETRPC, 2021).

Rio Grande Valley is one of the largest harvesters of sugarcane not only in Texas, but also in Continental United States. Around 40,000 acres of the total area is used to produce more than 1.5 million tons of sugarcane. The sugarcane stalk is burnt during the pre- and post-harvest season of the crop every year. This is done to facilitate the harvesting of sugar-rich stalks and to decrease the moisture content in the stems, making the process more cost-effective and efficient. As a result of this procedure, air pollutants are released into the atmosphere, leading to an increase in public exposure to these pollutants. With 24.7% of the total families residing in the region living below poverty and 30.2% of the total population lacking health insurance coverage, it is very important to access the air quality of the region during the months of burning activity.

As part of An Environmental Justice (EJ) project by funded by NASA, the research work integrates data from NASA satellite data and ground-based monitoring stations like locally deployed low-cost sensors and local ambient monitoring sites to address PM_2.5 trends due to agricultural burning in this region. Low-cost sensor networks are recently gaining popularity due to their role in citizen science and increasing spatial resolution in measuring air quality. 20 Low-cost purple air sensors measuring Particulate matter of different sizes have been deployed across the region. Along with these, 5 Aeroqual instruments were also deployed to measure the pollutant gases like NO₂ and O₃. A 30 - day calibration activity was carried out in three different environments for all the sensors before deploying them in the field. These sensors were collocated with FEM instruments to increase the accuracy and precision of the data. A GIS enabled dashboard is also developed to visualize the real time air pollutant levels. This project is based on the premise that high exposures to air pollutants is a matter of environmental injustice especially for this low-resourced majority minority region of the U.S.-Mexico border. The findings presented in this presentation will provide the requisite yardstick to address this very important air quality issue facing this part of South Texas.