Fine particulate matter results from natural sources and transportation, study shows

Research funded by the Asphalt Institute determines that, in the Dallas-Fort Worth metropolitan area, the dominant sources of fine particulate matter known as PM2.5 are from natural sources and transportation.

Fine particulate matter (PM2.5) is a potential air pollutant regulated at Dallas-Fort Worth (DFW) facilities, including asphalt facilities. PM2.5 is regulated based on research showing potential contribution to juvenile asthma and other lung-related health effects. PM2.5 emissions at an asphalt facility in the DFW area are stringently regulated by the Texas Commission on Environmental Quality (TCEQ) or the City of Dallas. Even though the sources are regulated, and PM2.5 emissions are limited by control technology required by the permit, local environmental groups have caused unwarranted public scrutiny to force the closure of asphalt facilities in the DFW area based on their potential PM2.5 and other emissions.

To evaluate the concerns expressed by the environmental groups, the Asphalt Institute funded a study of TCEQ monitoring data in the DFW area. That study was conducted by Roux, Inc. The study included an in-depth analysis of the TCEQ regulatory compliance-related air quality data for PM2.5 in the DFW area. The comprehensive analysis determined that, except for January, a majority of the annual PM2.5 measured in DFW’s air is dominated by natural sources, including dust storms, forest fires and transportation-related vehicle emissions. The Roux results have been published in the peer-reviewed journal “Air.” 1

The Roux results are consistent with the opinion of the Agency for Toxic Substances and Disease Registry (ATSDR), an agency focused on protecting health in the United States. The ATSDR has stated that if ambient PM2.5 levels seem high at a local site but adjacent PM2.5 monitors up and downwind consistently have similarly high PM2.5 concentrations, such local elevated levels reflect that the regional air quality for that city or geographic area may be poor.2 Local sources do not dominate the air quality.

The Roux scientific article supports the conclusion that assessing the cause(s) of DFW community exposure to PM2.5 requires more analysis than simply looking at the increases and decreases in PM2.5 emissions resulting from sources such as asphalt facilities. Thus, regulators and community groups should also focus on the more significant regional PM2.5 sources in their reviews rather than simply applying pressure to local sources such as asphalt facilities.

The Asphalt Institute Health, Safety and Environment Committee will continue to monitor this issue in the DFW area and other locations. The full text of the Roux article published in the journal “Air” can be found online.

1. Shapero, Andrew, Stella Keck, and Adam H. Love. 2023. “Background Influence of PM2.5 in Dallas–Fort Worth Area and Recommendations for Source Apportionment” “Air”1, no. 4: 258-278

2. Agency for Toxic Substances and Disease Registry. 2020. Guidance for Inhalation Exposures to Particulate Matter. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, September 30.