The Norfolk Southern freight train was carrying numerous hazardous chemicals. To avoid a catastrophic explosion after the Feb. 3 derailment, authorities opted for a controlled release of gases, and they also burned the train cars’ contents, which included toxic vinyl chloride.
But residents were worried about their health and environmental hazards, so researchers have been assessing the local air.
Using U.S. Environmental Protection Agency data, a team of researchers from Carnegie Mellon University in Pittsburgh and Texas A&M University determined that nine of 50 gases reached levels above their baseline, especially acrolein, a respiratory irritant.
Researchers noted that if these nine compounds remained at those levels, breathing the air could pose health risks.
However, the amounts of many pollutants decreased significantly as the month wore on. Vinyl chloride, for example, declined to concentrations below long-term limits of health concern.
The researchers assessed the local air quality with stationary and mobile sampling methods, and reported their findings July 12 in the American Chemical Society’s Environmental Science & Technology Letters.
The team, which included Albert Presto, a research professor from Carnegie Mellon, used air-quality monitoring data from two EPA stations at fixed locations. They also drove a cargo van around the area for two days in late February, seeking to map patterns of airborne compounds.
Inside the van was a mass spectrometer, which the research team could use to identify a wide array of gases, upwind and downwind of the accident site.
The team then took the data and calculated the health risks for the gases.
The mobile monitoring was helpful because it detected changes over time and space. Researchers noted that during the day, acrolein and butyl acrylate were up to six times higher near the accident site than background levels. Yet at night they dropped to the background amount.
The study notes that these results show the importance of having both stationary and mobile air-quality assessment. Both should continue as cleanup activities proceed, the authors said in a journal news release.
The research was supported in part by the U.S. National Institute of Environmental Health Sciences.
The U.S. Environmental Protection Agency has more on the chemical acrolein.
SOURCE: American Chemical Society, news release, July 12, 2023
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