Investigators found that 1,1,1 trichloroethane; 2-nitropropane; and 2,4,6 trichlorophenol were significantly associated with asthma symptoms for 3 exposure periods.
Different combinations of air pollutants were associated with asthma symptoms in a study of elementary school children in Spokane, Washington, according to results of a study published in Science of The Total Environment.1,2 The study investigators identified 25 different combinations, according to the results.
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"It's not just one pollutant that can be linked to asthma outcomes. This study examined the variety and combinations of air toxics that may be associated with asthma symptoms," Solmaz Amiri, DDes, Msc, a researcher in the Elson S. Floyd College of Medicine at Washington State University, said in the press release. "Both in Spokane and New York City, regardless of the setting – how large or small the cities are – these air toxics appear to be influencing asthma among children.”1
Other studies have focused on a limited number of pollutants, according to the press release, so investigators in the current study used machine learning to analyze the potential exposure effects of 109 air pollutants and their combinations to determine their impact on asthma outcomes.1
Investigators collected and analyzed data from 269 children with asthma who experienced symptoms including coughing, wheezing, difficulty breathing, and the need for an inhaler. They also collected data from the Environmental Protection Agency about air toxins in neighborhoods surrounding 10 elementary schools in the Spokane region, according to the press release. Data were collected in 2019 and 2020 before the pandemic lockdown occurred in March 2020.1
The study investigators associated their collected data with air pollutant exposures that occurred within 6 months and with 2 longer-term exposure periods 3 and 5 years prior to the children’s asthma symptoms, according to the press release. They found that 1,1,1 trichloroethane; 2-nitropropane; and 2, 4, 6 trichlorophenol were significantly associated with asthma symptoms for the 3 exposure periods.1
In the press release, 1,1,1 trichloroethane is a widely used solvent in industry, formerly used in household cleaners and glues, whereas 2-nitropropane is an additive to paints and other finishes. Additionally, 2, 4, 6 trichlorophenol is an anti-septic and anti-mildew agent banned in the 1980s, but still found in some pesticides and preservatives that were made before that period.1
"Some of these air toxics were discontinued in the United States, but they can still be found in materials that may be in storage or people have in their backyard or garage. Other air toxics still exist at least in the environment," Amiri said in the press release.1
Although the study did not pinpoint the source of the air pollutants or why the group of children from a lower income neighborhood were highly exposed, Amiri said proximity to sources, such as highway with a lot of traffic or factories using solvents, could play a role in toxin exposure. The study was also limited to a mid-sized city, Amiri also said that these findings aligned with another study done in New York City which found similar air pollutants were associated with asthma outcomes, according to the press release.1
The current study comes after previous research done by Washington State University that found a group of children in a lower income neighborhood were exposed to more toxic combinations, with 13 of the 25 identified from this research.1
