California, a state known for its aggressive greenhouse gas reduction policies, is ironically the nation's greatest emitter of one: sulfuryl fluoride. As much as 17% of global emissions of this gas, a common pesticide for treating termites and other wood-infesting insects, stem from the United States. The majority of those emissions trace back to just a few counties in California, finds a new study led by Johns Hopkins University. "When we finally mapped it out, the results were puzzling because the emissions were all coming from one place," said co-author Scot Miller, an assistant professor of environmental health and engineering at Johns Hopkins who studies greenhouse gases and air pollutants. "Other greenhouse gases like carbon dioxide and methane are found everywhere across the U.S. On our sulfuryl fluoride map, only California lit up like a Christmas tree." Miller and lead author Dylan Gaeta, a PhD candidate at Johns Hopkins, analyzed more than 15,000 air samples collected between 2015 and 2019 by NOAA Global Monitoring Laboratory scientists. The researchers factored in wind speed, direction, and other meteorological variables to trace the chemicals back to their point of origin. The team found 60-85% of sulfuryl fluoride emissions in the U.S. come from California, primarily Los Angeles, Orange, and San Diego counties, despite California being a national leader in reducing greenhouse gas emissions, including publishing a comprehensive plan to achieve net-zero emissions by 2045. "We can now show not only where but also how and why this gas is being emitted," Gaeta said. "In order to get to net-zero emissions, we need a complete inventory of what greenhouse gases are out there." The findings published today in Communications Earth & Environment. First approved by the U.S. Environmental Protection Agency for use as a pesticide in 1959, sulfuryl fluoride gained popularity after countries around the world agreed to... |