Collaborative research: US emissions of sulfuryl fluoride, a pesticide and potent greenhouse gas

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Sulfuryl fluoride is a pesticide used to exterminate termites and other pests from homes and buildings, agriculture, and international shipping. Globally, atmospheric concentrations of sulfuryl fluoride have been increasing exponentially as it replaces the toxic pesticide methyl bromide. Methyl bromide is being phased out as it depletes the stratospheric ozone layer, which shields life on Earth from harsh ultraviolet light. Although sulfuryl fluoride does not deplete the ozone layer, it is a potent greenhouse gas and can cause negative health impacts at high exposure. There are numerous knowledge gaps regarding the use of sulfuryl fluoride that prevent a full assessment of its environmental impact. The goal of this project is to address these knowledge gaps by modeling emissions, fate, and transport of sulfuryl fluoride. This will be achieved through specific research to measure sulfuryl fluoride concentrations in ambient air, evaluate how use and emissions are changing over time, and estimate the fraction of emissions that are absorbed during fumigation. Successful completion of this research will provide key information for assessing the environmental impact of sulfuryl fluoride to better inform federal and state regulatory agencies. These findings will also facilitate greenhouse gas emissions accounting for sulfuryl fluoride, which currently do not include this compound in official estimates. Additional benefits to society will result from mentoring high school research interns each summer from Baltimore Public Schools, increasing scientific literacy and enhancing the Nation’s STEM workforce.Sulfuryl fluoride is a toxic pesticide and potent greenhouse gas; it is a common fumigant used to exterminate termites and pests that infest residential structures and agricultural products. In spite of the exponential increase in usage as a replacement for methyl bromide, there are major gaps in understanding the environmental fate of sulfuryl fluoride. The goal of this research project is to address these gaps by evaluating US emissions of sulfuryl fluoride and place these emissions in a global context. This goal will be achieved through two primary research objectives to: i) estimate the magnitude and distribution of sulfuryl fluoride emissions across the United States using atmospheric observations of the gas coupled with inverse modeling, and ii) evaluate recent trends in US emissions in the context of global emissions increases. This research is designed to test three hypotheses that H1) California accounts for a larger share of US sulfuryl fluoride emissions than any other region of the country, H2) increasing US emissions account for the majority of global emissions increases, and H3) at least some of the sulfuryl fluoride used for fumigation is absorbed into structures or agricultural products. Successful completion of this project will provide critical information necessary to characterize the human and ecological health impacts of sulfuryl fluoride use by scientists, regulators, public health professionals, and other stakeholders. Preliminary analysis by the research team indicates that increased sulfuryl fluoride use in the state of California may completely negate recent progress toward meeting emission reduction goals in the state.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.