Widespread use of sulfuryl fluoride began in the 1990s following the Montreal Protocol, an international treaty ratified in 1987 to protect the ozone layer by reducing the production of ozone-depleting chemicals. The protocol ordered the gradual discontinuation of methyl bromide, which has strong ozone-depleting characteristics, and sulfuryl fluoride became a preferred replacement for structural fumigation. Sulfuryl fluoride is regulated as a toxic substance but not currently as a greenhouse gas.
"Such fumigants are very important for controlling pests in the agricultural and building sectors," said Ron Prinn, director of MIT's Center for Global Change Science and a co-author on the new paper. But with methyl bromide being phased out, "industry had to find alternatives, so sulfuryl fluoride has evolved to fill the role."
"Unfortunately, it turns out that sulfuryl fluoride is a greenhouse gas with a longer lifetime than previously assumed," added Mhle. "This has to be taken into account before large amounts are emitted into the atmosphere."
Mhle credited the assistance of the chief manufacturer of sulfuryl fluoride in the United States, Dow AgroSciences, in the study.
"They've been very cooperative in sharing with us their estimates of global industrial sulfuryl fluoride production," he said.
The team's report follows closely on the announcement of a similar finding about the greater-than-expected prevalence of nitrogen trifluoride, a gas used as a cleaning agent during the manufacture of thin-film solar cells, flat panel monitors and other electro
|Contact: Rob Monroe or Mario Aguilera|
University of California - San Diego