John Hopkins University

By Bill Walker

Among US states, California is a leader in efforts to cut emissions of the greenhouse gases that fuel the climate crisis. But just three counties in Southern California emit far more of one little-known greenhouse gas than all other US states combined.

Blame termites – and the tragic, too-frequent mistake of replacing one environmentally harmful chemical with another that turns out to be just as bad.

Sulfuryl fluoride is a fumigant pesticide first made by Dow Chemical Co., marketed since 1959 as Vikane. To kill western drywood termites, pest control companies cover infested houses with tents and then pump in Vikane. Houses tented for fumigation are a common sight in Southern California, where warm, dry weather leaves wooden buildings highly susceptible to infestations of the hard-to-exterminate species.

The colorless, odorless, highly neurotoxic gas that kills termites is also a danger to humans. That’s why Vikane must be spiked with another toxic pesticide gas called chloropicrin, which has an intensely irritating smell that is meant to warn people against entering a house until the fumigant has dispersed in 24 to 72 hours.

California Department of Pesticide Regulation (DPR) records show that between 1992 and 2017, at least 16 Californians died from sulfuryl fluoride poisoning after going inside fumigated houses too soon. In the same period DPR recorded more than 200 cases of human exposure that caused breathing problems, dizziness, nausea, and other symptoms.

But the biggest problem with Vikane is that, when fumigation tents are removed and sulfuryl fluoride disperses into the atmosphere, it is a greenhouse gas much more powerful than carbon dioxide (CO2).

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