Pest Control’s Largest Chemical Is a Greenhouse Gas: The Sulfuryl Fluoride Evidence

What the evidence establishes

• Sulfuryl fluoride has a 100-year global warming potential of 4,630 and a 20-year GWP of 7,510, with an effective atmospheric lifetime of 36 years, according to the IPCC Sixth Assessment Report.
• It is the single largest chemical by weight in California structural pest control, at 67.1 percent of applied pounds in 2022 and 64.1 percent in 2023.
• California emits more sulfuryl fluoride than any other US state, at 0.26 plus or minus 0.10 gigagrams per year, which is 60 to 85 percent of the US total and 5.5 to 12 percent of global emissions.
• The highest emissions come from Los Angeles, Orange and San Diego counties, which is exactly where the application records put the use.
• Only 11 to 25 percent of applied sulfuryl fluoride appears to reach the atmosphere. The researchers reconciled California’s reported use against their atmospheric estimate and found an emitted fraction far below the previously assumed two thirds.
• The gas is in no greenhouse gas inventory. It is excluded from the EPA Greenhouse Gas Reporting Program, the US National Greenhouse Gas Inventory and the 2015 Paris Agreement. California classified it as a short-lived climate pollutant in 2016 and has still not added it to the state inventory.
• The scale is comparable to California’s climate progress. The study puts California’s annual sulfuryl fluoride emissions at 1.2 to 2.7 teragrams of CO2 equivalent on a 20-year basis, against average statewide reductions of 2.25 teragrams per year from 2010 to 2015.
• This is a consequence of an earlier environmental success. Sulfuryl fluoride use expanded as methyl bromide, an ozone-depleting substance, was phased out under the Montreal Protocol by 2005.
• Our own contribution: we extend the California use record to 2023, showing statewide use of 1.575 gigagrams in 2022 and 1.393 in 2023, and we show the structural share of that use has fallen from roughly 85 percent to about 75 percent.

Why this matters to a pest control operator

In short: The industry’s highest-volume chemical carries a climate liability that no inventory currently counts, which is the classic precondition for future regulation. Two independent research groups have now quantified it.

Our analysis of California pesticide use records found that one compound accounts for most of the weight this industry applies. Sulfuryl fluoride was 67.1 percent of all structural pesticide pounds in California in 2022 and 64.1 percent in 2023, across roughly one application in 200. That finding is set out in our report on what structural pest control actually applies.

What that report did not cover is what the compound does once it is vented. Whole-structure fumigation works by filling a tented building with gas and then aerating it, which releases the gas that has not been absorbed or destroyed. Until 2009 the atmospheric lifetime of sulfuryl fluoride was thought to be negligible, so its environmental fate was largely unstudied. That turned out to be wrong.

There is now a body of peer-reviewed work on this, including a 2024 paper in a Nature journal that names California specifically. No pest control trade publication appears to have reported it. This report summarises what the science establishes, and extends the use record to the most recent year available.

The numbers, and who published them

1. 100-year GWP of 4,630. Sulfuryl fluoride has a 100-year global warming potential of 4,630, meaning one tonne is equivalent to 4,630 tonnes of carbon dioxide over a century. (IPCC, Sixth Assessment Report, Working Group I, Chapter 7 Supplementary Material, Table 7.SM.7.)
2. 20-year GWP of 7,510. Over 20 years the figure is 7,510, and over 500 years it is 1,410. (Same source.)
3. 36-year atmospheric lifetime. Its effective lifetime is 36 years, with a radiative efficiency of 0.211 watts per square metre per part per billion. (Same source.)
4. Removal is by ocean uptake and hydrolysis, not by atmospheric photochemistry, which is why the lifetime is long. (Gaeta et al., 2024.)
5. Global concentration has risen tenfold. The global mean atmospheric mole fraction rose from about 0.3 parts per trillion in 1978 to nearly 3.0 parts per trillion in 2023. (Gaeta et al., 2024.)
6. Still rising at 4 percent a year. Global concentrations increased at nearly 0.1 parts per trillion per year, or about 4 percent annually, from 2015 to 2023. (Same source.)
7. Global emissions near 3.0 gigagrams per year. Global emissions have reached a historic high of nearly 3.0 gigagrams per year, with a measurement-based estimate of about 2.89 gigagrams per year for 2015 to 2017. (Same source, citing Gressent et al.)
8. California emits 0.26 gigagrams per year. The 2024 study estimates California’s annual mean emissions at 0.26 plus or minus 0.10 gigagrams per year, against a US total of 0.30 plus or minus 0.18. (Gaeta et al., 2024.)
9. California is 60 to 85 percent of the US total and 5.5 to 12 percent of global emissions. (Same source.)
10. Outside California, emissions are near zero. The rest of the US combined was estimated at 0.05 plus or minus 0.16 gigagrams per year, and enhancements were detected only very infrequently. (Same source.)
11. Emitted fraction of 11 to 25 percent. Comparing reported California use of 1.435 gigagrams per year for 2015 to 2017 against their atmospheric estimate, the researchers derived an emitted fraction of only 11 to 25 percent, well below the previously assumed two thirds. (Same source.)
12. 0.7 to 1.7 teragrams of CO2 equivalent per year on a 100-year GWP basis, or 1.2 to 2.7 teragrams on a 20-year basis, for California in 2015 to 2017. (Same source.)
13. California’s own reductions averaged 2.25 teragrams per year from 2010 to 2015 under AB-32, having averaged 4.8 teragrams per year across 2007 to 2019. (Same source, citing California state reporting.)
14. Excluded from every inventory. Sulfuryl fluoride is not in the EPA Greenhouse Gas Reporting Program, not in the US National Greenhouse Gas Inventory, and was not included in the 2015 Paris Agreement. (Same source.)
15. California classified it as a short-lived climate pollutant in 2016 and has still not added it to the state’s annual greenhouse gas inventory or its Climate Change Scoping Plan. (Same source.)
16. Statewide California use was 1.575 gigagrams in 2022 and 1.393 in 2023, reported on 4,768 and 5,024 monthly use reports covering 109,837 and 97,052 applications respectively. (Author aggregation of California Department of Pesticide Regulation Pesticide Use Reports.)

What the gas actually is

In short: A fumigant that replaced an ozone-depleting one, has no ozone effect, and turned out to be a long-lived greenhouse gas instead.

Methyl bromide was the standard structural and commodity fumigant until it was identified as an ozone-depleting substance and largely phased out by 2005 under the Montreal Protocol, with exemptions for critical and quarantine uses. Sulfuryl fluoride was the non-ozone-depleting alternative, and its global use rose sharply as a direct consequence.

When sulfuryl fluoride was first approved as a pesticide in 1959, its atmospheric lifetime was thought to be negligible. Studies published in 2008 and 2009 established that it is removed from the atmosphere predominantly by ocean uptake and hydrolysis rather than by reaction in the air, which gives it an effective lifetime of 36 years. Its global warming potential was revised upward substantially as a result.

Sources: IPCC Sixth Assessment Report, Working Group I, Chapter 7 Supplementary Material, Table 7.SM.7, for lifetime, radiative efficiency and global warming potentials. Gaeta et al. 2024 for removal mechanism and current radiative forcing. Retrieved 27 September 2026.

What it means. A GWP of 4,630 means that a single 26-pound fumigation, the 2023 California structural average, carries the hundred-year warming equivalent of roughly 55 tonnes of carbon dioxide if all of the gas reached the atmosphere. It does not all reach the atmosphere, which is the subject of a later section, but the order of magnitude is why this compound attracts research attention.

What limits it. Global warming potential is a simplification that compresses a time-dependent radiative effect into one number, and the choice of horizon changes it by a factor of five here, from 7,510 at 20 years to 1,410 at 500. Anyone quoting a GWP must state the horizon. Radiative forcing from sulfuryl fluoride remains small in absolute terms at roughly 0.5 milliwatts per square metre.

Where the emissions are

In short: Atmospheric measurements and pesticide application records independently point at the same three Southern California counties.

The 2024 study used high-precision measurements from the NOAA Global Greenhouse Gas Reference Network collected across North America throughout 2015 to 2019, combined with a geostatistical inverse model and the STILT atmospheric transport model, to infer surface emissions. This is a top-down method: it works backwards from measured air concentrations to the emissions that must have produced them.

Source: Gaeta et al., “California dominates U.S. emissions of the pesticide and potent greenhouse gas sulfuryl fluoride”, Communications Earth & Environment 5:161 (2024). Global figure attributed in that paper to Gressent et al.

The study reports that the highest emissions come from southern coastal California, specifically Los Angeles, Orange and San Diego counties, and that outside California emissions are small and sparse.

What it means. Two completely independent methods agree. The atmospheric inversion identifies Los Angeles, Orange and San Diego as the hotspots. California’s pesticide application records, which we aggregated separately, put Los Angeles first at 25.5 percent of statewide sulfuryl fluoride pounds in 2023, San Diego second at 12.3 percent and Orange third at 10.3 percent. When a top-down measurement and a bottom-up administrative record converge on the same geography, both gain credibility.

What limits it. The authors are explicit that their monitoring network is not dense in the southeastern United States, where termite pressure is also high, so emissions there could be under-detected. They note there is no long-term network site in Florida that would help constrain emissions from that region. The uncertainty on the non-California estimate, plus or minus 0.16 against a central value of 0.05, is larger than the estimate itself.

Only a fraction of what is applied reaches the air

In short: Reconciling California’s reported use against the atmospheric estimate gives an emitted fraction of 11 to 25 percent, far below the two thirds previously assumed. Most applied sulfuryl fluoride is absorbed or destroyed rather than vented.

This is the most operationally interesting finding in the paper and it is good news relative to the prior assumption.

California is the only state that keeps a public record of statewide sulfuryl fluoride use, which is what makes the comparison possible at all. The researchers report that use rose from 0.976 gigagrams in 2007 to 1.367 gigagrams in 2018, with a mean of 1.435 gigagrams per year across 2015 to 2017. Their inverse model put actual emissions at 0.16 to 0.36 gigagrams per year over the same window.

Source: Gaeta et al. 2024. The emitted fraction is the authors’ calculation, stated in the paper as “equivalent to only 11-25% of the total reported SO2F2 use in 2015-2017 (assuming accurate SO2F2 usage data reporting to CDPR)”.

What it means. For structural fumigation, the portion of gas that is not absorbed onto surfaces or chemically destroyed during the fumigation escapes when the structure is aerated. An emitted fraction of 11 to 25 percent implies that most of the gas does not escape as sulfuryl fluoride. The paper notes a second consequence that cuts the other way: for commodity and agricultural fumigation, the absorbed fraction has implications for the fluoride and sulfate residues that end up in food.

What limits it. The authors state the assumption plainly, that reporting to the state is accurate. The two quantities also cover slightly different periods, use for 2015 to 2017 against emissions for 2015 to 2019. The ratio is an implied fraction derived from two independent estimates, each with its own uncertainty, not a measured emission factor from a controlled fumigation. A lower emitted fraction also means the applied-to-emitted relationship cannot be used to infer emissions in states without use reporting.

The inventory gap

In short: No greenhouse gas inventory counts this gas, and the quantity involved is comparable in scale to California’s measured climate progress.

Sulfuryl fluoride is absent from the EPA Greenhouse Gas Reporting Program, absent from the US National Greenhouse Gas Inventory, and was not included in the 2015 Paris Agreement. The IPCC identified it as a high-GWP gas in its Fifth Assessment Report in 2013. California’s Air Resources Board classified it as a short-lived climate pollutant in 2016 and, as of the 2024 paper, had not added it to the state’s annual greenhouse gas inventory or its Climate Change Scoping Plan.

The reason is chronological rather than political. California’s Global Warming Solutions Act, AB-32, passed in 2006. The long atmospheric lifetime of sulfuryl fluoride was not established until 2009. The gas was therefore not in scope when the accounting framework was written.

Source: Gaeta et al. 2024. One teragram equals one million metric tonnes. The authors describe the short-term warming effect of California’s sulfuryl fluoride emissions as “smaller yet comparable in scale to the annual statewide CO2e reductions achieved under AB-32”.

What it means. On a 20-year basis, an emissions stream that no inventory counts is of the same order as the reductions the state counts as its climate progress. The authors’ conclusion is that California could accelerate its reductions by including sulfuryl fluoride in inventories and either phasing out its use or mandating abatement of emissions. Abatement is technically possible: the search literature includes work on adsorption and recovery of sulfuryl fluoride from air, and spent fumigation gas is currently vented unfiltered.

What limits it, and it matters for fairness. Comparing an emissions figure on a 20-year GWP basis against a reductions figure computed on a 100-year basis is not an equivalent comparison, and the honest version uses the 100-year range of 0.7 to 1.7 teragrams against reductions of 2.25 to 4.8. On that basis the emissions are a third to three quarters of the reductions rather than comparable to or exceeding them. The paper reports both horizons; readers should quote whichever they use and say which it is.

Our extension of the use record

In short: The published use record stops at 2018. We extend it to 2023 and find two changes: total use is higher than the paper’s latest year, and the structural share of it has fallen.

The 2024 paper cites California use rising from 0.976 gigagrams in 2007 to 1.367 gigagrams in 2018. We aggregated the same state source for 2022 and 2023 across all site codes, not only structural.

Sources: 2007 and 2018 figures and the approximate shares as reported in Gaeta et al. 2024. 2022 and 2023 figures aggregated by the author from California Department of Pesticide Regulation Pesticide Use Reports, all site codes, chemical code 618, retrieved 27 September 2026. One gigagram equals 1,000 metric tonnes or 2,204,622 pounds.

What it means. Three observations follow. First, 2022 use of 1.575 gigagrams is higher than any year the paper cites, so the upward trend it describes did not stop at 2018. Second, 2023 fell back to 1.393 gigagrams, close to the 2018 level, so the series is not smoothly rising. Third, the structural share of statewide use has fallen from roughly 85 percent in the paper’s era to about 75 percent in 2022 and 2023, meaning commodity and other non-structural fumigation now accounts for a quarter of California’s sulfuryl fluoride. That shift matters for attribution: a smaller share of this climate liability belongs to structural pest control than the earlier figure implied.

What limits it. Two years is not a trend, and we did not compute statewide totals for the intervening years 2019 through 2021. The paper’s approximate 85 percent structural share and greater-than-50 percent county concentration are stated as approximations for an unspecified period, so the comparison against our precise 2022 and 2023 figures is indicative rather than a like-for-like change measurement. Applying the paper’s 11 to 25 percent emitted fraction to our 2023 figure of 1.393 gigagrams would give 0.15 to 0.35 gigagrams emitted, which falls inside the paper’s own estimate, but that is a consistency check rather than a new emissions estimate and we do not present it as one.

What operators should take from this

In short: Fumigation remains the only whole-structure treatment for drywood termites. The alternatives named in the literature do not replace it. The realistic policy risk is inventory inclusion and abatement requirements, not prohibition.

The paper is careful on this point, and so is this report. It lists the non-fumigation alternatives: localised wood replacement, wood injection with pesticides, heat treatment above 50 degrees Celsius, cold treatment with liquid nitrogen, electrocution and microwave radiation. It then states that these alternatives “generally do not provide whole-structure eradication of termites”. The authors call for development of sustainable, entomology-guided techniques, which is a research agenda rather than an available substitute.

Sulfuryl fluoride is separately regulated by EPA as a restricted-use pesticide because of its inhalation toxicity, and is currently undergoing re-registration review. Our coverage of restricted use pesticides explains what that classification means for who may apply it, and termite tenting and fumigation covers the treatment itself.

The practical reading. The three things a policymaker could do with this evidence are to add the gas to inventories, require emission abatement at the point of aeration, or restrict use. The first two are directly implied by the paper. Abatement technology exists in the literature. An operator planning capital expenditure on fumigation capacity over a ten-year horizon should treat abatement requirements as a live possibility in California specifically.

What we calculated from the published values

1. Warming equivalent per fumigation

Definition. The CO2-equivalent warming attributable to a single average structural fumigation, at a stated GWP horizon and emitted fraction.

Formula. CO2e per fumigation = mean pounds of active ingredient per fumigation ÷ 2,204.62 × emitted fraction × GWP.

Inputs. Mean 26.4 pounds per structural sulfuryl fluoride fumigation in California in 2023: 2,068,576 pounds on monthly use reports that state an application count, divided by the 78,398 fumigations those reports record. From our aggregation of state records. Emitted fraction 11 to 25 percent, from Gaeta et al. 2024. GWP 4,630 at 100 years and 7,510 at 20 years, from IPCC AR6.

Result. At the 100-year GWP, 6.1 to 13.9 tonnes of CO2 equivalent per fumigation. At the 20-year GWP, 9.9 to 22.5 tonnes. Without applying any emitted fraction, that is, if all applied gas reached the atmosphere, the 100-year figure would be 55.4 tonnes.

Limitations. The emitted fraction is a statewide implied average across structural and commodity use, not a per-fumigation measurement, and it is the dominant source of uncertainty. Mean pounds per application conceals a wide distribution driven by structure size. This figure should not be used for any individual job or for offset accounting.

2. Inventory exposure ratio

Definition. Unaccounted emissions from a single gas expressed as a share of a jurisdiction’s counted annual emissions reductions, as a measure of how much an inventory omission matters.

Formula. Exposure = unaccounted emissions in Tg CO2e per year ÷ counted reductions in Tg CO2e per year, at a matched GWP horizon.

Inputs. Gaeta et al. 2024, for both numerator ranges and both reduction averages.

Result. On the 100-year GWP, California’s sulfuryl fluoride emissions of 0.7 to 1.7 teragrams against reductions of 2.25 teragrams per year for 2010 to 2015 gives an exposure of 31 to 76 percent. Against the longer-run average of 4.8 teragrams, 15 to 35 percent.

Why it is framed this way. The paper compares its 20-year figure against reductions and calls the two comparable. We report the matched-horizon version because comparing a 20-year GWP quantity against reductions computed on a 100-year basis inflates the ratio. Both framings appear above so a reader can choose.

Limitations. California’s reported reductions and this emissions estimate cover overlapping but not identical periods. Reductions are a flow measured against a baseline while these emissions are an absolute flow, so the ratio is a rhetorical comparison rather than an accounting identity.

3. Top-down and bottom-up geographic concordance

Definition. Whether an atmospheric inversion and an independent administrative record identify the same emission hotspots, used as a mutual validation check.

Method. Compare the counties identified as highest-emitting by the inverse model against the counties ranked highest by reported pesticide application mass, for the same compound.

Inputs. Gaeta et al. 2024 for the inversion. Our aggregation of California Pesticide Use Report records, chemical code 618, for 2022 and 2023.

Result. The inversion names Los Angeles, Orange and San Diego counties. The application record ranks Los Angeles first in both years, at 19.9 percent of statewide pounds in 2022 and 25.5 percent in 2023, with San Diego and Orange in the top four in both years. The two methods agree on the leading county and on the cluster. They diverge on one point: Riverside County ranks third in the 2022 application record at 9.8 percent and is not named among the atmospheric hotspots.

Limitations. The comparison spans different periods, 2015 to 2019 for the inversion against 2022 and 2023 for the application record. Application location is the treated structure, while inferred emissions reflect where gas entered the atmosphere and how air moved, so exact correspondence is not expected. The inversion’s spatial resolution is coarser than a county.

Related: where in California structural fumigation happens is mapped county by county in where California tents its houses.

Related: eight years of fumigation volumes are in California is tenting fewer buildings.

Download the data

The tables in this report are published as CSV files under a Creative Commons Attribution 4.0 licence. You may republish, remix and build on them, including commercially, with attribution to The Pest Control Brief and a link to this page.

• Sulfuryl fluoride atmospheric properties and global warming potentials (CSV, 5 rows)
• California sulfuryl fluoride use, 2007 to 2023 (CSV, 4 rows)

Corrections

2 October 2026. An earlier version of this report divided sulfuryl fluoride pounds by the number of California use records and described the result, 549 pounds, as the average fumigation. California reports structural pest control as monthly summaries, and each record can cover many fumigations; the state records the number in a separate application-count field. Using that field, the 2023 structural average is 26.4 pounds per fumigation, and the warming equivalent per fumigation is 6.1 to 13.9 tonnes of CO2 equivalent on a 100-year basis, not 127 to 288. Statewide totals, emissions estimates and all other figures are unaffected.

How to cite this report

The Pest Control Brief, “Pest Control's Largest Chemical Is a Greenhouse Gas: The Sulfuryl Fluoride Evidence”, 2 October 2026. https://thepestcontrolbrief.com/sulfuryl-fluoride-greenhouse-gas/

References

1. Gaeta, D.C., Mühle, J., Vimont, I.J., Crotwell, M., Hu, L., Miller, J.B., McKain, K., Baier, B.C., Zhang, M., Bao, J., Miller, B.R. and Miller, S.M. (2024). “California dominates U.S. emissions of the pesticide and potent greenhouse gas sulfuryl fluoride.” Communications Earth and Environment 5:161. doi.org/10.1038/s43247-024-01294-x. Open access. Accessed 27 September 2026.
2. IPCC (2021). Sixth Assessment Report, Working Group I, Chapter 7 Supplementary Material, Table 7.SM.7. ipcc.ch, Chapter 7 Supplementary Material (PDF). Accessed 27 September 2026. Source for atmospheric lifetime, radiative efficiency and all three global warming potentials.
3. California Department of Pesticide Regulation. Pesticide Use Report annual archives for 2022 and 2023, chemical code 618. files.cdpr.ca.gov/pub/outgoing/pur_archives/. Accessed 27 September 2026. Source for the statewide use figures we add.
4. Gressent, A. and colleagues, as cited in Gaeta et al. 2024 for the global mean emissions estimate of approximately 2.89 gigagrams per year over 2015 to 2017.
5. NOAA Global Monitoring Laboratory, Global Greenhouse Gas Reference Network. Measurement network underpinning the emissions estimate in Gaeta et al. 2024. gml.noaa.gov.
6. US Environmental Protection Agency. Sulfuryl fluoride is a restricted-use pesticide and is under registration review; status as reported in Gaeta et al. 2024.

How this review was assembled

What this report is. Principally a summary of peer-reviewed findings that the pest control trade press has not covered, plus one original extension. We did not perform atmospheric modelling and make no independent emissions estimate.

Primary sources for the science. Global warming potentials, atmospheric lifetime and radiative efficiency come from the IPCC Sixth Assessment Report, Working Group I, Chapter 7 Supplementary Material, Table 7.SM.7, retrieved as a PDF from ipcc.ch on 27 September 2026. We verified our reading of that table against three compounds with independently known AR6 values before using the sulfuryl fluoride row: carbon tetrafluoride at a 100-year GWP of 7,380, Halon-1301 at 7,200 and methyl bromide at 2.43. All three matched the column we read as the 100-year GWP, which confirms the column mapping.

Primary source for emissions. Gaeta, D.C., Mühle, J., Vimont, I.J., Crotwell, M., Hu, L., Miller, J.B., McKain, K., Baier, B.C., Zhang, M., Bao, J., Miller, B.R. and Miller, S.M. (2024), “California dominates U.S. emissions of the pesticide and potent greenhouse gas sulfuryl fluoride”, Communications Earth and Environment, volume 5, article 161, doi 10.1038/s43247-024-01294-x. Retrieved as the publisher PDF on 27 September 2026. Their method is a geostatistical inverse model applied to NOAA Global Greenhouse Gas Reference Network measurements for 2015 to 2019, with STILT atmospheric transport.

Our original contribution. Statewide California sulfuryl fluoride use for 2022 and 2023, aggregated from California Department of Pesticide Regulation Pesticide Use Report annual archives, filtering on chemical code 618 across all site codes, with the structural portion identified as site code 10. Application counts are use-record counts. Pound-to-gigagram conversion uses 2,204.62 pounds per metric tonne.

What we attribute and what we derived. Every emissions figure, the emitted fraction of 11 to 25 percent, the CO2-equivalent ranges and the AB-32 reduction averages are the paper’s, not ours. The 2022 and 2023 use totals, application counts, structural shares and county shares are ours. The three quantities in Original Synthesis are ours, each built from the paper’s published values and our aggregation.

Limitations. The emissions estimates cover 2015 to 2019 and the use figures we add cover 2022 and 2023, so they are not contemporaneous. The monitoring network underpinning the emissions estimate is sparse in the southeastern United States, where the authors note termite pressure is also high, so non-California emissions may be underestimated. California is the only state publishing use data, so no equivalent reconciliation is possible elsewhere. Global warming potential is horizon-dependent and this report quotes three horizons for that reason. We did not verify the AB-32 reduction figures against California state publications independently and report them as cited in the paper. We did not contact the authors.

Last reviewed: 27 September 2026.

Evidence base

Tier 1, peer-reviewed and intergovernmental. Gaeta et al. 2024, Communications Earth and Environment 5:161. IPCC Sixth Assessment Report, Working Group I, Chapter 7 Supplementary Material. Gressent et al., cited within Gaeta et al. for the global emissions estimate of approximately 2.89 gigagrams per year over 2015 to 2017. NOAA Global Greenhouse Gas Reference Network measurements, as used in Gaeta et al.

Tier 1, primary government data. California Department of Pesticide Regulation, Pesticide Use Report annual archives for 2022 and 2023.

Tier 2, credible secondary. None of the figures in this report derives from a secondary source.

Excluded. Advocacy petitions concerning sulfuryl fluoride regulation were excluded as sources for any figure, because this report is about what the measurement literature establishes. Vendor material on fumigation was excluded. Any figure we could not trace to the IPCC table, the 2024 paper or the state use records was left out.

For reporters covering this

Most quotable statistics

1. Sulfuryl fluoride has a 100-year global warming potential of 4,630 and a 20-year potential of 7,510.
2. California produces 60 to 85 percent of all US sulfuryl fluoride emissions and 5.5 to 12 percent of global emissions.
3. Only 11 to 25 percent of the sulfuryl fluoride applied in California appears to reach the atmosphere.
4. The gas is in no US federal or California state greenhouse gas inventory, and California classified it as a short-lived climate pollutant in 2016.
5. California’s sulfuryl fluoride emissions are 0.7 to 1.7 teragrams of CO2 equivalent a year on a 100-year basis, against counted statewide reductions averaging 2.25 teragrams a year from 2010 to 2015.

Data limitations to quote alongside them

Emissions estimates cover 2015 to 2019 and rest on atmospheric inversion, not direct measurement of sources. The monitoring network is sparse in the southeastern United States, so non-California emissions may be underestimated. GWP depends on the horizon chosen and this compound’s values differ fivefold across horizons. The emitted fraction assumes accurate state use reporting. Fumigation remains the only whole-structure treatment for drywood termites.

Fields in the published CSV files

Year; jurisdiction; reported use in gigagrams; application count; structural share; inferred emissions in gigagrams; emitted fraction; GWP horizon; CO2 equivalent in teragrams; source.

Press summary

The single largest chemical by weight in California structural pest control is a greenhouse gas that no inventory counts, according to an analysis by The Pest Control Brief of peer-reviewed research and state pesticide records. Sulfuryl fluoride, used for whole-structure termite fumigation, has a 100-year global warming potential of 4,630 and an atmospheric lifetime of 36 years, per the IPCC Sixth Assessment Report. A 2024 study in Communications Earth and Environment found that California produces 60 to 85 percent of US emissions of the gas, at 0.26 gigagrams a year, and that Los Angeles, Orange and San Diego counties are the hotspots. The same study found that only 11 to 25 percent of applied sulfuryl fluoride reaches the atmosphere, far below the two thirds previously assumed. The gas is excluded from the EPA Greenhouse Gas Reporting Program, the US national inventory and the Paris Agreement, and California has not added it to the state inventory despite classifying it as a short-lived climate pollutant in 2016. The Pest Control Brief extends the state use record to 2023 and finds statewide use of 1.393 gigagrams, with the structural share down from roughly 85 percent to 74.6 percent.

Five headlines editors could use

1. Pest control’s biggest chemical by weight is a greenhouse gas nobody counts
2. California emits most of America’s sulfuryl fluoride, and no inventory records it
3. The termite gas with a warming potential of 4,630
4. Most of the fumigant applied never reaches the air, new research finds
5. An unintended consequence of saving the ozone layer

Reader questions

Is sulfuryl fluoride a greenhouse gas?

Yes. The IPCC Sixth Assessment Report gives it a 100-year global warming potential of 4,630 and an effective atmospheric lifetime of 36 years. It is not an ozone-depleting substance.

How much warming does one fumigation cause?

Applying the published emitted fraction of 11 to 25 percent to the 2023 California structural average of 26.4 pounds per fumigation gives roughly 6.1 to 13.9 tonnes of CO2 equivalent on a 100-year basis. That is our calculation from two published sources, not a measured value, and it should not be used for any individual job.

Which state emits the most?

California, by a wide margin. The 2024 study puts California at 60 to 85 percent of the US total, with emissions elsewhere small and infrequently detected.

Does all the fumigant end up in the atmosphere?

No. Reconciling California’s reported use against atmospheric measurements gives an emitted fraction of 11 to 25 percent, meaning most applied gas is absorbed onto surfaces or chemically destroyed during the fumigation.

Why is the gas not in any greenhouse gas inventory?

Largely timing. California’s climate law passed in 2006 and the long atmospheric lifetime of sulfuryl fluoride was not established until 2009, so it was not in scope. California classified it as a short-lived climate pollutant in 2016 but has not added it to the state inventory.

Is sulfuryl fluoride going to be banned?

Nothing in this research proposes a ban. The authors suggest including it in inventories and either phasing out use or mandating abatement of emissions. It is separately under EPA re-registration review as a restricted-use pesticide because of inhalation toxicity.

Are there alternatives to fumigation for drywood termites?

Several exist, including wood replacement, wood injection, heat above 50 degrees Celsius, liquid nitrogen, electrocution and microwave treatment. The 2024 paper states that these generally do not provide whole-structure eradication. See our coverage of termite tenting and fumigation.

Why did use of this gas increase?

Methyl bromide, the previous standard fumigant, was an ozone-depleting substance and was largely phased out by 2005 under the Montreal Protocol. Sulfuryl fluoride was the non-ozone-depleting replacement.

How much sulfuryl fluoride does California use?

1.575 gigagrams in 2022 and 1.393 gigagrams in 2023 across all uses, which is 3.47 and 3.07 million pounds. About three quarters of that was structural pest control. Those are our aggregations of state records.

Where can I read the research?

Gaeta et al., “California dominates U.S. emissions of the pesticide and potent greenhouse gas sulfuryl fluoride”, Communications Earth and Environment volume 5, article 161, 2024. It is open access. The global warming potentials are in the IPCC Sixth Assessment Report, Working Group I, Chapter 7 Supplementary Material.