DPR Releases Draft 2025 Annual Report on 1,3-D, Opens Public Comment Period
The California Department of Pesticide Regulation (DPR) has released its draft 1,3-Dichloropropene (1,3-D) report for 2025. A 45-day comment period is open for this draft report through November 30, 2026.
Regulations that went into effect in 2024 require lower‑emission fumigation methods, setback distances between treated fields and occupied structures, limited application rates and acreage, and higher soil moisture levels during fumigation to reduce 1,3-D air concentrations.
Under the regulation, DPR must issue an annual report assessing statewide 1,3‑D use and air monitoring results from the previous calendar year. Annual 1,3-D reports include an evaluation of high-use townships and monitoring locations with an average air concentration of more than 0.27 parts per billion (ppb) in the previous calendar year or an air concentration of more than 55 ppb for a 24-hour period.
On September 30, 2026, the California Department of Food and Agriculture (CDFA) Center for Analytical Chemistry, who provides the independent lab analysis for DPR’s air monitoring program, officially notified DPR that it was recalling and voiding about nine months of 1,3-D data due to significant degradation of a laboratory reference standard. Specific to 2025 data, 1,3-D air samples analyzed from October 24 through December 31, 2025 were recalled and voided by CDFA. DPR has not included affected data in the Draft 2025 1,3-D Report. However, as explained in the report, the department has elected to evaluate all six air monitoring stations using modeling tools. An evaluation of the Parlier monitoring station, which DPR initiated prior to receiving the CDFA notification, is included in this version of the Draft 2025 1,3-D Report. DPR intends to conduct further evaluation of the remaining five monitoring locations to be released as an update as soon as feasible.
Submit a Public Comment
DPR has opened a 45-day public comment period through November 30, 2026, to collect feedback on the Draft 2025 Annual 1,3-D report. Comments can be submitted online through DPR’s SmartComment portal.
2025 Air Monitoring Reports
DPR is finalizing several 2025 reports impacted by the CDFA recall and void of 2025 data. The department prioritized today’s release of the draft 1,3-D Annual Report. DPR intends to issue two additional reports – the 2025 Air Monitoring Network (AMN) Report and the Study 309 Report – by October 23, 2026. The AMN report will include results for 38 pesticides and degradants for 2025 and 9 months of data for 1,3-D and methyl bromide that was not impacted by the CDFA recall. The 309 study report will include 9 months of data for 1,3-D for two air monitoring stations in Parlier and Delhi.