Sulfuryl Fluoride Clearance Devices
Introduction to Clearance Devices
Sulfuryl fluoride is the only fumigant currently registered for residential use. This involves placing a tarp or tent over the home, which could include multi-unit residences, to trap gas inside and then filling the structure with sulfuryl fluoride gas. After the treatment phase, a process referred to as “aeration” occurs to release the chemical from the structure.
Since sulfuryl fluoride is odorless and colorless and there is no way to know if a person has been exposed, to confirm the structure is safe to re-enter, the level of sulfuryl fluoride inside the structure must be under 1 part per million (ppm). A structure is considered “cleared” after the certified operator or someone under their supervision has verified the fumigant has adequately dissipated, as is indicated by a reading of 1 ppm or less in the breathing zones of each room using portable clearance devices (also referred to as gas analyzers). Breathing zones are areas within the structure where individuals typically stand, sit, or lie down.
According to current labels, clearance devices are intended to give immediate readings and respiratory protection is not required when clearing with these devices after having completed the initial one-hour active aeration procedure and when the reading indicates 1 ppm or less. If the device indicates levels in excess of 1 ppm, workers are to leave the affected area immediately until the measured level reaches 1 ppm or below. After the one-hour active aeration period whereby fans are used to circulate air and all operable windows and doors are open, there is a period of passive aeration from 6-8 hours. The certified operator is responsible for posting clearance notices at all entry points and notifying the resident that the home has reached the clearance level of 1 ppm, which has been determined by the Agency as “clear” or safe to reenter.
For EPA’s guidance on how to test clearance devices and submit data to EPA, please review Guidance on Sulfuryl Fluoride Clearance Device Testing.
Office of Inspector General Report
The Revised Mitigation and Response to Comment on the Draft Interim Re-Entry Mitigation Measures decision document is in response to the EPA Office of the Inspector General’s (OIG) published report entitled Additional Measures Can Be Taken to Prevent Deaths and Serious Injuries From Residential Fumigations. The OIG conducted this investigation to determine the extent and nature of adverse impacts caused by structural fumigation, after two incidents in 2015, including one with the chemical sulfuryl fluoride. This incident occurred in Florida, when members of a family fell ill after the family home in Palm City was fumigated using sulfuryl fluoride. The family returned to the home two days after it had been cleared for re-entry.
Clearance Device Effectiveness
The OIG report recommended that the Agency conduct an assessment of clearance devices to validate their effectiveness in detecting required clearance levels as part of the Office of Pesticide Programs’ ongoing re-evaluation of structural fumigants. In response to this recommendation, the Agency assessed the effectiveness of four commercially available clearance device models for detecting sulfuryl fluoride at the current labeled clearance level. The Agency has summarized the Laboratory Testing of Portable Clearance Devices with Sulfuryl Fluoride Standard, Analytical Chemistry Branch (ACB) below. For more details, please see the full report, which is available in EPA’s public docket (EPA-HQ-OPP-2009-0136) at www.regulations.gov.
Based on the results of laboratory testing, the Agency determined performance criteria for the clearance devices. A device is considered effective if the device detects sulfuryl fluoride at 1 part per million (ppm) reliably and accurately. For EPA’s guidance on how to test clearance devices and submit data to EPA, please review Guidance on Sulfuryl Fluoride Clearance Device Testing.
The Agency’s clearance device testing conclusions are summarized below. Results are published in Laboratory Testing of Portable Clearance Devices with Sulfuryl Fluoride Standard – All Devices. Final Report, Analytical Chemistry Branch (ACB), Office of Pesticide Programs, U.S. EPA. This report is available in EPA’s public docket EPA-HQ-OPP-2009-0136.
The Agency does not approve use of, or otherwise regulate the use of, specific clearance devices but has conducted testing on the effectiveness of some models of clearance devices in detecting required clearance levels in order to inform users.
Performance Criteria for Effective Devices
EPA considers a portable clearance device effective if it meets the following performance criteria:
- Reliability - Reliability is determined by the number of False Negatives (FN). The lower the number of false negatives, the more reliable the device. FNs are quantified by the percent of readings giving 0 ppm when measuring a standard with a nominal concentration of ppm. To be considered reliable, the rate of FN must be less than 30% with repeated readings over time.
- Accuracy - Accuracy is quantified by the percent of readings giving 1 ppm when measuring the 1 ppm standard. To be considered accurate, the percent of readings of 1 ppm when measuring a ppm standard repeatedly must be greater than 70%.
- Device calibration - All devices must be calibrated and re-calibrated per manufacturer’s specifications. Devices must be re-calibrated within the re-calibration interval. The Agency recommends that calibrations and re-calibrations include the clearance level of ppm.
- Device sensitivity - Most current devices claim sensitivity of ±0.5 ppm, which may impact the accuracy at 1 ppm, especially when the displayed reading is at a ppm interval (i.e., reading either 0 ppm or 1 ppm and nothing in between). The devices must be able to differentiate sulfuryl fluoride concentrations of 0.5 ppm and read at 0.5 ppm interval at the minimum and not only read in whole units.
Effective Devices
- M.A.C 2640 CLIRCheck (Manufacturer: ppm Messtechnik GmbH)*
|
Using ambient air as zeroing |
|
|---|---|
|
Reliability at 1 ppm (must be 30% or below to be considered reliable) |
Accuracy at 1 ppm (must be 70% or above to be considered accurate) |
|
11% |
70% |
- FumiSpec-Lo (Manufacturer: Uniphos Envirotronic)*
|
Using ambient air and dry air as zeroing |
|
|---|---|
|
Reliability at 1 ppm (must be 30% or below to be considered reliable) |
Accuracy at 1 ppm (must be 70% or above to be considered accurate) |
|
20% |
80% |
Not Effective Devices
- SF-ExplorIR (Manufacturer: Spectros Instruments)*
|
Using ambient air and dry air as zeroing air |
Using ambient air as zeroing air |
||
|---|---|---|---|
|
Reliability at 1 ppm (must be 30% or below to be considered reliable) |
Accuracy at 1 ppm (must be 70% or above to be considered accurate) |
Reliability at 1 ppm (must be 30% or below to be considered reliable) |
Accuracy at 1 ppm (must be 70% or above to be considered accurate) |
|
38-100% |
< 20% |
100% |
0% |
- GF1900 (Manufacturer: Interscan Corporation)*
|
Using ambient air as zeroing air |
Using dry air as zeroing air |
||
|---|---|---|---|
|
Reliability at 1 ppm (must be 30% or below to be considered reliable) |
Accuracy at 1 ppm (must be 70% or above to be considered accurate) |
Reliability at 1 ppm (must be 30% or below to be considered reliable) |
Accuracy at 1 ppm (must be 70% or above to be considered accurate) |
|
80% |
7% |
20% |
37% |
*Studies were performed by the EPA Biological and Economics Analysis Division Analytical Chemistry Branch lab.