A 3 ppm Reading at the Door and a Downed Technician
Two technicians are aerating a 6,000 ft3 single-family house at 6:40 a.m. after a sulfuryl fluoride fumigation. Technician R holds a detector at the open front door, reads 3 ppm, and says, 'That's under the PEL -- I'm just going to pop the windows.' He walks into the hallway with no respiratory protection to open the rear sliding door. Twenty seconds later technician M, standing at the truck, hears a crash and sees R unresponsive on the hallway floor about 18 ft inside. The blower is still running at the front door. The truck, 40 ft away, carries one SCBA and two spare cylinders. The nearest fire station is six minutes out. A neighbor is on the sidewalk filming.
1. List technician M's actions in priority order for the first six minutes, with the reason for each.
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- Do not enter bare-faced. An unprotected rescue into a fumigant atmosphere produces a second casualty and removes the only person who can get help. This is the single decision the scenario is testing.
- Call 911 and give the dispatcher the chemistry: 'Sulfuryl fluoride fumigant exposure, one unresponsive adult inside a tarped/aerating structure, entry requires SCBA.' Apparatus must not stage in the off-gas plume.
- Keep the blowers running and strip more tarp from outside. This is the fastest way to lower the concentration at and near the doorway, and it can be done without entering.
- Shout to R and keep verbal contact; noise and airflow may rouse him enough to crawl toward the light.
- Don the SCBA only if a second trained person is present to act as backup, then enter on a line. Never enter alone on air -- a single SCBA wearer with no backup becomes the next victim if the regulator or mask fails.
- On extraction: move to fresh air, oxygen if trained, never leave the patient unattended, and hand the fire/EMS crew the product name, SDS, and your monitoring readings.
- Control the scene: keep the neighbor and any bystanders outside the perimeter; the video will be evidence, so leave the area undisturbed once it is safe.
2. Explain why the 3 ppm door reading did not make the entry safe, addressing both the toxicology and the sampling logic.
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The reading measured the wrong thing. A detector held in the open doorway during active aeration measures dilution air, not the atmosphere 18 ft inside. Concentrations in a structure being ventilated form steep gradients; a door reading is essentially an outdoor reading.
The PEL is the wrong yardstick. The 5 ppm PEL for sulfuryl fluoride is an 8-hour time-weighted average for a working shift, not a short-term entry permit. It does not authorize a few breaths in a space that has not been cleared, and it says nothing about the excursion concentration that produced unconsciousness within seconds.
Physical behavior. Sulfuryl fluoride is about 3.5 times as dense as air and pools in low areas and dead-air spaces such as hallways, closets, and crawlspaces -- exactly where R went.
Label rule. Entry into a structure under fumigation or under aeration before clearance is prohibited without supplied-air or SCBA, regardless of what a single reading shows. One point, one moment, no calibration check, and no clearance test is not clearance.
3. What must be reported and documented after the incident, and what information must accompany R to the emergency room?
Read the worked answer
To the treating physician, immediately: product name and active ingredient (sulfuryl fluoride), the label and SDS, the concentration recorded at the door, the estimated time inside (seconds to a minute or two before collapse), the time of collapse and of extraction, whether oxygen was administered, and the fact that the space was still under aeration.
To the employer: an immediate incident report; preserve the detector and its data log, the tarp condition, and the crew's PPE records.
To the regulator: this is a serious injury and triggers prompt reporting to Cal/OSHA -- within the required window for a fatality (8 hours) and for an inpatient hospitalization (24 hours). The structural pest control licensing authority also requires incident reporting; the licensed fumer in charge is the responsible party.
Internally: a written review of why the entry happened -- the real root cause is usually a crew norm that treats door readings as permission, plus the absence of a two-person entry rule and of a documented clearance procedure. Corrective action, retraining, and the disciplinary record belong in the file. Do not rewrite the timeline after the fact.