12.5 Category 6: Fumigation & Fumigation Management Plans
Key Takeaways
- Category 6 covers non-soil fumigation — the use of restricted use pesticides to fumigate anything other than soil — and it is the highest-hazard structural category because fumigants are non-selective gases with no residual warning.
- Fumigation requires immediate supervision under A.A.C. R3-8-401, meaning a physically present certified applicator supervising no more than two uncertified applicators at a time.
- A written Fumigation Management Plan is required by fumigant labels and must be completed before the fumigant is introduced, covering site characterisation, monitoring, sealing, placarding, aeration and emergency response.
- Air-purifying respirators do not protect against fumigants: sulfuryl fluoride, methyl bromide and phosphine require self-contained breathing apparatus or supplied air, with clearance determined by instrument monitoring and never by smell.
Category 6: Fumigation & Fumigation Management Plans
Core Principle: A fumigant is a gas that fills a space and kills essentially anything that breathes in it. There is no droplet to see, no residue to feel, and — for the most dangerous of them — no reliable smell. Everything that makes fumigation effective also makes it the one pest control activity that routinely kills applicators and bystanders when procedure slips.
Scope and Jurisdiction
Category 6 — Non-soil fumigation applies to commercial applicators who use or supervise the use of a restricted use pesticide to fumigate anything other than soil.
Arizona splits fumigant jurisdiction, and the split is examinable:
| Situation | Where it lands |
|---|---|
| Fumigating for others | PMD certification and licensure |
| On your own farm, raw agricultural commodities or burrowing rodents | Agricultural Private Fumigation category |
| On your own farm, any fumigant other than agricultural soil fumigants, raw commodities or burrowing rodents | PMD certification and licensure |
Golf applicators, notably, take non-soil fumigation as one of their three continuing education alignments.
The Major Fumigants
| Fumigant | Characteristics and hazards |
|---|---|
| Sulfuryl fluoride | The dominant structural fumigant for drywood termites. Odourless and colourless — a chloropicrin warning agent is introduced first to force evacuation and detect leaks. Requires clearance by instrument. |
| Methyl bromide | Odourless at working concentrations, highly toxic, and severely restricted as an ozone-depleting substance under the Montreal Protocol; use is limited to specific exemptions. Also uses a chloropicrin warning agent. |
| Phosphine (aluminium or magnesium phosphide) | Generated when the metal phosphide reacts with atmospheric moisture. Used for stored commodities and burrowing rodents. Water contact can cause ignition, and spent residue is reactive; it demands strict handling and disposal procedure. |
| Chloropicrin | Severe lachrymator used as a warning agent, and a fumigant in its own right. Its value is precisely that it is intolerable at concentrations far below dangerous ones. |
The Fumigation Management Plan
Fumigant labels require a written Fumigation Management Plan (FMP), completed before the fumigant is introduced. It is not paperwork generated afterwards. A complete FMP addresses:
- Site characterisation — construction type, volume, adjoining and attached structures, shared walls, HVAC and utility penetrations, sewers and drains.
- Occupancy — who must be evacuated, including adjoining units in multi-family construction; verification that the structure is clear before introduction.
- Sealing — tarpaulins, taping, sand snakes, and the method of securing them against Arizona wind.
- Warning agent — where required, introduced before the fumigant and verified.
- Placarding and security — warning signs at every entrance with the fumigant name, the date and time of introduction, and contact information; continuous security so nobody enters.
- Monitoring — instruments, detection method, who monitors and when, including the perimeter during exposure.
- Dosage and exposure period — calculated from volume, temperature and target pest.
- Aeration plan — the sequence and duration for ventilating the structure.
- Clearance — the instrument-measured concentration that permits re-entry, and who determines it.
- Emergency response — the emergency contacts, the nearest medical facility, and the procedure if a leak, injury or unauthorised entry occurs.
Respiratory Protection: The Rule That Kills People When Ignored
Air-purifying respirators do not protect against fumigants. A cartridge respirator is designed to adsorb vapours at concentrations far below fumigant working levels, and it offers no oxygen. Fumigation requires self-contained breathing apparatus (SCBA) or a supplied-air respirator, used by trained personnel.
Equally: smell is not a clearance method. Sulfuryl fluoride and methyl bromide are odourless at hazardous concentrations, which is exactly why a warning agent is used. Re-entry is authorised by an instrument reading at or below the label’s clearance concentration, taken in the breathing zone throughout the structure — not by the absence of odour and not by elapsed time alone.
Supervision and Personnel
Fumigation is listed in A.A.C. R3-8-401(D) as requiring immediate supervision: a certified applicator physically present, supervising not more than two uncertified applicators at a time. Given the hazard, this is the least negotiable supervision requirement in the Arizona rules.
The Sequence
- Plan and characterise — complete the FMP.
- Notify and evacuate — occupants, neighbours where the structure is attached, and any party the label or the FMP identifies.
- Seal — tarp and seal, secure against wind.
- Placard and secure — signs at every entrance; maintain security for the whole exposure period.
- Introduce the warning agent, where required, and confirm the structure is clear.
- Introduce the fumigant at the calculated dosage.
- Monitor through the exposure period, including the perimeter.
- Aerate per the plan.
- Clear by instrument — measure, record, and only then authorise re-entry.
- Document and report — records under A.A.C. Title 3 Chapter 8 Article 5; where the job is a structural termite treatment, the TARF obligations of R3-8-503(D) apply.
Exam Trap: the two errors that recur in fumigation questions are wearing an air-purifying respirator into a fumigated space, and clearing a structure by time or smell rather than by instrument. Both are fatal in practice and always wrong on the exam.
A crew is preparing to enter a structure that has just been aerated after a sulfuryl fluoride fumigation. Which basis for authorising re-entry is acceptable?
Why is an organic vapour cartridge respirator unsuitable for entry into a space under active fumigation?
A pest management company is fumigating an attached townhouse for drywood termites. When must the Fumigation Management Plan be completed?
Aluminium phosphide is being used to fumigate stored grain. Which handling hazard is specific to this fumigant?
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