FL Fumigation cheat sheet

Fumigants are toxic gases or vaporizing liquids that enter the target organism through the respiratory system; efficacy depends on gas concentration × exposure time (CT product), not concentration alone.

Common structural fumigants: methyl bromide (odorless, nonflammable, high ozone-depleting potential), sulfuryl fluoride (odorless, nonflammable, denser than air), phosphine (from metal phosphide, spontaneously flammable above ~1.8% in air, garlic-like odor from impurities), chloropicrin (lacrimatory warning agent and standalone fumigant).

Vapor density relative to air governs stratification: sulfuryl fluoride (≈3.5) and methyl bromide (≈3.3) sink and accumulate in low areas, basements, and subfloor voids; ventilation openings must therefore be placed low.

Flammability limits: methyl bromide is nonflammable in air but forms flammable mixtures with oxygen at elevated concentrations; phosphine ignites spontaneously at concentrations above about 1.8% v/v; never confine phosphine in unvented containers.

Label elements to extract before every job: active ingredient and concentration, signal word, PPE requirements, restricted-entry intervals, buffer zone tables, application rate ranges, aeration/clearance criteria, and required respiratory protection type.

SDS Section 8 gives exposure limits (e.g., methyl bromide OSHA PEL 20 ppm TWA; sulfuryl fluoride OSHA PEL 5 ppm TWA, ACGIH TLV 5 ppm TWA); Section 2 gives hazard classification; Section 4 gives first aid; Section 6 gives spill procedures.

Odor is not a reliable warning: methyl bromide and sulfuryl fluoride are essentially odorless, and olfactory fatigue occurs; use calibrated detection devices (thermal conductivity, electrochemical, colorimetric tubes) matched to the fumigant.

Chloropicrin is added as a warning agent at low percentages; its tear-gas effect is detectable well below hazardous fumigant concentrations, but it is itself toxic and irritating and does not replace monitoring.

Fumigation is a restricted-use activity; in Florida, structural fumigation for pests such as drywood termites requires a licensed fumigation category (commercial certified applicator) and supervision of noncertified applicators.

Federal framework: FIFRA governs label-as-law status - use inconsistent with the label is a violation; 40 CFR Part 156 covers labeling; 29 CFR 1910.120 (HAZWOPER) and 1910.134 (respiratory protection) apply to handlers; 49 CFR applies to transport of fumigant cylinders and metal phosphide.

Florida-specific: FDACS regulates pesticide applicators and dealers; fumigation notices must be posted on all entrances of the structure before introduction of gas and remain until clearance; notice content (fumigant, applicator name/firm, date, 24-hour contact) is specified by rule.

Required records typically include: site diagram, sealed-structure documentation, fumigant lot numbers and weights/cylinders used, calculated dosage and volume, introduction and aeration times, monitoring readings, clearance readings, persons on site, and signatures.

Fumigation management plan (FMP) is required by many fumigant labels; it documents target pest, structure volume, sealing method, dosage, monitoring, safety plan, and emergency contacts, and must be available on site.

Buffer zones: perimeter distances are calculated from label tables based on application rate, structure size/footprint, and structure type; buffer zones must be cleared of people and posted before introduction.

Notification requirements: occupants must be notified and vacate; adjacent units in attached structures (duplexes, townhomes) require notification and often evacuation; the applicator must verify no occupants remain before sealing.

Record retention: pesticide application records are generally kept for at least 2 years under federal rules and longer under some state rules; fumigation records must be available to regulators on request.

Fumigation targets pests in inaccessible voids and whole structures: drywood termites (family Kalotermitidae), wood-boring beetles (anobiid, bostrichid, cerambycid), and occasionally bed bugs, stored-product pests, and rodents.

Drywood termites live entirely within wood, produce kick-out holes with distinctive fecal pellets (six-sided, ~1 mm), and colonies are small; whole-structure fumigation is the standard curative approach for multi-colony or inaccessible infestations.

Dampwood termites and subterranean termites require moisture contact with soil; fumigation kills the in-structure population but does not remove the soil colony, so subterranean infestations need soil treatment instead.

Stored-product pests (e.g., Indian meal moth, flour beetles, cigarette beetle) are often treated with phosphine or methyl bromide in chambers, mills, or commodities; phosphine is favored where long exposure is possible and metal corrosion is a concern.

Life stages differ in susceptibility: eggs of many insects are more tolerant of fumigants than larvae/adults, so dosage must be set to kill the most tolerant stage present; phosphine is notably slow-acting and requires long exposure for egg kill.

Fumigant selection factors: target pest and life stage, temperature (fumigants are more effective and volatilize faster when warm), commodity/wood moisture, structure tightness, corrosion risk to metals and electronics, and label-approved uses.

Sulfuryl fluoride is effective against all termite castes and wood-boring beetles and penetrates wood well; methyl bromide is highly penetrative and fast but is being phased out for most non-quarantine uses under the Montreal Protocol.

Rodent burrow fumigation uses aluminum or magnesium phosphide tablets or gas cartridges; efficacy requires confirming active burrows and favorable soil moisture, and nontarget/endangered species restrictions apply.

Calculate structure volume from exterior dimensions (length × width × height) including attics, crawlspaces, subfloor voids, and attached garages when connected by air; measure rather than estimate, and document on a diagram.

Identify and plan for connected spaces: shared attics, plumbing chases, HVAC ducts, elevator shafts, and common walls in attached units; these determine whether adjacent units must be included in the treated volume or sealed off.

Pre-inspection checklist: confirm target pest and infestation extent, check for occupants/pets/plants, identify ignition sources, gas appliances, and pilot lights to be shut off, and locate any occupants requiring special assistance.

Assess structure condition: loose windows, deteriorated weatherstripping, unsealed penetrations, and open chimneys are sealing liabilities; note them and plan corrective sealing before introduction.

Utility and safety coordination: notify the local fire department where required, arrange for gas/electric service considerations, disable or tag HVAC systems, and confirm that smoke/CO detectors and alarm systems are addressed per label and local rule.

Buffer zone planning: determine required perimeter distance from label tables, identify neighboring structures, sidewalks, and public ways within it, and plan posting and occupant notification for those areas.

Weather and site factors: wind affects tarp security and gas loss, ambient temperature affects dosage and volatilization, and rain can compromise sealing; plan introduction timing and monitoring frequency accordingly.

Document the plan as a fumigation management plan: dosage calculation, fumigant quantity, sealing method, monitoring points and schedule, aeration plan, clearance criteria, and emergency contacts.

Sealing must make the structure gas-tight enough to hold concentration; common methods are taping/sealing windows and doors, sealing vents and penetrations, and full tarping of the structure with gas-proof tarps.

Tarp selection and installation: use fumigation-grade tarps sized to cover the roof and walls with overlap; secure with sand snakes, clamps, and ropes; sand-snake the roof perimeter and seal the tarp-to-ground junction to limit leakage.

Interior preparation: remove or protect food, feed, medications, and perishables; bag and remove or double-bag items that cannot leave; remove plants and pets; open interior doors and cabinet doors to allow gas distribution.

Ignition and appliance control: shut off pilot lights and gas appliances, unplug or protect sensitive electronics where label requires, and disable HVAC/air handlers so gas is not distributed to untreated spaces or exhausted prematurely.

Attached structures: seal common walls, shared attics, and utility chases, or include adjacent units in the treated volume and notify/evacuate them; never assume a shared attic is gas-tight.

Pre-introduction verification: walk the perimeter checking for open windows, unlocked doors, unsealed vents, and tarp gaps; confirm all occupants are out and post warning signs at every entrance before releasing gas.

Monitoring during fumigation: place monitoring lines at high and low points and in remote or hard-to-reach voids; use a gas analyzer to verify target concentration and detect leaks, and check the tarp perimeter and adjacent spaces for leakage.

Leak response during the hold: if concentration falls below target or a leak is detected, extend exposure, add fumigant, or reseal per label; document all corrections and readings.

Dosage basis: label rates are expressed per 1,000 cubic feet (or per 1,000 ft³ at a specified temperature); total fumigant = (structure volume ÷ 1,000) × label rate, adjusted for temperature and, where allowed, for leakage/tarping factors.

Example calculation: a 30,000 ft³ structure at a label rate of 1 lb per 1,000 ft³ requires 30 lb of fumigant; verify against cylinder weight loss and record actual amount introduced.

Temperature correction: many labels specify higher dosage below a threshold temperature (e.g., below 50–60 °F) because of reduced volatilization and insect activity; read the specific label table rather than extrapolating.

Introduction methods: methyl bromide and sulfuryl fluoride are released as gas or vapor from pressurized cylinders through a manifold and tubing into the structure, often with a vaporizer or warm-water bath for high-release rates; phosphine is generated from tablets/pellets or released from cylinders.

Release rate and distribution: introduce at a controlled rate to avoid pooling, use fans for mixing where label permits, and place discharge points to reach voids; sulfuryl fluoride and methyl bromide are heavier than air, so introduce high and monitor low points.

Sealing and leak factor: labels may allow reduced dosage for well-sealed/tarped structures or require increased dosage for leaky ones; do not apply reduced rates without documented tightness verification.

Phosphine application: tablets/pellets release gas on exposure to atmospheric moisture; never stack or pile them, place in shallow trays or on paper, and never confine in sealed containers or allow contact with water in a closed space.

Verification: after introduction, measure concentration at monitoring points, confirm it meets or exceeds the label target for the exposure period, and record the CT (concentration × time) achieved.

Aeration begins only after the required exposure period is complete; open the structure systematically from the top down and from the far end toward the exit, and remove tarps/seals to allow cross-ventilation.

Mechanical ventilation with fans accelerates clearance; direct exhaust away from occupied areas and neighboring structures, and keep the buffer zone posted until clearance readings are below the label clearance level.

Clearance criteria: the label specifies a maximum allowable concentration (e.g., sulfuryl fluoride 1 ppm or 3 ppm depending on label; methyl bromide 1 ppm or lower) that must be confirmed by a calibrated detector before re-entry without PPE.

Detection methods: use the instrument specified or approved for the fumigant (e.g., thermal conductivity or electrochemical analyzers, colorimetric detector tubes); calibrate before use and check zero in clean air.

Clearance sampling locations: test the lowest points, basements, crawlspaces, closets, cabinets, and any space where gas may have pooled; do not rely on a single reading at the entry.

Re-entry sequence: after clearance is confirmed, remove posting, ventilate remaining spaces, and allow occupants to return only when the label's re-entry criteria are met; document the clearance readings and time.

Aerating commodities and contents: porous materials (wood, fabrics, mattresses) can retain fumigant and re-release it; where labels require, aerate contents separately and verify with detector readings before use.

Post-fumigation documentation: record aeration start/end times, clearance readings and locations, instrument used and calibration, and the time posting was removed.

Evacuate and isolate: on a leak or spill, evacuate the area, establish control zones, keep people upwind, and deny entry; call emergency responders and the fumigant manufacturer's emergency number listed on the label/SDS.

Cylinder leaks: for a leaking cylinder, if safe to do so, close the valve, move the cylinder outdoors to a well-ventilated area, and keep it upright; do not attempt to stop a leak with tools that could ignite phosphine or damage the valve.

Metal phosphide spills: never use water or acid on spilled aluminum/magnesium phosphide - it liberates phosphine and can ignite; smother or cover with dry sand/earth, collect with nonsparking tools, and place in a vented container outdoors.

Phosphine fire: phosphine can reignite; use water fog to disperse gas and cool containers, and do not use dry chemical or CO2 as the primary agent for a phosphine-involved fire; evacuate and let responders handle it.

Respiratory protection: use only NIOSH-approved respirators with the correct canister/cartridge for the fumigant (e.g., supplied-air or SCBA for high concentrations and unknown atmospheres); escape-only respirators are not for entry into IDLH atmospheres.

First aid - inhalation: move the person to fresh air, call 911, keep them quiet and warm; give oxygen if trained and the person is breathing; do not use mouth-to-mouth if the victim's exposure is unknown - use a barrier device.

First aid - skin/eye contact with fumigant liquids or phosphine-generating products: flush eyes with water for at least 15 minutes, wash skin with soap and water, remove contaminated clothing, and get medical attention; chloropicrin causes severe irritation and requires prompt decontamination.

Post-incident: account for all personnel, do not re-enter until monitoring confirms safe levels, preserve records and readings, and report the incident as required by label and state rules.