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newSchoolWorks.com › VoTechWorks › Agriculture, Environment & Public Service › Pest Control Technician › Structural Fumigation Basics › Lesson 3
AGR-PEST78-05 · Lesson 3 · 6 clock hours · lab

Respiratory Protection and Personal Protective Equipment for Fumigation

Objective. Students will correctly don, seal-check, use, and doff a self-contained breathing apparatus (SCBA) and demonstrate understanding of when each class of respiratory protection is required under fumigation label and OSHA standards.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a licensed professional in the field or by a certification or approval body. It is a study draft and may contain errors. Do not use it as instructions for work on a job site or on live equipment. Always follow your instructor, your supervising professional, and current official references and regulations.

VoTechWorks program approval and accreditation are still in progress. Credentials are issued only by the certifying bodies named in each program, after their own exams.

Why Respiratory Protection Is the Top Priority in Fumigation

Fumigants such as methyl bromide and phosphine are acutely toxic gases. Exposure to even brief concentrations above the permissible exposure limit (PEL) can cause serious injury or death. Because these gases are invisible and often odorless at dangerous concentrations, you cannot rely on your senses to warn you. Your respiratory protection system is your primary defense against a life-threatening hazard every time you work near or inside a treated structure.

Fumigation is one of the few agricultural and structural pest control tasks where OSHA's respiratory protection standard, 29 CFR 1910.134, and the fumigant product label both impose mandatory, specific equipment requirements. The label is a legal document under FIFRA. Following it is not optional.

Classes of Respiratory Protection Used in Fumigation

Self-Contained Breathing Apparatus (SCBA) supplies its own air from a compressed-air cylinder carried by the wearer. It provides the highest level of protection and is required any time you enter a structure that has been sealed and gassed, or any time atmospheric concentration is unknown. SCBA units used in fumigation must be NIOSH-approved and are classified as atmosphere-supplying respirators. They operate in either open-circuit (exhaled air vented to atmosphere) or closed-circuit (air recycled) mode; open-circuit units are standard in structural fumigation.

Supplied-Air Respirators (SAR), also called airline respirators, deliver air through a hose from a remote compressor or cylinder bank. They are used in some fumigation support roles where mobility is limited and continuous air supply from a stationary source is acceptable.

Air-Purifying Respirators (APR), including half-face and full-face units fitted with appropriate cartridges, remove contaminants by filtering ambient air. They require oxygen concentrations of at least 19.5 percent to be safe. APRs are never acceptable inside a sealed, gassed structure. They may be appropriate during certain outdoor tasks—always check the specific fumigant label for the exact cartridge type and permissible conditions.

Assigned Protection Factors (APF) define how much a respirator reduces your exposure. OSHA 29 CFR 1910.134 assigns APF values to each respirator class. SCBA in pressure-demand mode carries a high APF; half-face APRs carry a much lower APF. When the fumigant label requires a certain protection level, you must use a respirator whose APF meets or exceeds what is needed.

SCBA Components You Must Know

Donning, Seal-Checking, and the Buddy Check

Donning sequence (manufacturer order governs; this is the general pattern):

1. Inspect cylinder pressure—verify adequate air supply before donning.

2. Open the cylinder valve fully.

3. Don the harness and position the cylinder.

4. Connect the regulator to the facepiece.

5. Don the facepiece; position and tighten head harness straps from the bottom up.

6. Perform a seal check.

Positive-pressure seal check: Cover the exhalation valve; exhale gently. The facepiece should bulge slightly and hold pressure. Any air leaking out at the face seal indicates a poor fit.

Negative-pressure seal check: Cover the inhalation port; inhale gently. The facepiece should collapse slightly toward your face and hold. Any air rushing in indicates a leak.

Always follow the SCBA manufacturer's specific seal-check procedure—it overrides any general description.

Buddy check: Before entry, your partner visually and physically inspects your unit: cylinder open, connections tight, PASS device armed, regulator functioning. You then check your partner. No one enters alone or without a buddy check completed.

Doffing and Emergency Doff

Doff in a clean area after exiting the hazard zone. Loosen head harness straps from the top down, remove the facepiece, then remove the harness and cylinder. For emergency doff—if a facepiece is trapping you or malfunctioning—know the single-motion release points on your specific unit before you ever enter a structure.

PPE Beyond the Respirator

The fumigant label specifies the complete PPE ensemble. Typical requirements include:

Do not assume one stage's PPE covers another. Read the label for each specific task phase.

OSHA Medical Clearance and Fit Testing

Before you may use a respirator on a job, OSHA 29 CFR 1910.134 requires a medical evaluation to confirm you are physically able to wear respiratory protection, and annual fit testing for tight-fitting facepieces. These are employer obligations but your responsibility to complete. Fit testing and SCBA use cannot be skipped or self-certified.

Key terms10

SCBA (Self-Contained Breathing Apparatus)An atmosphere-supplying respirator that carries its own compressed breathing-air cylinder, providing the highest level of respiratory protection and required for entry into sealed, gassed structures.
Assigned Protection Factor (APF)A OSHA-defined number representing the minimum expected workplace level of respiratory protection a properly functioning respirator class provides to a trained, fitted wearer.
Pressure-Demand ModeAn SCBA operating mode that maintains slight positive air pressure inside the facepiece at all times, preventing toxic gases from leaking inward even if the face seal is imperfect.
Positive-Pressure Seal CheckA facepiece fit test in which the wearer covers the exhalation valve and exhales gently; a proper seal holds pressure without leakage around the face seal.
Buddy CheckA pre-entry procedure in which each fumigation team member inspects their partner's SCBA for cylinder pressure, open valve, secure connections, and armed PASS device before entering a hazardous atmosphere.
PASS Device (Personal Alert Safety System)An alarm device attached to an SCBA that activates automatically if the wearer is motionless for a set period, alerting others to a possible incapacitation emergency.
Air-Purifying Respirator (APR)A respirator that filters contaminants from ambient air using cartridges or canisters; requires a minimum oxygen concentration of 19.5% and is never acceptable inside a sealed, gassed structure.
FIFRAThe Federal Insecticide, Fungicide, and Rodenticide Act; the federal law under which pesticide labels are legally binding—using a pesticide inconsistently with its label is a federal violation.
Permissible Exposure Limit (PEL)The maximum airborne concentration of a hazardous substance to which an unprotected worker may be exposed over a specified time period, as established by OSHA.
Fit TestingA protocol required by OSHA 29 CFR 1910.134 to verify that a specific tight-fitting respirator facepiece forms an adequate seal on an individual worker's face; must be performed before first use and repeated annually.
In class: Instructor demonstrates SCBA components, cylinder pressure checks, positive- and negative-pressure seal checks, buddy-check procedures, and emergency doff; students observe then repeat each step individually on training SCBA units, with the instructor providing corrective feedback before any student is cleared to move to the timed exercise. · Timed SCBA donning drill: students are given a scenario card ('You are entering a tarpauled structure immediately after gas introduction') and must retrieve their SCBA, don it correctly, and perform a seal check within the time frame specified in the equipment manufacturer's guidelines; the instructor records each student's performance on a skills checklist noting any critical errors such as incomplete seal check or wrong regulator setting. · PPE selection decision exercise: students receive six scenario cards describing different stages of a fumigation job (pre-introduction outside the structure, gas introduction, post-introduction monitoring, aeration, clearance testing, post-clearance re-entry) and must select the correct PPE level from a set of labeled equipment cards (SCBA, supplied-air respirator, half-face APF respirator, safety glasses only, chemical-resistant gloves, Tyvek suit); groups compare answers and resolve disagreements using label language and OSHA 29 CFR 1910.134 guidance.
Materials: Training SCBA units (one per two students minimum), SCBA instructor demonstration unit, OSHA 29 CFR 1910.134 reference sheet, fumigant label PPE section, PPE scenario cards, skills checklist, chemical-resistant gloves, Tyvek coveralls, safety glasses
Check: Skills checklist: student must perform a correct SCBA donning and seal check with zero critical errors (critical errors defined on checklist as: cylinder not open, regulator not attached, seal check not performed, buddy check skipped); one repeat attempt allowed with instructor coaching; failure after two attempts requires full lesson repetition before assessment.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

Pesticide Safety and Application
1. A fumigation technician is about to enter a tarpauled structure immediately after phosphine gas has been introduced. Which respiratory protection is required?
Occupational Health and Safety
2. During a pre-entry buddy check, your partner finds that your SCBA cylinder valve is closed. What is the correct action?
Regulatory Compliance
3. Under OSHA 29 CFR 1910.134, which of the following must occur before a worker uses a tight-fitting respirator facepiece for the first time?
Pesticide Safety and Application
4. A fumigant product label requires chemical-resistant gloves during gas introduction but lists only safety glasses for post-clearance re-entry. A technician decides to wear the same SCBA for re-entry 'to be safe.' Which statement is most accurate?
Occupational Health and Safety
5. Which condition makes an air-purifying respirator (APR) unsafe to use regardless of cartridge type?
Occupational Health and Safety
6. During a positive-pressure seal check on an SCBA facepiece, the technician covers the exhalation valve and exhales gently. Air escapes along the left cheek. What does this indicate?
Occupational Health and Safety
7. A fumigation crew of two is preparing to enter a structure. One technician says the buddy check is unnecessary because both workers are experienced and the entry will be brief. Which response is correct?
Pesticide Safety and Application
8. What is the primary purpose of the PASS (Personal Alert Safety System) device on an SCBA?
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