3.3 PPE Selection, Inspection, Donning, and Doffing Procedures

3.3 PPE Selection, Inspection, Donning, and Doffing Procedures

The operational success of a hazardous materials entry depends not only on selecting the proper protective ensemble, but also on rigorous inspection, physiological monitoring of personnel, strict adherence to the buddy system, and meticulous execution of donning and doffing procedures. Under NFPA 470, improper donning can lead to suit failure during hot zone entry, while improper doffing is a leading cause of secondary chemical contamination among emergency response personnel.

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The Chemical Protective Equipment Selection Process

Selecting chemical protective clothing (CPC) requires matching the specific chemical hazard against validated manufacturer test data and environmental operational constraints:

1. Utilizing Chemical Compatibility and Resistance Charts

Responders must consult manufacturer Chemical Resistance Charts or reference databases (such as the NIOSH Pocket Guide, CHRIS manual, or chemical SDS) for the target substance. Selection evaluates three critical parameters:

• Breakthrough Time: The time elapsed between initial chemical contact on the outer suit surface and detection inside the suit. Selected suits should have a breakthrough time exceeding the planned working duration (typically seeking >480 minutes, or at minimum double the planned hot zone stay).
• Degradation Rating: Published ratings (e.g., Excellent, Good, Fair, Poor, or Not Recommended) indicating how well the fabric retains physical integrity upon chemical exposure.
• Permeation Rate: The speed at which chemical molecules diffuse through the fabric after breakthrough occurs.

2. Environmental and Operational Factors

• Physical Hazards: Operations involving sharp metal, broken glass, or tight spaces require high puncture, tear, and abrasion resistance, or outer sacrificial coveralls over chemical suits.
• Ambient Temperature Extremes: Low ambient temperatures cause chemical suit elastomers to become stiff and brittle, increasing tear risks. High temperatures dramatically increase heat stress risks for wearers.

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Physiological Factors, Medical Monitoring, and Heat Stress Management

Wearing chemical protective ensembles—especially fully encapsulating Level A suits—creates an artificial, micro-climate environment that severely restricts the body's natural thermoregulation (sweat evaporation).

1. Heat Disorders and Recognition

Because chemical suits trap 100% of body heat and humidity, responders are at extreme risk for thermal stress:

2. Mandatory Pre-Entry and Post-Exit Medical Monitoring

NFPA 470 mandates baseline medical evaluations for all personnel entering the hot zone in Level A or Level B ensembles:

• Pre-Entry Monitoring Criteria: Vitals measured within 30 minutes prior to entry:
  • Heart Rate: Must be below 70–80% of maximum predicted heart rate (typically < 100–110 bpm).
  • Blood Pressure: Diastolic must typically be < 90–100 mmHg; Systolic < 140–160 mmHg (per local medical protocol).
  • Body Temperature: Normal baseline (< 99.5°F / 37.5°C).
  • Hydration Status: Pre-entry hydration (16–32 oz of water/electrolytes).
  • Medical Disqualification: Personnel exhibiting elevated blood pressure, fever, irregular heart rhythm, dehydration, or skin rash are barred from entry.
• Post-Exit Monitoring: Personnel undergo immediate vitals evaluation following decontamination and doffing. Body weight loss is measured to estimate fluid loss, and personnel must rehydrate before being considered for subsequent entries.

3. In-Suit Active Cooling Systems

To extend working duration and reduce thermal strain, responders utilize active cooling garments worn underneath chemical suits:

• Ice Vests / Phase-Change Vests: Contain frozen water or phase-change petroleum paraffin packs that absorb body heat.
• Liquid-Circulating Garments: Pump chilled water through tubing woven into an inner vest.
• Vortex Tubes: Use compressed air from an external line to generate cold air circulated inside the suit.

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The Buddy System and Rapid Intervention Team (RIT) Protocols

Safety regulations under OSHA 29 CFR 1910.120 and NFPA 470 strictly enforce the Buddy System for all hot zone and warm zone operations:

1. Two-In / Two-Out Requirement: Entry into the hot zone requires a minimum of two entry personnel who must maintain continuous visual, voice, or physical contact at all times.
2. Dedicated Backup Team (Rapid Intervention Team): A secondary team of at least two responders must be fully equipped in the exact same level of PPE as the entry team. The backup team stands staged in the Warm Zone, ready to deploy immediately if an entry team member experiences SCBA failure, suit tearing, heat collapse, or entrapment.

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Inspection and Pressure Testing Protocols

Chemical protective clothing must undergo rigorous inspection prior to deployment:

1. Pre-Use and Periodic Inspection

• Inspect suit fabric for pinholes, cracks, tears, discoloration, or sticky degradation.
• Check storm flaps, zippers (lubricate zipper teeth with paraffin wax), facepiece visors, and seam seals.
• Inspect suit overpressure relief valves (exhalation valves) to ensure free movement and proper seating.

2. NFPA 1991 Pressure-Testing (Inflation Testing)

Level A gas-tight ensembles must undergo periodic pressure testing (at least annually and after every use or repair) per manufacturer and ASTM F1052 standards:

• The suit is inflated with compressed air to a specified test pressure (typically ~5 inches of water gauge).
• Pressure is monitored over a 3- to 5-minute stabilization and test period.
• If pressure drops beyond allowable limits (e.g., > 20% loss), the suit fails gas-tight integrity and must be removed from service.

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Step-by-Step Donning and Doffing Sequence

Executing donning and doffing in a structured, standardized sequence prevents accidental suit damage and eliminates secondary chemical contamination.

Step-by-Step Donning Protocol (Assisted by Dressing Assistant)

1. Pre-Donning Medical Check: Complete vitals evaluation and hydration.
2. Equipment Check: Verify SCBA cylinder pressure (min 90–100% full), test radio communication, and perform Level A suit pressure test verification.
3. Step Into Suit: Wearing inner cotton/undergarments, step through the suit legs into suit booties and boots. Pull suit legs down over outer boot tops.
4. Don Inner Gloves: Put on inner chemical-resistant gloves (e.g., Silver Shield).
5. Don SCBA Harness and Facepiece: Don SCBA shoulder straps; place facepiece over head, tighten straps evenly, and perform positive and negative face-seal checks. (Do not connect regulator to facepiece yet to conserve air).
6. Enclose Wearer: Dressing assistant pulls suit hood over the SCBA harness and wearer's head. Wearer places arms into suit sleeves and outer gloves.
7. Seal Suit Closure: Assistant carefully zips the gas-tight zipper while pulling fabric taut to prevent teeth jamming. Close storm flap and seal adhesive tape.
8. Final Entry Check: Immediately prior to hot zone entry, wearer connects SCBA regulator, assistant checks pressure gauge, confirms radio contact, and verifies complete suit closure.

Step-by-Step Doffing Protocol (Conducted in Decontamination Line)

1. Gross Decontamination: Entry team undergoes thorough wash and rinse steps in the decon corridor to remove bulk surface chemicals from the suit.
2. Enter Doffing Station: Step into the clean end of the decon line. Dressing assistant MUST wear appropriate decon PPE (typically Level B/C splash gear with gloves and APR).
3. Open Suit Closure: Assistant unseals storm flap and carefully unzips suit zipper from top to bottom.
4. Outward-Rolling Suit Removal: Assistant folds the top of the suit outward and downward, rolling contaminated outer suit surfaces inward away from the wearer.
5. Withdraw Arms and Body: Wearer withdraws arms from sleeves (inner gloves remain on wearer's hands). Assistant pulls suit down over boots. Wearer steps cleanly out of suit boots directly into the clean zone without touching contaminated suit exteriors.
6. Remove Respiratory Gear: Disconnect regulator; remove SCBA facepiece and harness; place onto clean equipment tarp.
7. Remove Inner Gloves: Peel inner gloves off inside-out to prevent hand contamination.
8. Post-Doffing Medical Re-evaluation: Proceed immediately to post-exit medical monitoring, shower, and rehydration.