Editor’s note: For more information on this topic, refer to the AIHA publication Chemical Protective Clothing, from which some of this article is derived.

Personal protective equipment is generally considered a last resort in the hierarchy of controls. By its very nature, PPE implies that the wearer is in proximity to an exposure source, which places him or her at a higher risk for injury in the event of a failure. Still, PPE is an important tool for worker protection and a critical defense-in-depth element. However, when possible, we should use multiple controls to protect workers. This article focuses on work environments that can contaminate PPE surfaces with highly toxic or infectious materials. It also addresses considerations that can help prevent secondary or tertiary exposures, along with ways to mitigate these risks.  The OSHA publication “Personal Protective Equipment” describes PPE as “equipment worn to minimize exposure to a variety of hazards”; examples include “gloves, foot and eye protection, protective hearing devices (earplugs, muffs), hard hats, respirators, and full body suits.” The document provides a general overview of PPE types and describes OSHA’s expectations for employers regarding exposure assessment and the care, donning, and doffing of PPE.  Procedures for decontaminating PPE are discussed in “Occupational Safety and Health Guidance Manual for Hazardous Waste Site Activities,” a 1985 publication of the Department of Health and Human Services. This manual provides the following statement: 
Decontamination methods vary in their effectiveness for removing different substances. The effectiveness of any decontamination method should be assessed at the beginning of a program and periodically throughout the lifetime of the program. If contaminated materials are not being removed or are penetrating protective clothing, the decontamination program must be revised.
That said, simply removing a contaminated component of PPE (without causing secondary exposure) can be just as effective as removing the contaminant from the PPE. THE KEY ELEMENTS OF DECONTAMINATION The decontamination and doffing processes consist of three elements: individuals who wear the ensemble or who assist someone in removing it; procedures or practices; and equipment. A failure in any element can cause unintentional exposures to workers, contractors (for example, through waste or laundry streams), or family members (for example, through infectious diseases).  In terms of the classic industrial hygiene source, pathway, and receiver approach, surface contaminants on PPE ensembles can be killed or neutralized, cleaned or flushed away, or “fixed” to the PPE (for example, by applying water mist) and discarded. Fixing contaminants and discarding the contaminated PPE is also an effective tactic in maintaining continuity of worker protection.
The key is that we should always assume the protective ensemble surfaces are contaminated. The following sections provide details on how industrial hygienists can ensure that PPE provides continuity of protection to workers when the components of the ensemble themselves are a potential exposure source, and discuss the concepts and actions an IH can use to eliminate potential exposure pathways while the contaminated ensemble is removed piece by piece. MIX AND MATCH: ENSEMBLES AND COMPONENTS   Consider the protective ensemble as a collection of components working together to provide continuous worker protection. We will assume that each item functions as intended—that there will be no failures due to chemical permeation (molecular movement through the material), penetration (gross movement through the material or openings), or degradation (chemical action on the material)—so that we can examine other potential exposure and cross-contamination mechanisms. We will also assume proper selection of PPE capabilities suitable for the hazards: toxicity (acute, chronic, or infectious); physical characteristics (solid, liquid, gas, free flowing, viscous); physical hazards (flammability, combustibility); environmental persistence (how long the materials can be expected to remain toxic or infectious); and chemical properties (vapor pressure, solubility, and reactivity). Planning and selection are the predominant factors in determining how the doffing will be performed. Many types of equipment—with many possible combinations—are available from various manufacturers. How do we ensure the ensemble provides continuous protection throughout the doffing process? Nearly every component of PPE has at least one opening—zippers, buttons, Velcro, snaps, cuffs, ties, laces, buckles, valves, or sealing surfaces (for example, respirators). Each opening is a prospective failure point. Design features such as harnesses, regulators, canisters, cartridges, hoses, belts, zipper covers, exhaust valves, gauntlets, and belts, or even PPE armpits and crotches, can result in “nooks and crannies” that can harbor contamination. The PPE item itself, then, can cause secondary exposures. Furthermore, tape used to secure openings at the head, neck, wrists, and ankles can also cause secondary exposures. These interfaces need to be evaluated for their ease of removal and for their ability to withstand forces acting on them (in other words, pulling, tugging, cutting, and so on). THE DECONTAMINATION PROCESS AND ITS KEY LEADERS All work with highly toxic or infectious materials should be treated as hazardous. Assessment of hazards should consider worker protection in the context of tasks, sources, routes, and environment. Industrial hygienists can help improve the effectiveness of decontamination and doffing by developing or documenting plans and procedures, selecting individual components that comprise the protective ensemble, observing or monitoring decontamination and doffing actions, or helping the users modify work behaviors based on observations or data. Decontamination and doffing actions are learned skills that can be improved by combining technical knowledge and task-based cross-training with drills, dry runs, briefings, feedback, and open communication.
Variables to consider include general work practices,  equipment selection, donning technique, training, and experience. For example, hands and feet almost always become contaminated when the work processes are contaminated or infectious, or involve leaking. Good work practices minimize the extent of direct contact with contaminant sources by staying out of product and avoiding kneeling positions or overhead work. Extended work hours should be avoided, as fatigue can diminish situational awareness or level of learned skills. It is also critical to address safety hazards that can degrade protective barriers and to plan for injured, immobile, sick, or unconscious workers. Decontamination and doffing efforts are most successful when work activities and site variables remain consistent, as in a laboratory or a facility that has well-characterized chemical, biological, or radiological hazards. 
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Decontamination and doffing efforts are most successful when work activities and site variables remain consistent.
Feedback and open communication are imperative when circumstances—such as an emergency response—require the blending of people, processes, and equipment from multiple agencies, organizations, or companies. Key leaders such as the IH, workers, and supervisors can be most effective when all parties are actively engaged and openly communicating with one another. Include PPE wearers in the conversation—they can often help identify relatively minor details that can lead to big improvements.  A SYSTEMS VIEW Decontamination and doffing actions must be compatible with one another when the primary goal is to extricate the wearers without exposing them to surface contaminants. The nature of the contaminant, component interfaces, component surfaces, and decontaminating agents—as well as the practices, procedures, and equipment—can affect the wearer’s ability to successfully doff the ensemble without causing secondary exposures. Absent outright component failures—such as permeation, penetration, degradation, or breakthrough (transfer to the inner surface)—a number of possibilities exist for eliminating or minimizing injury or secondary exposures. Although proper PPE selection is important, the following areas are critical when the protective ensemble surfaces are contaminated with highly toxic or infectious materials. 1. Protection from Further Harm The work environment itself is stressful. PPE can exacerbate this for the wearer by increasing heat stress and the potential for heat strain, impeding the ability to maintain hydration, impairing verbal communication, reducing tactile sensations and diminishing dexterity, and reducing visual clarity or field of view. These mental and physical factors can lead to fatigue, which can impair judgment. The decontamination and doffing processes should anticipate this degraded performance. The processes should include frequent checks for alertness or physiological responses (for example, sweat rates, pupil dilation) and accommodations for physical fatigue (for example, by providing stools, chairs, or walkers). Time management is also important, and must be included with other wellness considerations. Don’t forget to consider accidents, medical emergencies, and “last one out” accountability checks. It is important to be prepared and know how you will handle an injury, in-suit emergency, or the last person out of the “decon” line, who may be short on assistance. 2. Component Selection and Donning Many individual components are available for selection when establishing the protective ensemble. When possible, choose components that are known to be compatible with one another, especially at interface points such as the head, neck, and wrists. Tape can hold things together reasonably well, but it won’t positively seal out contaminants; rather, it can harbor contaminants and potentially interfere with doffing actions. A better option is to choose components designed to work together. For example, respirator-fit hooded coveralls, when properly sized and fitted to the wearer, can eliminate the need to tape a respirator-hood interface. When a separate hood must be secured to a protective garment, confirm the respirator interface/seal, provide the wearer enough freedom of movement to keep taped and mated surfaces from coming loose, and account for interference by other components, such as harnesses for self-contained breathing apparatuses.  When donning, consider layering or “shingling” wrist, ankle, and footwear openings. For example, a gauntlet covering the boot or foot is preferable to using tape to prevent decon water from pooling inside a shoe or boot. Alternatively, a disposable garment might be field fitted by splitting the integrated bootie so that the lower leg can be drawn over the outside of a boot and secured with tape.  It’s also important to keep in mind protective garment seams: fully taped seams can be stronger and less vulnerable than serged seams, though each type can be used effectively when properly matched to the hazards and the operating environment. 3. Decontamination Methods All decontamination methods can be grouped into one of two types: wet or dry. Each has advantages and disadvantages. Dry methods, such as HEPA vacuuming, can be time consuming and may exacerbate worker strain when heat stress is an issue. Simply doffing the protective components may be sufficient if the surface contaminant is a viscous or persistent material. In other instances, it may be possible to fix contaminants to surfaces by misting. However, wet methods, especially showers or flooding, can wash contaminants through ensemble openings. The most vulnerable points in a protective garment include the head, neck, chest, and wrists. Workers should not be able to feel water inside a protective suit during decontamination. Note that Level “A” and some encapsulating Level “B” suits, when properly used, rarely have these vulnerabilities and thus can be more appropriate when exposure control is critical. 4. Work Practices To the extent possible, protected workers should minimize direct contact with the materials. They should be instructed to walk around, rather than through, product or contaminated surfaces. Knees and elbows act as “force concentration points” when kneeling or leaning on surfaces, and these actions can cause mechanical damage to the protective garment or drive contaminants through it. Overhead work can also result in significant contact with contaminants. Try to prevent contact with exposure sources by keeping work activities at normal height (that is, between the shoulders and knees). 5. Doffing Practices
A PPE wearer is most susceptible to cross-contamination and exposure while doffing PPE during the decontamination process. Stiff brushes can splatter surface contaminants and decon water over considerable distances and serve as a resuspension mechanism. When used with too much force, showers and sprayers can also resuspend contaminants and cause considerable spreading. It is important to remove contaminated items to the side of the wearer to avoid dropping contaminants on his or her head or shoulders. Teach assistants to reach around, rather than over, the people whose PPE they are removing. It can be useful to consider the relative heights of workers and assistants before pairing them. 6. Tools and Equipment
Every element of a respirator is likely to be contaminated: facepiece, straps, canisters/cartridges, regulators, high-pressure hoses, web belts, and so on. The most notable exception is that encapsulating “A” or “B” protective garments usually provide a high level of protection from gross contamination; otherwise, respirators and ancillary equipment can harbor contaminants that can cause secondary exposures during doffing. Keep contaminated hoses, belts, and straps from touching the worker while his or her PPE is removed. Workers should practice doffing respirators without looking down; contaminants can be dislodged from regulator and canister surfaces when they touch or bump the worker’s chest. When possible, select only tools whose surfaces can be easily decontaminated. 7. Reuse of PPE Decontaminating garments and components can be costly. “Single-use” items, which are discarded and replaced instead of decontaminated, may be less costly than decontamination and re-use.  Consider which items can undergo further decontamination after doffing. Footwear, especially heavy overboots, can always be subject to further decon if they are to be re-used; spend as little time as possible on them when extricating the worker.  TALK TO THE USERS Decontamination and doffing are successful only when the worker is safely extricated from a contaminated protective ensemble without secondary exposures. When highly toxic or infectious materials are involved, continuous health monitoring for signs and symptoms of exposure is necessary. Select the right components, understand interfaces, provide drills and training, look for vulnerabilities, and—above all—talk directly to the wearers. You might be surprised by what you can learn.   FRED BOLTON is a certified industrial hygienist at Los Alamos National Laboratory. He has served as a hazmat responder and training instructor, which included providing technical support to several DOE national response teams. He was also responsible for testing and evaluating procedures for doffing contaminated protective ensembles in both military and civilian applications. He can be reached via email.

ROB BROWN is president of Gloves By Web, a provider of personal protective apparel and PPE for many industries, including EMT, pest control, and cannabis. He can be reached at (414) 975-7500 or via email.

ROBERT N. PHALEN, PHD, CIH, is an associate professor of Industrial Hygiene at University of Houston-Clear Lake in Houston, Texas. He can be reached at (281) 283-3753 via email.

CURTIS HINTZ, CIH, CSP, is an industrial hygiene manager with The Dow Chemical Company in Freeport, Texas. He can be reached at (979) 238-9682 or via email. Send feedback to The Synergist.
REFERENCES AIHA: Chemical Protective Clothing, 2nd edition (2003). OSHA: Personal Protective Equipment (PDF, 2004). U.S. Department of Health and Human Services: “Occupational Safety and Health Guidance Manual for Hazardous Waste Site Activities” (PDF, October 1985)
Photo credit: Los Alamos National Laboratory
 Considerations for Decontaminating Personal Protective Equipment
BY FRED BOLTON, ROB BROWN,
ROBERT N. PHALEN, AND CURTIS HINTZ
CONTINUITY of Protection
Although the print version of The Synergist indicated The IAQ Investigator's Guide, 3rd edition, was already published, it isn't quite ready yet. We will be sure to let readers know when the Guide is available for purchase in the AIHA Marketplace.
 
My apologies for the error.
 
- Ed Rutkowski, Synergist editor
Disadvantages of being unacclimatized:
  • Readily show signs of heat stress when exposed to hot environments.
  • Difficulty replacing all of the water lost in sweat.
  • Failure to replace the water lost will slow or prevent acclimatization.
Benefits of acclimatization:
  • Increased sweating efficiency (earlier onset of sweating, greater sweat production, and reduced electrolyte loss in sweat).
  • Stabilization of the circulation.
  • Work is performed with lower core temperature and heart rate.
  • Increased skin blood flow at a given core temperature.
Acclimatization plan:
  • Gradually increase exposure time in hot environmental conditions over a period of 7 to 14 days.
  • For new workers, the schedule should be no more than 20% of the usual duration of work in the hot environment on day 1 and a no more than 20% increase on each additional day.
  • For workers who have had previous experience with the job, the acclimatization regimen should be no more than 50% of the usual duration of work in the hot environment on day 1, 60% on day 2, 80% on day 3, and 100% on day 4.
  • The time required for non–physically fit individuals to develop acclimatization is about 50% greater than for the physically fit.
Level of acclimatization:
  • Relative to the initial level of physical fitness and the total heat stress experienced by the individual.
Maintaining acclimatization:
  • Can be maintained for a few days of non-heat exposure.
  • Absence from work in the heat for a week or more results in a significant loss in the beneficial adaptations leading to an increase likelihood of acute dehydration, illness, or fatigue.
  • Can be regained in 2 to 3 days upon return to a hot job.
  • Appears to be better maintained by those who are physically fit.
  • Seasonal shifts in temperatures may result in difficulties.
  • Working in hot, humid environments provides adaptive benefits that also apply in hot, desert environments, and vice versa.
  • Air conditioning will not affect acclimatization.
Acclimatization in Workers