Personal Protective Apparel

WHAT TO WEAR

By Michael Robbins

From "moon suits" to coveralls and everything in between, here’s what you need to know about personal protective apparel

It’s an age-old problem. You’re going out to an impromptu little gathering of the emergency response team and you just don’t know what to wear. Do these Neoprene gloves go with the theme of the event (your hasty telephone invitation mentioned a particular chemical)? Is the Tyvek body suitable for the occasion? Will everyone else be wearing a hood, taped shut at the seams? You certainly don’t want to be the only one to show up at the accident scene wearing a respirator if everyone else has self-contained breathing apparatus. Or maybe you’d like to make a splash when you make your entrance; in that case, perhaps all you need is splash-resistant coveralls.

But the good news about personal protective apparel is that choosing just the right thing to wear is no more difficult -- although it is somewhat more complicated -- than choosing any other sort of protective equipment. First you assess the hazard. Then you check the specifications of all the many, many types of protective apparel to pick out the ones that provide the protection you need. Okay, then it does get a little more involved, because you also have to assess non-hazard issues such as wearer comfort, durability, relative cost and whether to choose disposables or go with re-usables.

The term "personal protective apparel", or PPA, is a little broad, but it’s generally taken to mean protective clothing that covers everything between the extremities normally protected by boots, gloves and a hard hat -- anything from simple cloth coveralls to the full-coverage "space suits" with their own, internal air supply. The term "chemical protective clothing" or CPC is also used, but it applies somewhat more narrowly -- to apparel specifically designed to deal with chemical hazards.

Four levels of protection

For chemical protective clothing (there is also heat- and fire-protective apparel, for example) there are currently four classes or levels of protection that help to simplify the choice. There are two basic rules to making an appropriate selection.

* First, you want to choose a level of protection that will provide full protection from all chemicals that may be encountered.

* Second, you also need to choose the simplest level that will do the job. That’s because, as the level of required protection increases, so do several other factors: the cost of the protective apparel and its cleaning, storage and maintenance; the training (and perhaps in-house certification) of employees wearing it; and the difficulty moving, seeing, communicating and working in the apparel.

Level A: Level A is the highest level of protection, the full monty, if you will. It is used where there is, or may be, the highest degree of hazard and the wearer must be totally protected from any possible contact with the material. This includes any exposure of the skin to the atmosphere (for hazardous gases and vapours that may affect or penetrate the skin).

Level A protection is built around a totally encapsulating body suit made of material that provides protection against the substances that may be encountered. This is perhaps the key consideration: No material is totally impervious to all substances -- you have to choose protective apparel made of material that is designed to deal with the particular hazard. (Manufacturers and safety organizations publish charts that let you choose the best material for your application.)

This level includes boots that protect against the contaminant and also meet the requirements for protective footwear -- hard toe caps and shank; inner and outer gloves that allow for safe handling of the material, both in terms of chemical protection and puncture resistance; a full body suit that protects against any skin contact by the material and any gas or vapour; respiratory protection in the form of supplied air or self-contained breathing apparatus; and a secure means of connecting all the parts so that nothing can enter through the gaps. An outer coverall may or may not be included.

Level B: Level B protection is similar to Level A, with the exception that exposure of skin to the atmosphere is less critical. It is often used where there are hazardous materials and an oxygen-deficient atmosphere. Supplied air or self-contained breathing apparatus is still required. The total encapsulation to separate the wearer from the atmosphere is not required, but everything else applies: full body suit with hood for total splash protection, boots and gloves.

Level C: Level C protection is used when the hazardous material does not present a risk of exposure to the skin. This is used for hazardous materials that can be dealt with through the use of an air-purifying full-face or half-mask respirator (as opposed to supplied air) and chemical resistant clothing, boots and gloves. A face shield and "escape" respirator (that provides five or 10 minutes of supplied air to give the worker time to escape should the situation change) are optional.

Level D: Finally, there is Level D, the lowest level of protection. It is used where the potential exposure is essentially to nuisance materials, rather than hazardous ones. It consists of coveralls, gloves and boots. A hard hat, face shield, dust mask and escape mask are optional, depending on the other hazards that may be present.

In order to choose the appropriate level of protection, it is necessary to ask a number of questions:

* What substance will the wearer be exposed to?

* Does this substance occur as a solid, liquid, gas, vapour or some combination of states?

* Is the substance hazardous to the skin?

* Can the substance -- even if it is a gas or vapour -- be absorbed through the skin?

* Can the substance be hazardous through inhalation?

* What is the maximum possible exposure to the material that may be encountered?

* Is the environment in which people will be working oxygen deficient?

* Is there danger of fire or explosion?

* Are there physical hazards?

Once these questions have been answered, and the material safety data sheet consulted, it starts to become clear which level of protection matches the hazards and the types of potential exposure identified. However, there are different types of suits available within each level of protection -- based primarily on the material the suits are made of. To put it simply, different materials are designed to provide protection to different chemicals. Or, to put it another way, not all Level A suits are suitable -- so to speak -- for all chemicals. You have to choose suit material designed to protect against the chemical you’re dealing with.

How do you do that? The easiest way is with a catalogue from a distributor or manufacturer of PPA. (The distributors may be a better bet, since they list products from all of the major manufacturers; the alternative is to request information from each individual maker of PPA to assemble a relatively comprehensive survey of all the suits and materials available.)

Materials for protective suits tend to be identified by the manufacturer’s trade name, rather than by a generic name for the material: names such as Tyvek or Tychem from DuPont, Responder or CPF1 from Kappler or Hazard-Gard from Kimberly-Clark. Many of these materials are composites, made of layers of different materials; others are fabrics with various types of proprietary coatings. (In some cases, makers of the materials also make the protective clothing; in other cases, the maker of the material makes it available to various manufacturers who, in turn, manufacture protective clothing.)

Each manufacturer publishes a chart listing test performance figures for various chemicals for its material and/or for the suits made of the material. The critical performance factor is "breakthrough time" in minutes -- the amount of time it takes a given chemical, when applied to the outer surface of the test material, to be detected on the inside. (Chemicals travel through protective material by penetration, permeation and degradation. See "Getting Through" page xx.)

To select PPA that is appropriate for the hazard the wearer will face, check the chart. It will tell you how many minutes it takes that chemical to make it through that material; what you’re looking for, in general, is a listing of 480 minutes and a notation of "none detected", meaning that the chemical was not found on the inside of the material after eight hours.

Other factors

Re-usable versus disposable: Both re-usable PPA and its disposable equivalent must meet the same standards in order to be acceptable. The re-usable-versus-disposable debate should not involve questions of quality and durability. Should not. In some particular applications, especially where the PPA is worn for extended periods of time and where there is a high degree of hazard, some users may express a preference for specific, re-usable PPA. In general, however, quality and suitability should not be major issues tilting the balance one way or the other. (Or, to put it more simply, the disposables have to be every bit as good as the re-usables, or you shouldn’t even bother with them.)

The choice should be made on the basis of a number of factors:

* The level of protection required. Level D PPA, which is often worn all day, every day, can be more economical if it is re-usable -- washable, in fact.

* Is PPA used often enough to justify the training and materials needed to decontaminate, clean, inspect and store re-usables?

* When the PPA is used, is it normally expected to become contaminated, or is it primarily used as a precaution? If the PPA is not normally contaminated during use (if the worker wears it to inspect a possible contamination, for example, and normally finds none) the need for decontamination and cleaning are reduced; this suggests re-usables would best suit the need. If the PPA is expected to become contaminated each time it is used, however, disposables may make sense.

* Do the wearers of the PPA have to go quickly from one environment to another? If they need to change PPA each time, disposables may be more convenient.

* Do workers spend a great deal of time working in PPA? If so, the slightly larger selection of types and sizes of re-usables may be a factor.

Storage: The need for storage is one of the more persuasive arguments for using disposables that don’t need to be stored (but which may need to be disposed of as hazardous waste, if they are contaminated). For re-usable PPA, however, storage is one of the key areas of concern. If it isn’t stored properly, it can easily lose its effectiveness.

* Do not store PPA until it has been decontaminated according to the manufacturer’s instructions.

* Inspect PPA before it is stored. This may include testing the material for its ability to maintain positive-pressure.

* Store PPA in a dedicated storage area where it can be hung away from anything that may damage or contaminate it. Folding, stuffing or rolling up the garments may create problems for coated materials that crack or degrade along creases and folds if the suit is not stored properly.

* Make sure PPA is dry before it’s put away, and that it is stored in the proverbial cool, dry place free from any chemical contamination.

* Especially for PPA with higher levels of protection (the Level A and B suits, for example) it may be sound management to assign a qualified person to be in charge of all PPA and to track its every use, the materials it was exposed to, and all cleaning and inspections in a log book that can be consulted during inspections, and when decisions regarding replacement need to be made.

Standards

The fact is that the selection of appropriate personal protective apparel (PPA) can be an extremely complex process. Currently, the standards are somewhat piecemeal. Legislation across Canada calls for "adequate" protection and tends to leave it at that. The National Fire Protection Association (NFPA) has detailed standards for emergency response to hazardous materials spills, particularly addressing vapour and liquid exposure. The European community has a detailed set of standards. But North America is still essentially without a comprehensive set of standards.

That is about to change. The Industrial Safety Equipment Association, an industry group of North American manufacturers, is currently working to develop detailed standards and guidelines for chemical protective clothing. Their draft document seeks to bring a higher level of order to the selection process of chemical protective clothing.

The draft standard, if approved, would establish the following eight "types" of protective garments:

* Type 1a, 1b and 1c -- "gas tight" protective suits;

* Type 2 -- "non-gas-tight" suits;

* Type 3 -- liquid tight clothing;

* Type 4 -- spray-tight clothing;

* Type 5 particulate-tight clothing; and

* Type 6 -- partial body chemical protective clothing.

In addition, the draft standard would introduce performance testing for both the material and the whole suit in areas of leak tightness and chemical resistance. Each of these performance tests would rate the material or suit according to a standard set of performance classifications.

ISEA plans to submit the completed draft to the National Institute for Occupational Health and Safety (NIOSH) for approval, and to the Occupational Safety and Health Administration (OSHA) for inclusion in American legislation. This submission is expected early in the year 2000, with approval possible (but not guaranteed) within the year.

If the more detailed ISEA standards get regulatory approval in the United States, it is expected that Canadian jurisdictions will accept them. While it is far from automatic that Canadian legislation would specifically cite the standard -- it would become a NIOSH standard if accepted -- the practice in Canada is to recognize American and European standards as meeting the burden of "due diligence" -- especially if there is no comparable Canadian standard.

PPA is the last line of defence against chemical hazards -- not the first. Wherever there is a potential for exposure to hazardous materials, every other tool in the accident prevention arsenal should be used to prevent exposure before personal protective equipment comes into play: elimination of the hazard; substitution of less hazardous materials; reduction of the amount of hazardous material on site; engineering controls to contain the material; barriers to prevent its spread if a breach occurs; warning systems to detect a problem early; and training of staff in how to deal with a release of hazardous material.

But, when all of this is done, hazardous materials still exist and, occasionally, someone has to go and clean them up. That’s when knowing just what to wear and showing up dressed for the occasion make all the difference in the world.

Michael Robbins is a writer specializing in health and safety.

Box

ROUTES OF ENTRY

Hazardous substances can enter the body in four different ways, by four different routes. The choice of PPA is largely based on the type of substance and the possible routes it could take into the body.

* Skin absorption: Many substances are hazardous to the skin itself, or can enter body tissue and access the circulatory system by working their way through the skin. Liquids are usually seen as the biggest problem, but this can be deceptive. Some solids can damage the skin or leave a residue that reacts with moisture or skin oils to take on a form that can penetrate. And often overlooked is the fact that gases and vapours in the air can also enter through exposed skin.

* Inhalation: Gases, vapours, dust and fumes can all be inhaled, and may require breathing protection. Particulates, the dust and fumes, can be controlled with one of nine classes of particulate respirators (see "A Fitting Selection", OHS Canada, March, 1998, page 66); gases and vapours will require cartridge respirators that use a chemical cartridge to neutralize these substances. Not all types of gases and vapours -- depending partly on their concentration in the air -- can be controlled with cartridge respirators, however. In some circumstances, you will require supplied air respirators or self-contained breathing apparatus (SCBA).

* Ingestion: There are several ways to ingest, or swallow, a hazardous material. You can get it on your hands and then hold a sandwich or a cigarette; you can have it settle out of the air (or even be spilled) onto or into a snack or drink; and -- an often overlooked route for larger particulates -- you can breathe them in and your lungs will capture them in mucus and clear them to the back of the throat, where they are then swallowed.

* Injection: Finally, hazardous material can enter the body by being physically inserted through the skin, such as when one is injured by a sharp, contaminated object.

Sidebar

GETTING THROUGH

Despite what the material safety data sheets for various hazardous materials may suggest, there is no such thing as an "impervious material". Unlike protective gloves, in which the materials are normally identified by type -- vinyl, neoprene, polyvinyl alcohol, natural rubber and so on -- protective clothing materials are usually identified by the trade name of the manufacturer. This is because protective clothing materials are often combinations or layers of different materials designed to provide both chemical resistance and the strength to withstand tearing and puncturing. However, the principle behind selecting the appropriate material is the same as for gloves: Consult the chart published by the manufacturer or distributor to see what material is suitable for protecting against the hazardous material or materials you expect to encounter.

There are several ways that hazardous materials can make it through gloves, body suits or other protective material: permeation, penetration and degradation. The charts used for matching the material to the hazard will list test results based on these three processes.

Permeation: The best example of permeation is one that we have all witnessed (and perhaps wondered about) on the day after a birthday party. Notice how the helium balloons that were floating around the ceiling are all on the ground a day later? That’s because the helium gas permeates the natural rubber skin or plastic skin of the balloon. There is no hole for the gas the leak through; it actually passes, one molecule at a time, through the skin, driven by the gas pressure inside, and leaves the balloon intact.

Penetration: Another way for gas or vapour to pass through a protective material is for it to seep through holes in the seams, joints, zippers, imperfections and even undetected damage. This applies to hazardous gases and vapours, but may be of particular concern with liquids that may splash onto the protective clothing. If the breach in the material is big enough, it may actually seep through; but it can also be "wicked" through the material by any absorbent material that may be present, or evaporate and force the vapour through the gap. Also, the normal flexing of the material as the wearer moves around can create a bellows effect that actually sucks the outside atmosphere in through any available gap.

Degradation: Another way for hazardous materials to make it through protective clothing is through attacking the material itself. Some hazardous materials react chemically with some materials; the result is that the structure of the material is changed, or "degraded". The chemical may actually dissolve the protective material, or make it brittle so that it crumbles, or change its chemical structure into something that lets the hazardous material through.

Top

Back to contents