Archive for September, 2010

Safety Supplies Michigan Tennessee Wisconsin – Amerisource Industrial Supply

PPE OVERVIEW – SAFETY RULES

The selection of appropriate protective gear is based on the hazards anticipated or recognized. Complete protection calls for assembling a set of gear including respirator, hardhat, safety glasses or face shield (preferably both), body covering (coveralls, pants and jacket), gloves and safety boots/shoes (steel toe and shank). Omitting one item may compromise the individual’s safety.  Some pieces of protective equipment, such as hardhats and boots, have specific standards for manufacture and only those items meeting these standards should be used. However, there are no such standards for chemical protective clothing. Selections must be based upon judgment.

Head Protection

The hardhat, a basic piece of safety equipment used in any work operations, must meet ANSI Z89.1 1986 specifications for protection. Manufacturers have adapted hardhats so that ear protection and faceshields may be easily attached. Hardhats are adjustable so a liner can be worn during cold weather. A chin strap is advantageous when work involves bending and ducking. It also helps secure the hardhat to the head when full face masks are worn.

Faceshields that attach to hardhats provide added protection. A combination that leaves no gap between the shield and the brim of the cap is best because it prevents overhead splashes from running down inside the faceshield. The faceshield must meet ANSI Z87.1‑1989 specifications.

Eye Protection

Safety glasses must also meet ANSI Z87.1‑1989. They should be standard safety gear when the respiratory protection is a half‑face mask with no faceshield. Both safety glasses/goggles and a faceshield are advisable as long as they do not impair visibility.  Safety glasses should be of the type that incorporate face shields.

Ear Protection

Ear plugs or muffs should be issued when noise may be a problem, such as around heavy machinery and impact tools. 

Foot Protection

Footwear worn during site activities (including leather work boots and rubber boots) must meet the specifications of ANSI Z41‑1991. The material used to make the boots is not subject to any standards. Protection against liquid hazardous chemicals requires a boot of neoprene, PVC, butyl rubber, to some other chemical resistant material.

Boots are available in two styles: pullover and shoe boot. Pullovers may be inexpensive enough to be considered disposable; otherwise they must be completely decontaminated. With chemical resistant boots, the pant leg should be outside and over the boots to prevent liquids from entering.

Hand Protection – Gloves

The hands are as susceptible to contamination as the feet. Gloves must resist puncturing and tearing as well as provide the necessary chemical resistance. Heavy leather gloves may be worn over chemical protective gloves when doing heavy work. If they become contaminated, they should be discarded because leather is difficult to decontaminate. Jacket cuffs should be worn over glove cuffs to prevent any liquid from spilling into the gloves. If hands are elevated above the head during work, the gloves should be sealed with tape to the coveralls or splash suit.

When selecting gloves consider thickness and cuff length. The thicker and longer the glove the greater the protection. However, the material should not be so thick that it interferes with the necessary dexterity. Two pair of gloves should also be considered for extra protection of the hands if the outer glove is torn or permeated. A pair of inner gloves also adds an extra layer of protection for the hands during the removal of outer gloves and other chemically protective items. 

Body Protection

Clothing to protect the body against hazardous liquids, gases, or vapors is available in a variety of styles and materials.

If the hazard present is known to be minor or simply a nuisance, minimal protection is warranted. This may be in the form of garments of MicroMax which are disposable or Nomex which are durable. Both are available as coveralls suitable for field use. As the hazards to the body increase, so does the level of protection needed. A splash suit made of PVC is suitable for a liquid such as an acid or base or when there will be minimal contact with organic materials. Some are inexpensive enough to be disposable.

If the material is more toxic, then more protection must be utilized. Splash suits similar in design to the PVC splash suits are good barriers against toxic hazards. These are made of neoprene and butyl rubber.

Toxic vapor/gases require the most complete protection, the best being fully encapsulating suits. The suit must not allow any penetration or permeation. Zippers must be properly sealed and seams properly connected and sealed to protect against vapors. Fully encapsulating suits also require the basic safety items such as safety boots and hardhat, along with a source of breathing air.

Wearing protective clothing creates some problems, the main one being that the body is shielded from normal circulation of air. Perspiration does not evaporate, thus eliminating the body’s main mechanism for cooling.  A cool towel on the nape (back of the neck) will effectively cause the hypothalamus (the body’s thermostat to reduce the body’s temperature immediately by   2 - 4 degrees in a heat stress situation.  With that gone, the body is prone to heat stress, including heat stroke, which can be fatal. Heat related problems are very common when temperature rises above 75 degrees F. Work schedules for persons wearing fully encapsulating clothing must be closely and conservatively regulated lest heat stress becomes more of a threat than the chemical hazard itself.

The best way to combat heat stress is to allow the body to cool normally. The most efficient body cooling process is by evaporation. Someone wearing protective clothing that has no ventilation perspires profusely. If the perspiration remains in contact with the skin, it has a better chance of evaporating and cooling the body surface. If the perspiration is allowed to run off the body quickly, less evaporation occurs. This happens when shorts are worn under a fully encapsulating suit.

Suit material can become very hot and cause severe burns if it contacts the wearer’s bare skin. Long cotton underwear is a good solution to this problem. It clings to the body when soaked with perspiration, thus allowing the greatest amount of cooling by evaporation and also protects the body from burns caused by the suit itself.

During extended periods of work in fully encapsulating suits, some sort of “cooling” must be provided to the wearer. The best method is to schedule frequent rest periods. If this is not adequate, a cooling device should be employed. Effective cooling units are available for use with supplied‑air units. A vortex tube separates the air into cool and warm components, releasing the warm air outside the suit. When self-contained air is used for breathing, the cooling device must also be self-contained. For example, vests have been designed to carry ice packs. There are other commercial devices available to combat heat generated by fully encapsulating suits.

Many workers spend some part of their working day in a hot environment. Workers in foundries, laundries, construction projects, and bakeries, to name a few industries, often face hot conditions which pose special hazards to safety and health.

In selecting the protective material, the following should be considered:

	Chemical resistance, which is the most important. When clothing contacts a hazardous material, it must maintain its structural integrity and protective qualities.
	Strength, which is based on resistance to tears, punctures, and abrasions, as well as tensile strength.
	Flexibility, clothing easy to move in and work in. Flexibility is especially important in glove materials.
	Thermal limits affect the ability of clothing to maintain its protective capacity in temperature extremes. Thermal limits also affect mobility in cold weather and transfer of heat to the wearer in hot weather.
	Cleanability, difficult and expensive if protective clothing is not cleanable. Some materials are nearly impossible to clean adequately under any circumstances.  Disposable clothing is sometimes used.
	Lifespan, which is the ability to resist aging, especially in severe conditions over time. This should be balanced against the initial cost of the garment.

Chemical Resistance

Protective material must be able to resist degradation, penetration, and permeation by the contaminant. Any of these actions may result upon contact, depending on factors such as concentration and contact time. 

Degradation

Degradation is the result of a chemical reaction between the contaminant and the protective material. Damage to the material may be slight or as severe as complete deterioration. The reaction may cause the material to shrink or swell, become brittle or very soft, or completely change its chemical and physical structure. Changes such as these may enhance or restrict permeation or allow penetration by the contaminant.

Penetrability

A chemical penetrates a protective garment because of its design and construction imperfections, not because of the inherent material from which it is made. Stitched seams, button holes, porous fabric, and zippers can provide an avenue for the contaminant to penetrate the garment. A well designed and constructed protective suit with self‑sealing zippers and lapped seams made of a nonporous degradation‑resistant material prevents penetration, but as soon as the suit is ripped or punctured it loses its ability to prevent penetration. A material may also be easily penetrated once degraded.

Permeability

The ability of a protective material to resist permeation is an inherent property. A contaminant in contact with the protective material establishes a concentration gradient. The concentration is high on the contact surface and low inside. Because the tendency is to establish equilibrium, diffusion and other molecular forces “drive” the contaminant into the material.

When the contaminant passes through the material to the inside surface, it condenses there. The process of permeation continues as long as the concentration remains greater at the contact surface.  The permeation rate is based on several factors. Rate is inversely proportional to the thickness of the material and directly proportional to the concentration of the contaminant.

The amount or degree of permeation is related to the exposure conditions, especially contact time, which ultimately dictates how much of the contaminant permeates the protective material. Thus a conscious effort should be made to avoid prolonged exposure or contact with any hazardous contaminant, even when wearing protective clothing.  No material resists permeation by all agents.

Decontamination

Once a contaminant contacts a protective material, the garment must be decontaminated. With many materials, it is impossible to completely remove all contamination. Materials such as butyl rubber and Viton, which can be effectively decontaminated and cleaned, are also expensive. In some situations disposable clothing may be advantageous.

Chemical Resistance Charts

Tables are available indicating relative effectiveness of various protective materials against generic classes of chemicals.  Most tables only reflect ability to resist degradation. A protective material may resist degradation by a contaminant, but still be very permeable to it. Such charts are useful when used with discretion and when the seriousness of the hazard is properly evaluated. If a chemical is extremely toxic, then any activity involving it should be re‑evaluated.

Permeability data are available from manufacturers and independent testing laboratories. If there is a question about permeability of a material in contact with a specific contaminant, a sample swatch of the material should be tested by a recognized laboratory for permeability to that chemical.

EPA RECOGNIZED LEVEL OF PROTECTION

U.S. Environmental Protection Agency levels of protection can be used as a starting point for assembly of protective clothing ensembles. However, each ensemble must be tailored to the specific situation to provide the most appropriate level of protection.

	Level A (highest)
	Level B
	Level C
	Level D (lowest)
	Reasons to move to a higher level of protection
	Reasons to move to a lower level of protection

  

EPA Levels of Protection

When response activities are conducted where atmospheric contamination is known or suspected to exist, personal protective equipment must be worn.

Personal protective equipment is designed to prevent/reduce skin and eye contact as well as inhalation or ingestion of the chemical substance.

Protective equipment to protect the body against contact with known or anticipated chemical hazards has been divided into four categories.

LEVEL A

Level A protection should be worn when the highest level of respiratory, skin, eye and mucous membrane protection is needed.

Personal Protective Equipment

	Positive pressure (pressure demand), self contained breathing apparatus (NIOSH approved), or positive-pressure supplied air respirator with escape SCBA.
	Fully encapsulating chemical protective suit.
	Gloves, inner, chemical resistant.
	Gloves, outer, chemical resistant.
	Boots, chemical resistant, steel toe and shank; (depending on suit boot construction, worn over or under suit boot.)
	Underwear, cotton, long-john type.*
	Hard hat (under suit).*
	Coveralls (under suit).*
	Two-way radio communications (intrinsically safe/non-sparking).** Optional

LEVEL B

Level B protection should be selected when the highest level of respiratory protection is needed, but a lesser level of skin and eye protection. Level B protection is the minimum level recommended on initial site entries until the hazards have been further identified and defined by monitoring, sampling, and other reliable methods of analysis, and equipment corresponding with those findings utilized.

Personal Protective Equipment

	Positive-pressure (pressure-demand), self-contained breathing apparatus (NIOSH approved), or positive-pressure supplied air respirator with escape SCBA.
	Chemical resistant clothing (overalls and long-sleeved jacket, coveralls, hooded two-piece chemical splash suit, disposable chemical resistant coveralls.)
	Coveralls (under splash suit).*
	Gloves, outer, chemical resistant.
	Gloves, inner, chemical resistant.
	Boots, outer, chemical resistant, steel toe and shank.
	Boot-covers, chemical resistant (disposable).*
	Two-way radio communications (intrinsically safe).*
	Hard hat. *
	Faceshield.*

* Optional

LEVEL C

Level C protection should be selected when the type of airborne substance is known, concentration measured, criteria for using air-purifying respirators met, and skin and eye exposure is unlikely. Periodic monitoring of the air must be performed.

Personal Protective Equipment

	Full-face or half-mask, air-purifying respirator (NIOSH approved).
	Chemical resistant clothing (one piece coverall, hooded two piece chemical splash suit, chemical resistant hood and apron, disposable chemical resistant coveralls.)
	Gloves, outer, chemical resistant.
	Gloves, inner, chemical resistant.
	Boots, steel toe and shank, chemical resistant.
	Boot-covers, chemical resistant.*
	Cloth coveralls (inside chemical protective clothing).*
	Two-way radio communications (intrinsically safe).*
	Hard hat. *
	Escape mask. *
	Faceshield.*

* Optional 

LEVEL D

Level D is primarily a work uniform and is used for nuisance contamination only. It requires only coveralls and safety shoes/boots. Other PPE is based upon the situation (types of gloves, etc.). It should not be worn on any site where respiratory or skin hazards exist. Refer to The Office of Emergency and Remedial Response. Environmental Response, Division. See “Interim Standard Operating Safety Procedures” for full details.

The type of environment and the overall level of protection should be reevaluated periodically as the amount of information about the site increases and as workers are required to perform different tasks.

Reasons to upgrade to a higher level (D is lowest, A is highest)

	Known or suspected presence of dermal hazards
	Occurrence or likely occurrence of gas or vapor emission
	Change in work task that will increase contact or potential contact with hazardous materials
	Request of the individual performing the task

Reasons to downgrade:

	New information indicating that the situation is less hazardous than was originally thought
	Change in site conditions that decreases the hazard
	Change in work task that will reduce contact with hazardous materials

 

EFFECTIVENESS OF PROTECTIVE  MATERIALS  AGAINST CHEMICAL  DEGRADATION (BY GENERIC CLASS)
Generic Class	Butyl rubber	Polyvinyl chloride	Neoprene	Natural rubber
Alcohols	E	E	E	E
Aldehydes	E-G	G-F	E-G	E-F
Amines	E-F	G-F	E-G	G-F
Esters	G-F	P	G	F-P
Ethers	G-F	G	E-G	G-F
Fuels & Solvents	F-P	G-P	E-G	F-P
Halogenated Hydrocarbons	G-P	G-P	G-F	F-P
Hydrocarbons	F-P	F	G-F	F-P
Inorganic acids	G-F	E	E-G	F-P
Inorganic bases & salts	E	E	E	E
Ketones	E	P	G-F	G-F
Natural fats and oils	G-F	G	E-G	G-F
Organic acids	E	E	E	E

E = Excellent        F= Fair          G = Good      P = Poor