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I. STANDARD OPERATING PROCEDURES

A. Introduction to Safe Laboratory Practices

A number of rules for safe laboratory practice are outlined below. This listing is intended to provide a practical base line for laboratories required to handle hazardous chemicals. Because of the nature of specific chemical hazards, this list is not comprehensive, but it will help investigators to provide an appropriate safety plan for their laboratories.

The University Department of Occupational and Environmental Safety is available for consultation on all safety and health issues at 368-2906 (Radiation Safety) or 368-2907 (Chemical Safety Services).

1) General Safety

a) Be alert to unsafe conditions and actions and call attention to them so that corrections can be made as soon as possible. Safety is a community responsibility.

b) Post warning signs when unusual hazards such as radiation, lasers, flammable materials, infectious agents or other special hazards exist. Signs are to be posted on all entrances to the laboratory. Three panel signs are available from Safety Services. All laboratories must also be posted with emergency contact information. Make sure these signs are clearly visible.

c) Unauthorized personnel (minors and the general population) are prohibited in all laboratories.

d) Visitors in laboratories must be accompanied by faculty or staff members or a graduate student. Visitors must wear eye protection while in laboratories that may present a chemical or physical hazard.

e) No undergraduate laboratory classwork shall be carried out in the absence of an instructor. Unauthorized experiments and horseplay are prohibited. Unapproved variations in experiments, including changing the quantities of reagents, may be dangerous, and must be strictly guarded against in undergraduate laboratories.

f) DO NOT CARRY OUT HAZARDOUS PROCEDURES WHEN WORKING ALONE. This rule may be relaxed whenever there is another person within call.

g) Eating, drinking, chewing gum, applying cosmetics and hand lotion, and smoking are prohibited in laboratory areas.

2) Personal Protective Equipment

a) Clothing shall be appropriate to the laboratory--long pants and regular shoes, for example. Sandals or open-toed shoes, shorts, ties or other dangling clothing can pose a threat in the laboratory.

b) Lab coats, gloves, and other PPE shall not be worn outside the laboratory area.

c) Wear proper eye protection when working in a laboratory.

d) Contact lenses are a risk when working with hazardous chemicals. Particulate matter, vapors, and liquids can lodge behind the contact lenses and cause considerable eye damage before they can be washed out with water from an eyewash station. In addition, solvent vapors can weld contact lenses to your eyes, requiring surgery to remove them.

e) Select appropriate gloves when working with toxic or corrosive materials. Call the glove manufacturer or consult Appendix D for discussion of glove compatibilities. See Chapter II, Section B, for more information on glove selection.

f) Proper personal protective equipment must be worn at all times in the laboratory. Avoid direct contact with all chemicals. Keeping chemicals away from hands, face and clothing (including shoes or other foot-covering) is especially important. Many substances are readily absorbed into the body and through the skin, or may enter through the mouth because of contamination of the hands. In case of any accidental contact with chemicals, wash immediately with soap and water, but take care not to abrade the skin.

g) A change of clothing should be available in the laboratory in case of an accident.

3) Physical Housekeeping

a) Aisles and hallways shall have proper egress. (see glossary for definition)

b) Keep drawers and cabinets closed while working. Avoid slippery floors by picking up any ice, glass beads, glass rods, or other small items. Mop up any spilled water.

c) Keep workplace uncluttered--benches, desks, and tables are work areas, not storage space. Have only necessary materials (instructions, notebook, pen or pencil) at hand. Keep workplace free from extraneous chemicals and non-essential objects.

4) Safety With Chemicals

a) All heating of chemicals must be performed in a fume hood. Prior to heating a liquid, place boiling stones in vessels (other than test tubes). Use a thermometer in a boiling liquid if there is the possibility of a dangerous exothermic decomposition, as in some distillations. Explosions are one of the most serious physical hazards in the laboratory.

b) Never put your nose directly over a container to smell the contents.

c) Never look down the opening of a vessel unless it is empty.

d) Caution should be used when opening bottles on which the lid or stopper is stuck; for example, wrap the bottle with a towel and place it in a container before applying more force.

e) All containers containing hazardous chemicals must be clearly labeled with the contents of the container. Use the complete chemical name, not abbreviations (See Chapter Four, Section I, Part B).

f) Never use any substance from an unlabeled or inadequately labeled container. Any unlabeled containers should be disposed of according to the University Guidelines on Waste Disposal (See Chapter Four, Section I, Part B).

g) Flasks containing large volumes of toxic solutions, volatile solvents, boiling liquids and so forth, should be kept in pans large enough to contain the contents if the flask breaks. These should also be transported in appropriate transport containers.

h) All chemicals or biological material with an objectionable odor should be kept in the hood or in an appropriately vented safety cabinet.

5) Waste Disposal

a) Hazards to the environment must be avoided by following required waste disposal procedures (See Chapter Four).

b) Chemicals shall not be poured down drains. See Chapter Four for waste disposal procedures.

B. Laboratory Practices for Specific Procedures

1) Flammable Substances

a) Learn the location and the use of the nearest fire extinguisher.

b) A hood should be used for reactions in which flammable vapors are released, e.g., during the distillation of ether. If noxious or flammable gases are likely to be evolved in any process, the experiment must be confined to a fume hood behind an explosion shield. See Chapter Two, Section II, Subpart b for a complete discussion of fume hoods.

c) Ethers and other peroxide-forming chemicals should be dated when they are received and when they need to be disposed of. Ether should not be stored past the expiration date. Purchased ethers generally contain inhibitors to prevent the build-up of peroxides. Any distilled or processed ether no longer contains these inhibitors and should be used immediately or disposed of. Follow the disposal procedures for ethers described in Chapter Four.

d) Do not pour ether, petroleum, or other flammable water-immiscible liquids into sinks to be washed down with water. Fires and explosions have been caused in laboratories by vapors returning through the drainage system (e.g., during aspiration or rotary evaporation). See Chapter Four for general waste guidelines.

e) Set up and label special waste receptacles for paper and glass. Oily rags and other oil-impregnated materials shall be stored in an approved, covered metal container and disposed of by placing the container in the trash bin.

2. Reactive Substances

a) When conducting a reaction where there is any possibility of even a mild explosion, use a face shield that is sufficiently large and strong to protect the face and neck, or use a standing shield. Eye protection must be worn even when using a shield.

b) When sodium, potassium, or lithium are used, the cuttings or residual pieces must be properly disposed of immediately. Store any of these metals in kerosene, oil, toluene, xylene, or other saturated hydrocarbon.

c) Never leave chemical reactions which have not achieved kinetic equilibrium unattended.

3. Corrosive Substances

a) Always pour acid into water, never water into acid, as it can cause an exothermic reaction. For the same reason, pour concentrated solutions into water or less concentrated solutions while stirring.

b) Always rinse the outside of acid bottles before opening them. Do not put down a stopper from an acid bottle on a surface where a person may rest a hand or arm. Keep acid bottles tightly stoppered; rinse and dry them before replacing them on the reagent shelf. Make certain that no spills remain on tables, floor or bottle.

c) Bottles containing acids or other corrosive liquids shall be carried in the protective containers supplied for that purpose.

d) Use the proper techniques for inserting and removing a glass tube from a stopper. Protect your hands. Shortcuts can lead to a severe puncture wound.

4. Electrical Equipment

a) All electrical connections should be grounded.

b) Service cords for electrical equipment should be in good condition. Frayed cords or exposed wires should be repaired by qualified personnel.

c) Avoid overloading circuits. Do not use multiple outlet plugs for additional connections.

d) Do not handle any electrical connections with wet hands or when standing in or near water.

e) Do not use electrical equipment, such as mixers or hot plates, around flammable solvents.

f) Do not try to repair equipment yourself unless you are qualified and fully understand the repairs required. All repairs should be done by qualified personnel.

g) Never try to bypass any safety device on a piece of electrical equipment.

h) In case of a fire on or near any electrical equipment, turn it off if it can be done so safely.

5. Apparatus

a) Use pipetting devices. Do not mouth pipette chemicals.

b) Know the location of the nearest safety shower, fire extinguisher, fire blanket, eyewash station and clean-up kit to be used after a chemical has been spilled.

c) Apparatus attached to a ring-stand should be positioned so that the system's center of gravity is over the base and not to one side--the lower the better. Leave adequate room for removing burners or baths.

d) Equipment with moving parts (gears, belts, pulleys) must be equipped with protective guards.

e) Make sure all personnel who operate centrifuges are well-trained. Centrifuge tubes should be in good condition, with no chips or other flaws. Tubes and rotor buckets must be balanced when in use. Inspect the rotors periodically and do not use them beyond their stated lifetime.

f) Each water supply outlet within the laboratory must be equipped with either a vacuum breaker or a back flow prevention device. No auxiliary plumbing should be connected to a water distribution line unless adequate back-flow prevention is provided.

g) Secure all gas cylinders against walls or lab benches with safety straps or chains to prevent them from toppling over.

h) Use undamaged, clean glassware without chips or other flaws.

i) Dewar flasks should be taped when in use or enclosed in metal mesh to protect personnel from flying glass.

j) Glass devices in vacuum systems should be epoxy-coated, taped, or shielded with glass or wire mesh to protect personnel from fragmentation.

k) Sink traps and floor drains should be kept filled with water at all times to prevent escape of sewer gases into the laboratory. Such gases may be toxic or flammable and may be ignited, causing flash fires.

l) DO NOT USE or permit burners, hot plates, or non-explosion-proof motors near experiments which may generate flammable gases.

m) Use beaker covers to prevent splattering when heating liquids on a hot plate. Keep a pair of tongs conveniently at hand. A specific tong for the dish crucible, beaker, casserole or flask should be used.

n) In general, if apparatus is likely to shatter, either because of pressure or vacuum, surround it with mesh or cloth to limit the travel of shattered glass particles.

o) Glassware or any potential "sharps" (including chemical bottles and test tubes) should be set well back from the front edge of the work bench to lessen the risk of injury if there is an accidental breakage of glass.

p) Adequate traps must be used in vacuum systems. Do not release the vacuum in any apparatus when the temperature is above 150 degrees Celsius. The hot vapors may explode.

q) Oven temperature regulators should be checked periodically to ensure they are working reliably.

r) Bunsen burners should never be left burning when not in use. They should be turned off at the petcocks--do not depend upon the valve at the base of the burner.

s) Do not use natural gas in laminar flow or non-vented hoods.

II. PERSONAL PROTECTION: METHODOLOGY, ENGINEERING CONTROLS AND PERSONAL PROTECTIVE EQUIPMENT (PPE)

A. Introduction

Methodology, engineering controls and personal protective equipment are designed to address and prevent hazards associated with the introduction of chemicals into the body. The major routes of entry into the body are inhalation, skin absorption, ingestion, injection, and subcutaneous entry. Engineering controls that ventilate gases, vapors, and small particulates are designed to eliminate the hazards associated with inhalation, the major route of entry. Personal protective equipment (PPE) is designed to eliminate exposure through all above routes of entry.

Personal protective devices are to be used only where methodology or engineering controls cannot be used or while controls are being implemented.

B. Methodology

Methodological procedures are those incorporated into activities in order to eliminate or minimize the potential for exposure. These include:

• isolation of the operator or the process
• hazard education
• job rotation to limit exposure to hazardous substances
• substitution of less hazardous equipment or process (e.g. safety cans for glass bottles)
• substitution of a less hazardous substance

C. Engineering Controls

Engineering controls include tools or devices that limit exposure to a hazard:

• local and general ventilation (e.g. use of fume hoods)
• use of biological safety cabinets or glove boxes
• placing walls or increased distance between the operator and the hazard
• using appropriate disposal containers

1) Laboratory Ventilation

a) Control of Air Flow in the Laboratory

Safety in laboratory areas partially depends upon keeping infectious, toxic and flammable airborne materials away from personnel. Controlling air flow helps accomplish this.

b) Doors to Laboratories

In general, doors to laboratories should remain closed. When the air flow is correctly balanced, air pressure in the corridor is higher than in the laboratories and the air flows under the doors and through the door slots into the laboratory. This moving curtain of air keeps airborne substances generated in the work areas from entering the corridors.

2) Chemical Fume Hoods

a) General

Hoods offer two significant types of protection from atmospheric exposure to hazardous materials:

i) local ventilation to prevent toxic, offensive, or flammable vapors from entering the room.

ii) a physical barrier between the researcher and the chemical reaction when that reaction is performed in a hood, especially with the hood sash closed. This barrier can protect researchers from hazards such as chemical splashes or sprays, fires and minor explosions.

Hoods should be considered primary safety devices that can contain and exhaust toxic, offensive, or flammable materials when the design of an experiment fails and dusts or vapors escape from the apparatus being used. Hoods should never be used as a means of disposing chemicals.

A properly functioning hood should have an average face velocity of at least 100 linear feet per minute (lfm) at a sash height of 25 inches or greater.

Chemical fume hoods are tested at least annually by Safety Services. If you need assistance or more information about a chemical fume hood in one of your laboratories, or if your fume hood is not posted with a label showing that it has been tested in the last year, please contact Safety Services at x2907.

NOTE: Use perchloric acid in a specifically designated fume hood. DO NOT use other chemicals in that hood. Clearly mark that the fume hood is for use only with perchloric acid.

b) Safe Hood Work Practices

i) Keep work surfaces clear

ii) Make sure the exhaust blower is operating and air is entering the hood prior to starting an experiment.

iii) Periodically check air flow through the hood using a source of visible smoke or other air flow indicator, such as a Kimwipe. If there is a problem with air flow, call Plant Services (x2580). Plant Services will notify Safety Services if necessary.

iv) Do not disable flow measurement devices or alarms.

v) Work with the sash at the proper operating level as indicated by Safety Services test arrows.

vi) Do not place your face inside of the hood. Keep hands out as much as possible.

vii) Keep sources of emission at least six (6) inches inside the hood.

viii) Do not store chemicals in the hood. Clean up all minor spills immediately.

ix) Avoid blocking the baffle exhaust slots in any manner. Keep large equipment two (2) inches off the base of the hood and two inches from the sides of the hood.

x) Be aware of other room ventilation factors that may interfere with your hood operation, such as open doors, open windows, blocked exhaust ports or heating and air conditioning vents.

xi) Avoid cross drafts and disruptive air currents in front of the fume hood.

xii) Use the sash as a safety shield when boiling materials or conducting an experiment with reactive materials.

xiii) Close the fume hood sash when the fume hood is not in use.

3) Use of Laminar Air Flow Equipment

*note: Laminar flow hoods are not safety devices. If biological safety is an issue with your work, use a biosafety cabinet with or without glove attachments as warranted by the experiment. Biosafety cabinets include 100% exhaust laminar flow hoods and glove boxes with chemical traps or exhaust access to a fume hood.

Laminar flow equipment will be leak tested, adjusted or repaired by a certified contractor such as MicroClean.

Two types of laminar flow equipment, the laminar flow clean bench and the biological hood, are discussed in this section.

a) Laminar Flow Clean Bench

The laminar flow clean bench protects the product from airborne contamination, but does not protect the operator. Because of the risk to personnel, work with hazardous material on a laminar flow clean bench is not advisable. Use of clean benches should be limited to the preparation of sterile media, the assembly of sterile components into complete units (e.g., membrane filters), the examination of sterilized equipment and materials for possible contamination, and similar operations. Work with pathogens is not permitted.

A large number of companies manufacture both vertical and horizontal laminar flow clean benches. Most of the commercially available equipment is adequate when:

• The High Efficiency Particulate Air (HEPA) filter has been tested and certified. To meet standards, this filter should be at least 99.97 percent efficient in removing particles 0.3 microns or larger by the di-octylphthalate (DOP) test.
• The HEPA filter housing has been properly sealed around the edges to prevent unfiltered air from bypassing the filter.
• The air flow is adjusted to 80-100 linear feet per minute.
• The pre-filter is periodically cleaned or replaced when the magnahelic gage indicates it is full because of a pressure drop.

b) Biological Hood

The biological hood protects both product and operator and may be used for organisms which exceed biosafety level 2. (See CDC/NIH publication Biosafety in Microbiological and Biomedical Laboratories, 3rd ed, USDHHS, 1996, for a list of organisms and applicable biosafety levels. Check their website for information: http://www. cdc.gov/ods/ohs). Safety and desirability of using this equipment to contain infectious material should be determined on an individual basis, depending upon the agent, the proposed activity, and the need to prevent cross-contamination. This hood, however, cannot replace the standard gastight Class III biological safety cabinet for extremely hazardous work.

D. Personal Protective Equipment (PPE)

Along with engineering controls and carefully planned workplace methodology, personal protective equipment (PPE) is the key element in minimizing the potential for worker exposure to chemicals.

Proper use of PPE requires that the supervisor assess the hazard presented and attempt to apply engineering controls and/or administrative controls first. PPE is used when engineering controls and/or administrative controls will not be effective.

The performance of PPE as a barrier to chemicals is determined by the materials and quality of its construction. Three important factors to keep in mind when considering PPE are:

1) in general, there is no such thing as "impermeable" plastic or rubber clothing;

2) no one clothing material will be a barrier to all chemicals;

3) for certain chemicals or combinations of chemicals, there is no commercially available glove or clothing that will provide more than an hour's protection following contact. In these cases, it is recommended that PPE be changed frequently or as soon as it comes into contact with the chemical or mixture.

Of principal importance in the selection of PPE for protection from chemicals is the rate at which chemicals permeate clothing materials and the time elapsed between the contact with the chemical and the appearance of the chemical on the inside of the PPE, called breakthrough time.

1. Respirators

The basic purpose of any respirator is to protect the respiratory system from inhalation of hazardous atmospheres. Respirators provide protection either by removing contaminants from the air before it is inhaled or by supplying an independent source of respirable air.

Safety Services has implemented a comprehensive Respiratory Protection Program. This training involves taking a physical exam at Health Services and getting properly trained and fit-tested with a respirator. Refer to the CWRU Respiratory Protection Program Document or call 368-2907 for further information.

2. Gloves and Lab Coats

a) Gloves

Gloves are a type of PPE that should be used frequently, selected on the basis of chemical compatibility (see Appendix D). In general, latex gloves do not provide adequate protection and are not recommended for any chemical operations.

Reusable gloves that are readily available on campus include:

• Neoprene - Provides protection against a broad range of corrosive chemicals. Resists oils, greases, alcohols, resins, alkalis, and many solvents. Neoprene is poor for chlorinated aromatic solvents, phenols, and ketones.
• Nitrile-Butadiene Rubber (NBR) - Marketed as SOL-VEX or Nitrile. Work well in aromatic petroleum and chlorinated solvents. Resistant to cuts, snags and punctures.

Contact Safety Services or refer to the glove compatibility table listed in Appendix D for the best glove for your operation.

b. Lab Coats

Lab coats should always be worn during active work in the laboratory. They should be buttoned to protect more completely. Lab coats are loose-fitting by design, so that in case of chemical contact there is ample time to react before the chemical gets to the undergarments and ultimately to the skin. They should not be taken home or taken home to be washed; instead arrangements should be made in the lab group for laundry service.

3. Eye Protection

This guide defines eye-hazard areas where wearing eye-protective equipment is mandatory. It also sets forth the supervisor's responsibilities, both in identifying locations where possible damage to the eyes could occur and in enforcing precautionary procedures in these areas.

The Occupational Safety and Health Act of 1970 and good safety practices dictate that "protective eye and face equipment shall be required where there is a reasonable probability of injury that can be prevented by such equipment--suitable eye protectors shall be provided where machines or operations present the hazard of flying objects, glare, liquids, injurious radiation, or a combination of these factors."

The type of eye protection required depends on the hazard. For most situations, safety glasses with side shields are not adequate. Where there is danger of splashing chemicals, special non-ventilated sealed goggles are required. For more hazardous operations, a face shield or a combination face shield and safety goggles or glasses (some of which may be supplied with prescription lenses) should be used. Failure to wear the prescribed eye-protection equipment will be grounds for disciplinary action. Safety Services will assist in the choice of suitable protective equipment.

a) Special Hazards

Contact lenses shall not be worn by persons exposed to hazardous chemicals. It is the responsibility of supervisors to identify employees who wear contact lenses. Contact lenses do not provide eye protection. The capillary space between the contact lenses and the cornea may trap material present on the surface of the eye. Chemicals trapped in this space cannot be washed off the surface of the cornea. If the material in the eye is painful or the contact lens is displaced, muscle spasms will make it very difficult to remove the lens.

Supplies of caustic chemicals, e.g. ammonia solution, liquid phenol, acids, strong bases, etc., should be stored no higher than countertop level to minimize the possibility of facial and upper body burns in the event of spills or breakage of containers. It is also a good practice to use the smallest size container compatible with the need.

b) Eyewash Facilities

Emergency eyewash facilities shall be available in areas where:

• Corrosive or caustic materials are handled
• Explosive materials are handled
• Hollow glassware is under vacuum or pressure
• Cryogenic materials are handled
• Flying particles may be generated (grinders, mills, power saws, drill presses, lathes, etc.)
• Molten metal is used or metal is melted (soldering, leading joints, etc.)
• Gas or electric arc welding is done
• Processes can produce aerosols of infectious agents
  (e.g., removing lyophil vials from liquid nitrogen)

c) Supervisor's Responsibilities

i) The supervisor is responsible for:

• Determining that an eye hazard exists
• Placarding the work area with proper signage
• Determining the type of eye protection equipment needed
• Obtaining necessary assistance from Safety Services
• Ensuring that the equipment is available to employees
• Ensuring that the necessary personal protective equipment is worn by employees
• Suppying all PPE as necessary

ii) Failure of the supervisor to enforce eye-protective requirements will be grounds for disciplinary action.

If you have a condition which requires special consideration, please contact Safety Services (x2907).

III. CHEMICAL STORAGE

A. General Rules

Contact Safety Services for any assistance.

1) Keep minimum quantities of chemicals in the laboratory. Purchase only what is needed. Never acquire more than a year's supply of reactive or combustible chemicals.

2) Chemicals shall be stored in cabinets or on shelves. Long-term storage of chemicals on the floor, on benches, or in hoods is discouraged. Liquids should be stored below eye level.

3) Use spill trays under containers of strong reagents. Perchloric acid should be kept on glass or ceramic trays of sufficient capacity to hold all of the acid in case of breakage.

4) Do not store chemicals past their expiration date. Ethers, for example, generally contain inhibitors to prevent the build-up of peroxides. Any distilled or processed ether no longer contains any inhibitors and should be used immediately or disposed of. Follow disposal procedures for ethers described in Chapter Four.

5) Store chemicals according to compatibility. Within compatible classes, chemicals may be stored alphabetically. See Appendix E for a table of incompatible chemicals or consult your MSDS.

6) Label all containers (new bottles as well as temporary containers) properly. Information that should be on the container is as follows: your name, PI , date, contents, purity, location, hazards (if known).

7) Dispose of unwanted chemicals promptly. See waste disposal procedures, Chapter Four, Section A).

B. Storage of Flammable Solvents

1) Policy

This guide establishes policy and describes cabinets for storing flammable solvents in the lab. In this guide, flammable solvents are defined as liquid substances having a flash point below 140_ F and having a vapor pressure not exceeding 40 p.s a. at 100_ F.

The following items will be stored in National Fire Protection Association (NFPA)-approved solvent storage cabinets:

a) All containers of flammable solvents larger than one half-gallon.

b) All flammable solvent supplies, when cumulative amounts of greater than two gallons are kept in one laboratory room.

2) Storage Cabinets

Several sizes of cabinets are manufactured, allowing a choice to fit funds and available space. Many laboratories may require storage of only a few solvents and the supervisors may wish to share cabinets with adjoining laboratories.

Commercially manufactured flammable solvent storage cabinets are sold by several laboratory supply firms. These larger boxes hold either 30 or 45 one-gallon containers. Safety Services can advise on NFPA-approved cabinets.

Laboratory supervisors should determine their storage needs and order appropriately sized cabinets.

IV. CWRU HAZARD WARNING SIGNS

In an effort to bring the system of signs used at Case Western Reserve University into agreement--to warn of danger and to direct "pedestrian traffic" away from laboratory work areas-- uniform hazard warning signs have been designed. This guide describes the signs and sets forth the conditions under which the signs are to be posted. It is important that all employees and visitors comply with the policy for entering areas where these signs have been posted.

A. Description

Samples of commonly used warning signs are illustrated in Figure 2. The signs inform employees and visitors that a hazard exists in an area. The degree of danger is indicated by the sign. In high risk areas, admission is forbidden to all except those assigned to that area. In lower risk areas, visitors must secure permission to enter from the investigator in charge of the work.

B. Policy

The investigator in charge of the laboratory is responsible for posting the signs in accordance with policy set forth in this guide. Upon request, Safety Services will assist investigators in determining the need for posting warning signs.

The signs will be posted only while a hazard exists and must be taken down as soon as the source of danger is removed. Hazard signs will not be posted when no hazard exists simply to discourage traffic through an area.

At the end of working hours, decontaminate laboratory work areas so that janitors, plant personnel, firefighters and others can safely enter the areas. If this is not done, post a special "DANGER--DO NOT ENTER" sign. Hazard warning signs will show the name of the hazard(s), the investigator and an alternate, and their home telephone numbers. When appropriate, similar signs will be posted on both the laboratory and animal holding rooms.

The investigator named on the hazard sign will determine when visitors can be allowed in the laboratory. He or she is responsible for their safety while they are there. Visits are restricted to those who have a need to observe laboratory procedures. Social visits by staff and visitors are prohibited in areas where biohazards are present.

C. Methods of Posting

Signs that are to be used permanently will be posted only in permanent frames. The investigator in charge of the laboratory is responsible for requesting the installation of the frames. Signs that are to be used on a temporary basis (less than one month) will be posted in permanent frames if such frames have been installed. If frames have not been installed, these signs will be posted with masking tape on a glass surface or, if more appropriate, on refrigerators, freezers, doors, etc.

Signs will not be posted with tacks, pins, or any adhesive material that would damage the doors, walls, or building when the signs are removed.

D. NFPA Signage

The Occupational Safety and Health Administration has adopted NFPA signage to indicate the hazards present in a given location. The NFPA diamond, as shown in Figure 3, contains four (4) sections as described in the diagram. Each of these sections contains a number from zero (0) for no hazard to four (4) indicating the highest possible hazard. These signs shall be posted outside each laboratory and shall be filled in with the information on the highest possible hazard which is present in each room.

E. Availability of Signs

The investigator in charge of the laboratory is responsible for securing the appropriate signs and frames. These are available through most laboratory supply companies. Most commonly used signs are available from Safety Services.