PHYSICAL CONTAINMENT LEVELS
Four levels of containment (1-4) appropriate to the four risk groups for infectious agents are defined below. These levels of containment are to be regarded as adequate for most laboratory uses of the particular agents. It remains the responsibility of the principal investigator or laboratory director and the institution to require a higher level of containment for specific manipulations, if these appreciably increase the hazard of infection.
5.1 CONTAINMENT LEVEL 1
This level applies to the basic laboratory for the handling of Risk Group 1 agents. Containment Level 1 (CL1) requires no special design features beyond those suitable for a well designed and functional laboratory. Biological safety cabinets are not required. Work may be done on an open bench top and containment is achieved through the use of practices normally employed in a basic microbiology laboratory.
5.1.1 PHYSICAL REQUIREMENTS
§ A room separated from public areas by a door is required. There are no particular restrictions on locating the facility near public or heavily travelled corridors; however, doors should remain closed.
§ Coatings on walls, ceilings, furniture, and floors should be cleanable. Windows that can be opened should not be near working areas or containment equipment and should be equipped with fly screens.
§ There are no special air handling requirements beyond those concerned with proper functioning of the biological safety cabinets, if used, and those required by building codes.
§ Handwashing facilities must be provided, preferably near the point of exit to public areas.
§ Separate hanging areas should be provided for street clothing and laboratory coats.
§ Eye wash stations may be required by local statute.
5.1.2 OPERATIONAL REQUIREMENTSBasic safety practices as described in Chapter 2 must be followed.
In addition, where chemical disinfection procedures are practised, effective concentrations and contact times must be employed. Chemical disinfectants used to decontaminate materials to be removed from the laboratory must be replaced regularly.
5.2 CONTAINMENT LEVEL 2
Containment Level 2 (CL2) is suitable for work with agents in Risk Group 2. In addition to the requirements of containment Level 1, the following are required:
5.2.1 PHYSICAL REQUIREMENTS
§ The laboratory should be located away from public areas, general offices, and patient care areas.
§ A biohazard sign with appropriate information must be posted on the entrance to the laboratory.
§ Laboratory furnishings and work surfaces should be impervious and readily cleanable.
§ Coat hooks must be provided for laboratory coats near the exit.
§ An autoclave must be available in or near the laboratory.
§ Laboratory doors should be self-closing.
5.2.2 OPERATIONAL REQUIREMENTS§ Class I or II biological safety cabinets (see Appendix B) are required for all manipulations of agents which may create an aerosol. The biological safety cabinet must have been tested and certified within the previous 12 months according to accepted standards (see Appendix B).
§ Air from these cabinets may be recirculated to the room only after passage through a high efficiency particulate air (HEPA) filter.
§ Centrifugation must be carried out using closed containers or aerosol proof safety heads or cups. These should be opened only in the biological safety cabinet described above.
§ Animals or insects which have been experimentally infected must remain in the laboratory or appropriate animal containment facility.
§ An emergency plan for handling spills of infectious materials must be developed and be ready for use whenever needed. Laboratory workers must be educated and drilled in the emergency plans.
§ Vacuum lines used for work involving the agent must be protected from contamination by HEPA filters or equivalent.
§ A laboratory coat to be worn only in the laboratory area is required. Coats that fasten on the front are permissible. These coats shall not be worn outside the containment laboratory.
§ Special care should be taken to avoid contamination of the skin with infectious materials; gloves should be worn when handling infected animals or when skin may be exposed to infectious materials.
§ Contaminated glassware must not leave the facility; decontamination must be carried out using procedures demonstrated to be effective. If there is no autoclave or incinerator in the laboratory, contaminated materials must be disinfected chemically or double bagged and transported to the autoclave or incinerator in durable, leakproof containers which are closed and wiped on the outside with disinfectant before leaving the laboratory.
§ Service personnel and cleaning staff who enter the facility must be informed of the hazards that might be encountered. Cleaning staff should clean only the floors. The laboratory personnel have the responsibility for rendering the facility safe for routine cleaning. Periodic intensive cleaning must be done at regular intervals. Cleaning and maintenance staff should receive appropriate immunization and medical surveillance if appropriate.
5.3 CONTAINMENT LEVEL 3Containment Level 3 (CL3) is suitable for work with agents in Risk Group 3. The operational requirements for the Level 3 laboratory are substantially greater than those for Levels 1 and 2 and the laboratory staff must receive specific training in the safe handling and manipulation of the agents used in this laboratory. Because the laboratory is designed to minimize environmental release of hazardous materials and provide enhanced worker protection the containment level 3 laboratory must undergo annual performance, testing and verification (see 7.8).
A Level 3 containment laboratory requires specialized design and construction. Those responsible for biosafety in an institution should maintain close control and seek expert advice and remain in close communication for all phases of design, construction, performance, verification and testing, operation and maintenance, and annual testing.
5.3.1 PHYSICAL REQUIREMENTS
The following are required in addition to the requirements for containment level 1 and containment level 2.
§ The laboratory must be located away from general work areas and have controlled access from other areas. This is accomplished by entry through a lockable changing room with self-closing doors. A body shower should be provided within the containment perimeter.
§ The laboratory must be held at a negative pressure relative to the surrounding areas at all times such that a directional airflow is created by air ingressing through all entry and exit areas. The laboratory should be provided with a dedicated supply and exhaust system which is sealed. The air discharged from the laboratory cannot be recirculated back into either the air supply system of the laboratory itself or into the building or adjacent buildings. Provided there is a dedicated sealed exhaust system, air may be exhausted from the laboratory to the exterior of the building without HEPA filtration. At the discharge point the exhausted air must be dispersed away from air intake or populated areas. However, when the air is not exhausted by means of a dedicated exhaust system, it must be passed through a HEPA filtered exhaust before discharging into the main building exhaust air ventilation system. This exhaust housing must be designed to allow in situ decontamination and must pass annual testing and certification by aerosol challenge and scan techniques. A control system must be provided to ensure that the Level 3 laboratory does not become positively pressurized relative to the surrounding area. When the supply air is not provided by a dedicated system, air-tight back draft dampers or HEPA filters must be installed in the supply system. The supply must be interlocked with the exhaust system.
§ Biological safety cabinets must be installed in a manner which does not interfere with the air balance of the cabinet or room. Thimble unit connections are recommended (see Appendix B).
§ The laboratory must have a dedicated handwashing sink with foot, knee or automatic controls, located near the exit.
§ The laboratory must have a pass-through or stand alone autoclave located in the work zone. Where physical constraints preclude the installation of an autoclave, in an existing level 3, alternative technologies may be used for sterilization of contaminated materials.
§ Laboratory furnishings should be kept to a minimum. Work surfaces should be impervious, readily cleanable, and resistant to chemical disinfectants.
§ All penetrations for services in the floors, walls, and ceiling of the laboratory must be sealed. The air supply/exhaust system should be provided with manual dampers at the room perimeter that may be closed as required to permit gas decontamination.
§ Water supplied to the laboratory must be provided with reduced pressure back flow preventers.
§ HEPA filters or equivalent should be provided on all ventlines.
§ Dunk tanks may be provided at the containment perimeter.
§ Sink and floor drains from this suite should be piped separately to the main building drain and be appropriately labelled. Floor drains are not generally recommended. Infectious materials must never be placed in sinks or floor drains.
§ Autoclave condensate drains should have closed connections and go directly to sanitary sewer.
§ In animal care facilities for small animals, the disposal of wastes will not differ from other contaminated laboratory materials. Large animals producing quantities of infectious wastes require special facilities which must be designed accordingly.
§ Portable vacuum pumps must be fitted with in-line HEPA filters or equivalent equipment. No vacuum lines may exit the containment perimeter.
§ Laboratory windows must be sealed and unbreakable.
§ Backup power should be provided to critical items such as biological safety cabinets, fume hoods , freezers etc.
5.3.2 OPERATIONAL REQUIREMENTSThe following are required in addition to those stated for CL1 and CL2:
§ Laboratory staff must be fully trained in the handling of pathogenic and other hazardous material and in the use of safety equipment, disposal techniques, handling of contaminated waste, and emergency response.
§ Staff are required to change into dedicated solid front laboratory clothing on entry to the facility. This laboratory clothing must be removed on completion of work and autoclaved prior to laundering.
§ Personal protective clothing, which may include head covers and dedicated shoes or impervious foot covers must be used while in the containment facility and removed on leaving.
§ Appropriate respiratory protection should be considered depending on the infectious agents in use.
§ Showers may be required depending on infectious agents used and manipulations involved.
§ Personal effects may not be taken into or stored in the laboratory.
§ Gloves must be worn when handling infective or potentially infective materials, including animals or waste.
§ All activities involving infectious materials are conducted in biological safety cabinets or other appropriate combinations of personal protective and physical containment devices.
§ Centrifugation must be carried out in closed containers using aerosol proof safety heads or cups which are loaded and unloaded in the biological safety cabinet.
§ Effective disinfectants must be available at all times in the laboratory.
§ All Risk Group 3 agents must be stored within the containment level 3 facility.
§ An effective pest control program must be in effect.
§ Written protocols must be provided and posted within the laboratory outlining operational protocols, waste disposal, disinfection procedures, and emergency response.
§ The facility must have a medical surveillance program appropriate to the agents used which includes serum storage for all personnel working in the containment laboratory.
§ The laboratory must have a reporting system for accidents and exposures to infective agents or other incidents or unusual occurrences in the operation of the laboratory.
§ Authorized maintenance and service personnel must abide by the same operational protocols as laboratory staff and be accompanied by laboratory personnel when entering and working within the laboratory.
§ The containment level 3 facility and its systems must be tested for containment capability upon completion of construction and at least annually thereafter (see 7.8).
5.4 CONTAINMENT LEVEL 4 The physical and operational requirements of containment level 4 are highly specialized and any Institution undertaking level 4 work must seek experienced assistance in developing the lab design and operational protocols.
Containment Level 4 is the highest level of containment and represents an isolated unit functionally independent of other areas.
This level of containment requires an air lock for entry and exit, Class III biological safety cabinets or positive pressure ventilated suits, a laboratory support area, and a separate ventilation system in addition to the physical and operational requirements of containment levels 1 to 3.
5.4.1 PHYSICAL REQUIREMENTS
§ The laboratory must be physically separated from other laboratories or consist of an isolated zone which is monolithic in construction with all penetrations to floors, walls, and ceilings sealed with non-shrinking sealant.
§ The laboratory must be designed to accommodate a minimum of two persons at all times, all laboratory equipment, long term storage of cultures and maintenance of infected animals.
§ Entry must be through an airlock system with doors that are electrically interlocked. Manual alarm overrides must be provided.
§ Change rooms must be contiguous with the containment perimeter of the structure and have a personnel shower and /or chemical shower (depending on the mode of operation).
§ All drain traps must be kept filled with an effective disinfectant and connected to a liquid waste effluent system.
§ All air access to any sewer and ventilation lines must be fitted with HEPA filters or equivalent.
§ All gas services must be fitted with HEPA filters, equivalent equipment, or back-flow preventers to prevent egress of contaminated material.
§ The water supply systems for the laboratory must be provided with back-flow preventers.
§ All windows must be sealed and provided with break-resistant glass.
§ The laboratory must be provided with a double-door autoclave preferably serviceable from outside the facility. The autoclave should have read-out charts inside and outside the containment laboratory and have operating controls inside the laboratory.
§ Dunk tank(s) which are chemically resistant and of a suitable size for the passage of anticipated laboratory materials may be required for Class III cabinet lines laboratories.
§ A dedicated handwashing sink with foot, knee or automatic controls must be located at the exit of each laboratory room in the containment level 4 laboratory (not applicable for suit laboratory).
§ The facility must be equipped with a two-way intercom system.
§ A closed circuit television system should be considered.
§ All liquid effluents from the facility must enter a waste effluent treatment system for sterilization which is mechanically and biologically monitored.
§ The facility must be ventilated by an independent, dedicated, sealed supply and exhaust air system which is not recirculated. Exhaust air must be passed through at least 2 HEPA filters mounted in series in sealed housings designed to allow in situ decontamination and testing by aerosol challenge techniques. Supply and exhaust ventilation systems must be designed to maintain directional (inward) airflows and pressure differentials, and interlocked to prevent pressurization in the event of exhaust fan failure. The supply air system must be equipped with a HEPA filter. The facility must be fully equipped with manometers and/or other monitoring devices and audible and visual alarms capable of being monitored by both laboratory and maintenance staff.
§ The laboratory must be provided with Class I, II or III tested and certified biological safety cabinets which must be installed in a manner that does not interfere with the air balance of the cabinet or room.
§ If a positive-pressure-ventilated-suit type of operation is used, a life-support system with full alarming, backup breathing air, emergency power and a chemical shower facility are required. Positive-pressure suits must be used whenever agents are worked with outside a Class III cabinet.
§ Alarms, ventilation and other critical systems must be on separate electrical circuits with emergency backup.
§ A laboratory support area should be provided adjacent to the Level 4 containment facility for all non-hazardous laboratory manipulations.
5.4.2 OPERATIONAL REQUIREMENTS§ Only fully authorized personnel may enter the Level 4 containment laboratory. A logbook (signed by all personnel) or electronic entry record must be maintained.
§ At all times when work is undertaken in the laboratory, there must be a competent person available outside containment who will be able to assist in case of emergency.
§ Protective clothing, gloves, and impermeable footwear are required. No street clothing will be worn under the protective clothing. On exit from the area, personnel will shower and re-dress in street clothing.
§ Small laboratory animals or insects under experimentation must be held in this area in ventilated cabinets having all output air HEPA filtered.
§ Large animals require specialized care and handling not dealt with by these guidelines.
§ All level 4 agents must be stored within the containment zone.
§ All materials shall be removed from the contaminated zone through an autoclave or placed in a double, unbreakable, sealed container, the outside of which will be disinfected. Where equipment and apparatus are not compatible with heat sterilization, materials may be removed via dunk tanks or air locks with suitable decontamination procedures.
§ All manipulations with agents in containment Level 4 must be performed in Class III biological safety cabinets (see Appendix A) or in Class I or II biological safety cabinets used in conjunction with one-piece, positive-pressure-ventilated suits.
§ Contingency plans for emergencies which may include responses to biological, toxic or hazardous spills, fire, or life-threatening situations must be prepared, and reviewed by all personnel.
§ A written reporting system for laboratory accidents and exposures must be in effect. A serum storage program for all laboratory and support personnel and a full medical surveillance and treatment program must be implemented.
§ The Level 4 facility and its systems must be tested for containment capability upon completion of construction and annually thereafter (see 7.8).
5.5 ANIMAL BIOHAZARD CONTAINMENT FACILITIESLaboratory facilities must provide containment for laboratory animals exposed to or harbouring infectious agents which is appropriate to the risk level of the infectious agents involved. In addition to the physical requirements identified in Sections 5.1 to 5.4, special equipment (e.g. filter cages, partial or isolation caging systems) appropriate to the animal species as well as to the level of risk must be used.
Operational procedures for the care and maintenance of the infected animals must satisfy the Guidelines of the Canadian Council on Animal Care (ref. 10) as well as the Laboratory Biosafety Guidelines in order to ensure not only protection for laboratory personnel and the environment but to ensure that every care is taken to avoid causing the animals unnecessary pain or suffering and to provide the animals with the highest quality care.
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