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Any workplace has the potential to expose workers to harmful substances; however, within a laboratory, the probability that an individual is exposed to hazardous materials is significantly greater. To ensure the protection of all laboratory workers, all principal investigators and other laboratory supervisors are responsible for providing their employees with the most suitable protective equipment. This must abide by the Control of Substances Hazardous to Health (COSHH) law.
What is COSHH?
Under the direction of the Health and Safety Executive, Control of Substances Hazardous to Health (COSHH) is a United Kingdom Statutory Instrument that requires employers to ensure the safety of their workers who may be exposed to hazardous substances. In terms of preventative health measures, the COSHH requires that employers are aware of any potential health hazards that can result from exposure to hazardous substances that may be found in the workplace.
With this knowledge, employers are expected to provide adequate control measures to their employees that can prevent unwanted exposure to these substances. Furthermore, employers are expected to periodically confirm that these products are in good working order and are being used appropriately by their workers.
COSHH in the Laboratory
Nearly any type of work environment can contain potentially hazardous materials in which workers can be exposed to. Since individuals who work in laboratories typically work with chemicals and other potentially harmful agents, the COSHH requirements must be followed.
Personal Protective Equipment
Personal Protective Equipment (PPE) refers to any type of safety equipment that can be worn by workers when working with hazardous substances. Depending upon the activity or task, different PPE will be required. For example, individuals who are working with highly reactive or explosive chemicals can potentially be cut by glass or other material fragments if the hazardous substance causes an explosion. Additionally, an explosion can cause chemicals to be released and thereby contaminate the eyes, face, hands and/or body of the worker.
To protect oneself from such an event, it is recommended that the worker only handles the hazardous substance under a chemical fume hood. To prevent unwanted chemical contamination, the worker should use goggles, a face shield, utility-grade gloves and a flame resistance lab coat when handling this substance.
Laboratory Fume Hoods
A chemical fume hood, which can also be referred to as a laboratory fume hood, is one type of engineering control that is used to reduce the exposure of laboratory workers to potential hazards, such as flammable and/or toxic chemical agents. The two main types of fume hoods found in any laboratory include a ducted fume hood or a ductless fume hood.
Regardless of the type of chemical fume hood being used, air is pulled from the room and enters the sash, which separates the internal compartment of the hood from the external work area. As air is pulled into the hood, it enters the center and pushes out any harmful gases, vapors and fumes, all of which may be released from chemicals being handled in the hood, into the exhaust area.
Depending upon the type of chemical fume hood being used, the exhaust area will contain several slots and baffles that allow the circulating air to make its way into the connected ductwork or fume hood filters. Once air exits the ducted fume hood, it will eventually be released into the atmosphere, whereas ductless fume hoods will filter the collected air and ultimately recirculate it back into the room where the hood is located.
Although both a chemical fume hood and a biological hood can both be referred to as “hoods,” these two engineering controls function very differently. For example, fume hoods primarily provide personnel protection, whereas biological hoods, which can also be referred to as biosafety cabinets, provide environmental, worker and product protection.
Even though all biosafety cabinets will utilize High Efficiency Particulate Air (HEPA) filtration systems, there are three different types of biological hoods, including Class I, Class II and Class III. The biosafety level (BSL) of the substances being handled by the laboratory worker will dictate the appropriate class of biosafety hood required. For example, individuals who are handling BSL 4 agents like the Ebola virus must always use a Class III biological hood when handling these substances.
In a similar mechanism to that which is used in chemical fume hoods, Class I biological hoods will pull in the air away from personnel in the work area. Class II biosafety cabinets, on the other hand, will not only withdraw air from the laboratory worker but will also provide a steady flow of sterile air over the workplace within the cabinet. The exhaust air within a Class II hood can be recirculated by HEPA filtration or released into the atmosphere. Class III biological hoods are gas-tight enclosures that utilize the HEPA filtration system to purify both intake and exhaust air.
References and Further Reading