Hot and Bothered
By Jason Contant
By Jason Contant
Emergency responders who are tasked with cleaning up spills need apparel that provides all-rounded protection from the substances they are trying to remediate as well as suit the conditions in which they work. But how can workplaces that require head-to-toe protection ensure they make the best choice?
A good starting point is to identify any chemicals that a worker may encounter, says Jason Riesberry, director of global operations development for Lakeland Protective Wear Inc. in Brantford, Ontario. Consideration of the work process is also critical. A coverall and apron may suffice for laboratory work, but a higher degree of protection is needed if that task is changed to tank cleaning where workers may be surrounded by a chemical or substance that is coming at them from all angles. A third consideration is how long a worker will remain in the hazardous environment as some chemicals may permeate a protective fabric in 30 minutes, he says.
But that half-hour of protection will hardly suffice if the task is cleaning up a larger spill. A review of chemicals is important, but so is considering heat or cold stress, slips and falls, cuts, abrasions or punctures, electrical arcs and flammable, explosive atmospheres, suggests Dr. James Zeigler, Ph. D., a consultant with J. P. Zeigler, LLC in Richmond, Virginia. “People have a chemical hazard and they get tunnel vision around the rest of the hazards that are present.”
Riesberry estimates that 99 per cent of chemical clothing is thermal plastic material, which could “melt and drip and cause more damage” if exposed to heat and flame.
Many lightweight chemical suits are made of polyethylene and polypropylene, both of which are not appropriate in high-heat environments, Dr. Zeigler adds.
Industry has come up with its own way to classify hazmat protective clothing: levels A to D. Level A gear is needed when environments pose the greatest risk of respiratory, eye or skin damage from hazardous vapours, gases, particulates, sudden splash, immersion or contact with hazardous materials, notes information from the Occupational Safety and Health Administration in Washington, D.C. It involves encapsulation in a vapour-tight chemical suit and the use of a self-contained breathing apparatus (SCBA) or supplied-air system.
A full protective package will be necessary “if you don’t know what you’re dealing with,” Riesberry says. Once the environment has been assessed and any hazards mitigated, a decision can then be made about “whether you need to stay in a Level A or you can downgrade yourself into more comfortable garments.”
If the work area demands the highest degree of respiratory protection, but less so for skin protection, Level B would be the gear of choice. This type of gear typically does not provide protection from vapours, but does require the use of an SCBA or positive-pressure supplied-air respirator with escape SCBA (used to safely exit environments that contain toxic substances or where oxygen deficiency may occur) and hooded chemical-resistant clothing. Options for the latter include overalls and a long-sleeved jacket; coveralls; a one-or two-piece chemical splash suit; and disposable chemical-resistant coveralls.
Level C provides liquid protection and allows workers to use respiratory gear other than an SCBA, while Level D — usually a basic uniform or coverall that offers protection against simple hazards — represents the lowest form of protection and is not appropriate for chemical hazards.
IN THE KNOW
The appropriate selection of apparel requires knowledge of chemicals that a worker might come into contact with on the job. And it is not just about the gear; knowing how to use that equipment is important too. Riesberry, who thinks that getting a feel for hazmat suits beforehand is imperative, recommends workers to use training suits ahead of time so they know what to expect.
“[Employers] don’t want them to go into that environment for the first time and realize how they are going to react at different points,” Riesberry says. “You are going to have regular heat stress and then your adrenalin is going to start pumping up as well.”
Dr. Zeigler says the National Fire Protection Association (NFPA) document, NFPA 1991: Standard on Vapor-Protective Ensembles for Hazardous Materials Emergencies, “pretty much [sets] the fundamental design criteria for all the Level A suits in North America.”
He describes Level A gear as “basically an all-hazard suit” that — depending on design features such as protected enclosures and exhaust valves — can guard against vapour, liquid and particle hazards. Despite their protective might, Level A suits do present a concern when it comes to the possibility of heat stress. “Hazmat Level A suits are notorious for this,” Dr. Zeigler adds.
Peter Kirk, product manager for Saint-Gobain Performance Plastics in Merrimack, New Hampshire, agrees, calling comfort “a relative term.” A worker wearing a fully encapsulating hazmat suit is going to be uncomfortable, “because you are trapped inside of the suit, exhausting your hot air into it.”
Several factors can contribute to increased heat, Kirk says, including the weight of the encapsulated suit (usually about three to nine kilograms), its flexibility (which can help enhance user manoeuvrability) and its overall fit. Kirk recommends looking at standards, rather than industry classifications, for guidance. “There is a lot of differences in performance,” he says.
Dr. Zeigler reports that members of the United States military wear absorbent carbon suits that are porous and allow air to flow in and out. Tested against chemicals that military personnel may encounter, he says the hope was that a membrane (fibres or fabric that provides protection against chemicals) could be developed that would offer industrial workplaces the breathability of the military option. “The membrane technology is still struggling along,” Dr. Zeigler says. At present, though, it does not seem to be “translating to a significant impact” for the industrial market.
Andrew Wirts, sales and marketing director for NASCO Industries Inc. in Washington, Indiana, agrees that it can be a challenge to identify a membrane that will resist the penetration of a molecule of chemical, yet allow a perspiration molecule to evaporate through it.
Dr. Zeigler cautions users to ensure that garments worn under thermal protection will not melt. As for gear worn over top, a regular chemical protective suit should not be worn over flame-resistant (FR) clothing “because you won’t get any FR protection,” he adds.
Jason Contant was the former editor of Canadian Occupational Health and Safety News.