Hot and Bothered
By Jason Contant
Some emergency responders in Florida helping to clean up the massive oil spill in the Gulf of Mexico are taking a different approach to summer's oppressive heat while toiling in necessary protective g...
Some emergency responders in Florida helping to clean up the massive oil spill in the Gulf of Mexico are taking a different approach to summer’s oppressive heat while toiling in necessary protective gear: working at night.
“It gets them out of the sun and off the hot sand,” James Zeigler, Ph. D., research associate for DuPont Protection Technologies in Richmond, Virginia, says of responders to the largest oil spill ever to hit the United States.
Working at night has become necessary to address the havoc wreaked by millions of gallons of oil unleashed after a fire aboard the Deepwater Horizon drilling rig in April. But that approach may not be feasible or desirable in other circumstances.
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, national sales manager for Lakeland Protective Wear Inc. in Brantford, Ontario. Consideration of the work process is also critical.
Second, Riesberry notes that a coverall and apron may suffice for lab work. But change that task to tank cleaning, where workers may be “surrounded in the chemical or it is coming at them from all angles,” and a higher degree of protection will certainly be needed, he says.
A third key consideration is how long a worker will remain in the hazardous environment, says Riesberry. Some chemicals may permeate a protective fabric in 30 minutes, meaning a worker will have enough time “if you’re just going in to release a valve or to do some maintenance around a pipe,” he says.
But that half-hour of protection will hardly suffice if the task is cleaning up a larger spill, Riesberry adds.
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. Zeigler. “People have a chemical hazard and they get tunnel vision around the rest of the hazards that are present,” he points out.
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, adds Dr. Zeigler.
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 Lakeland Industries. It involves encapsulation in a vapourtight chemical suit and the use of a self-contained breathing apparatus (SCBA) or supplied-air system.
That 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, he notes 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, Lakeland Industries reports.
This type of gear typically does not provide protection from vapours, but does require use of an SCBA or positive-pressure supplied-air respirator with escape SCBA (used to be able 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.
Then there are the last industry classifications of hazmat gear: Level C provides liquid protection and allows workers to use respiratory gear other than an SCBA; and 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
Appropriate selection of apparel would be tricky if chemicals on the job are not known. However, workers at the Clean Harbors Environmental Services facility near Sarnia, Ontario “almost always know” the hazards on site, reports Doug Smith, regional health and safety manager for the Norwell, Massachusetts-based company.
Work at the site, which has a landfill and hazardous waste incinerator, involves offloading, sampling and treating hazardous waste, Smith says. And that makes use of Level B garments the best and safest bet.
“What happens in our case is before we receive the material, we get a sample and then we develop a profile of that material or a waste data sheet,” he says. “So depending on what that material is and what concentrations the chemicals can be, we assign PPE (personal protective equipment) to it, which could be a glove, suit, respirator,” Smith says.
But it’s not just about the gear; it’s about knowing how to use that equipment. Riesberry suggests that getting a feel for hazmat suits beforehand is imperative. He recommends that workers 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’re going to have regular heat stress and then your adrenalin is going to start pumping up as well.”
Those in the market for chemical-resistant clothing can get some guidance from certification standards in the United States, since Canada does not have its own. South of the border, there is the National Fire Protection Association (NFPA) document, “NFPA 1991: Standard on Vapor-Protective Ensembles for Hazardous Materials Emergencies.” Dr. Zeigler says it “pretty much [sets] the fundamental design criteria for all the Level A suits in North America.”
NFPA 1991, 1992 and 1994 detail actual certification requirements for flame resistance, chemical testing, physical properties and chemical preconditioning, says Peter Kirk, product manager for Saint-Gobain Performance Plastics in Merrimack, New Hampshire. Kirk’s recommendation is to look to standards, rather than industry classifications, for guidance. “There’s a lot of differences in performance.”
Dr. Zeigler describes Level A gear as “basically an all-hazard suit,” one that — depending on design features such as protected enclosures and exhaust valves — can guard against vapour, liquid and particle hazards.
Kirk says that the “mainstream” valve in the market has a butyl diaphragm, which can be negatively affected by exposure to the elements. The diaphragm requires routine maintenance and typically needs to be replaced every two years.
Kirk’s company offers a silicone diaphragm as an alternative. “Silicone is very resilient and inert, so it doesn’t change properties from exposure to heat, cold and the environment, whereas butyl rubber [can] dry out,” he reports.
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,” says Dr. Zeigler.
Kirk agrees, calling comfort “a relative term.” A worker wearing a fully encapsulating hazmat suit is going to be uncomfortable “undoubtedly, because you are trapped inside of the suit, exhausting your hot air into it,” he says.
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.
Of the heat build-up, Dr. Zeigler says that “the good news is it’s manageable; the bad news is there’s no magic bullet.”
BREATHE IN, BREATHE OUT
Zeigler reports that members of the U.S. military wear absorbent carbon suits that are porous, thereby allowing air to flow in and out. Tested against chemicals 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 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 says “there is still the buzz around breathable fabrics and [whether] they really work.” Do they have some positive effect, and if so, how much? he asks.
Then there is the effect of layering protective gear. Take, as an example, equipment for structural firefighting. It consists of an inner liner, a moisture barrier and an outer shell, the last feature providing insulation, cut resistance and integrity, notes Dr. Zeigler. “So if you are in a flash fire, the outer shell holds up for a long time before it gets used up,” he says.
“Those suits are built to reduce burn injuries and enhance survivability,” he says, emphasizing that the gear may reduce, but cannot completely eliminate, injuries. The garments have delicate membranes, though, meaning they can be compromised in a flash fire or thermal event, says Dr. Zeigler.
The moisture barrier offers some moisture transport out of the garment, prevents moisture from coming inside the suit and may serve as a bit of a barrier to chemicals. If the chemical exposure is heavy, however, a “fundamental decision” must be made as to whether the overriding need is to guard against fire hazards or chemical exposures, Dr. Zeigler advises.
So what about workplaces such as refineries, where both chemical and fire hazards are present? Wirts reports that suits are starting to hit the market that feature both chemical splash and flash fire protection. “It’s not that common, but at least now it’s available,” he says.
Up until 2007, Kirk says, there was no flash fire NFPA 1991-certified garment for this “small segment of the market. The option for that flash fire configuration had existed for many years in the standard, but nobody had ever met that.”
In fact, when Saint-Gobain surveyed fire departments across the United States about their need for flash fire protection and their willingness to pay more for that option, “the quick answers were always ‘no,'” Kirk reports.
But once the company introduced products to meet those twin needs, “the majority of our sales became our newly introduced flash fire product,” he says. Sales show “a very strong preference” for items with optional flash fire protection.
UNDER AND OVER
Dr. Zeigler says users must ensure garments worn under thermal protection will not melt. As for gear worn over top, in general, a regular chemical protective suit should not be worn over flame-resistant (FR) clothing “because you won’t get any FR protection,” he says.
NFPA 1991, which outlines requirements for single-and dual-skin configurations, allows two layers of protective apparel to be worn, Kirk says. The problem has been “the misconception that the overcover was for flash fire, but that was not true,” he says. “I cringe every time I hear it.”
While the overcover may offer some shielding from flash fires, “it is not providing enough protection” to meet the NFPA 1991 performance requirements, Kirk says.
The next version of the NFPA 1991 standard is slated for a 2011 or 2012 release, Kirk says. “There have been proposals put together to eliminate the allowance of that dual layer.”
When the standard was first developed in the 1980s, “the technology was with materials that burned or couldn’t resist exposure to abrasion and provide the high-level chemical protection.” As a result, there was a provision for an “outer skin” or second layer to help provide protection.
But Kirk contends that industry has moved away from the dual-layer configuration, saying that the approach of the commission updating the NFPA standard is to “let the market decide” if single-skin configurations are preferred.
Kirk recalls the survey of fire departments that operated without flash fire protection, but still felt they were working safely. “The perception was, ‘We never had it before. Why would we need it tomorrow?'” he says. “Who wants to think, ‘Maybe I have not been safe in the past few years?'”
Jason Contant is editor of CANADIAN OCCUPATIONAL HEALTH & SAFETY NEWS.