In 2008, a research assistant working in a chemistry lab at the University of California, Los Angeles was transferring a liquid chemical from its original bottle to another bottle. The chemical involved, tert-Butyllithium (or t-BuLi) is highly pyrophoric: it ignites on contact with air. She had put on goggles and gloves but, instead of a fire-resistant lab coat, was just wearing a synthetic-fibre sweatshirt. For the transfer, she had to insert the needle of a large plastic syringe into the bottle’s seal to draw the liquid up. As she did so, the syringe came apart in her hands. The spilled liquid instantly ignited and set her sweatshirt on fire.
Sheri Sangji, who was 23 years old, suffered second- and third-degree burns to almost half her body and died 18 days after the incident.
Many workers require protection against both fire and chemical hazards. These hazards are present with many of the tasks performed in workplaces such as refineries, petrochemical plants and laboratories. It has always been difficult to provide effective protection for workers who face these dual hazards because of the limitations of garment materials. Today, however, some newer fabrics coming onto the market combine increased chemical protection with fire resistance.
Flame resistant and chemical protection (FR/CP) garments can be divided into three levels and types of clothing, says Paul Bryce, vice-president and general manager of the chemical solutions strategic business unit at Cowansville, Que.-based Ansell Canada. In heavy industrial workplaces or fire and emergency services, there are re-usable materials that have added materials, such as Nomex, embedded into them.
“If a firefighter is responding to a chemical spill and there happens to be a flashover (the ignition of exposed combustible material in an enclosed area), then these suits are tested to an extent that the flashover will not cause the suit to fail. In other words, the firefighter still has enough protection from the suit to get out of that environment and save their life,” he says. “That’s the pinnacle of protection from a chemical. These suits are designed to protect against pretty much anything. And at that level of protection, they are also designed to deal with a flash-fire instance.”
The next level down is the liquid-protective suit, Bryce says. This also is a re-usable, chemical protective garment that a worker wears over top of a thermal protective garment to provide splash-chemical protection.
Finally, there are disposable suits. These are designed primarily to protect against a chemical, whether that is liquid or dust. Most of the disposable or limited-use garments on the market are essentially sacrificial, he says. They’re meant to limit the spread of a fire.
“In the event of a flashover incident, when the flame is removed, the garments are designed not to continue to burn, not to melt and not to drip and cause secondary issues. Indeed, it’s the layering system, the wearing of a Nomex or Proban, or another type of flame-retardant clothing underneath that protects the person. These outer chemical suits are just designed not to add fuel to the fire, so to speak,” Bryce says.
When workers in refineries and petrochemical plants require protection against harmful chemicals, the usual practice has been to wear a chemical suit over a thermal protective garment. The thermal protective coverall is often made of Nomex (or other aramid) or a flame-retardant cotton and acts as a guard against flame, heat and flash fire.
However, chemical suits are generally made from a blend of polymers, usually polypropylene and polyethylene, which are thermoplastics and flammable. Coming in contact with a flame or flash fire, the chemical suit will not only burn but also melt and drip burning plastic that will stick to clothing and skin. Wearing a chemical suit made of thermoplastic material greatly reduces the protective quality of the thermal protective garment underneath.
As a result, safety managers have often had to decide which hazard was a bigger concern: potential for flash fire or exposure to a dangerous chemical, says Randy Hillmer, Calgary-based national sales manager for Canada at Lakeland Industries. Very often, the person had to choose chemical protection without the fire retardant because it was the most likely hazard.
“The PPE choices did not match up with the requirements of the workers,” he says.
But in recent years, while protection from flash fires hasn’t really changed much, the technology for chemical protection has advanced significantly, Hillmer adds. For example, 20 years ago, Lakeland sold a garment that was designed to protect against very light chemical splash. Fifteen years ago, it came out with a garment that was for light splash protection from a fairly wide range of chemicals. Its newest garment provides a “fairly high level of chemical protection, while it maintains fire resistance,” says Hillmer. It is designed to be work over an FR garment.
“Now, technology has moved along in this, and there has been a huge improvement in garments that offer the chemical protection that people need but still maintain all the features and benefits of their thermally protective garments,” he says.
Another kind of FR/CP product is called a “single skin,” designed to be worn alone, says Hillmer. The garment is made by directly laminating a thermally protective fabric with a chemical barrier film.
“If I’m working in an environment where I have to wear a Nomex coverall, I go in during the day, I put on my Nomex coverall and I start my work day. Now — and this is another reason I like the two-garment system — if I have a job that requires chemical protection, as well as my FR protection, I just get my Pyrolon garment, I pull it on over top and I go back and do my job,” he says.
“If I decide I want to go to single skin, I go and I take off my Nomex coverall and pull on this other expensive garment and I go do my work. And when I’m finished, I take that expensive garment off and put my Nomex garment back on.”
Hillmer believes the dual protective FR/CP garment is preferable, from both a safety and cost perspective, to the single skin garment.
“The best friend somebody has when they are in a flash fire is insulation from air. When you layer a garment, you get better protection because there’s a layer of air trapped in between each of the layers. When you have single skin, you don’t get as good a flame protection as you do with layering garments.”
DuPont has also recently introduced a new FR/CP safety suit designed to provide an effective barrier against a wide range of chemicals, including many inorganic acids and bases and industrial cleaning chemicals. At the same time, the coveralls, which are designed to be worn in refineries, petrochemical plants, laboratories and some hazardous maintenance operations, can maintain secondary flame resistance. In the event of a flash fire, the coveralls do not ignite and so act to prevent the spread of burn injury when worn over standard FR garments.
In laboratories, workers generally wear one of two things to protect themselves: a plain poly-cotton lab coat or a two-piece system where a secondary item, such as a rubberized apron or disposable lab coat, is put on over a flame-resistant lab coat.
One of the main problems with the two-layer system is that workers are often reluctant to wear the secondary protective piece, says Mark Saner, technical services manager at Oxnard, Calif.-based Workrite Uniform Company. Workers who have performed a certain kind of experiment for many years tend to think they don’t need to go to the trouble of getting and putting on the extra layer.
“That’s when accidents happen and they wish they had put it on,” Saner says.
On other occasions, workers may be so focused on their work that they simply forget to put on the chemical apron or they just don’t want to wear it because it’s inconvenient or uncomfortable. Moreover, as with the chemical suits worn by industrial workers, the second layer — such as a disposable chemical-resistant coat — may not be flame resistant.
“So, if there’s a flash of some sort and it ignites, even though you’re wearing a flame-resistant garment underneath, you’re still going to get burned because that outer garment is on fire. The outermost layer in a flammable situation always has to be the flame-resistant layer,” he says.
A relatively new material being used to manufacture lab coats is designed to provide protection against both the chemical and fire hazards that lab workers are often exposed to, Saner says. The base fabric of the Workrite FR/CP lab coat is a Nomex blend. A treatment applied to the fabric gives it its ability to repel many common acids and corrosives used in labs.
“The key to it is, it’s not like a barrier suit; it’s not impermeable totally. It’s for that inadvertent, accidental-type splash situation. You don’t want to splash some acid or a corrosive substance onto your skin,” he says. “This lab coat gives you a little better protection than just having on a plain lab coat or plain woven garment that would not give any resistance to repelling any of those liquid chemicals.”
Investigators looking into the chemical fire that killed Sangji concluded there had been systemic safety failures at the laboratory. The lab had been cited for safety problems in the past and there were earlier incidents in which two students had been seriously burned. They also found Sangji had not been trained properly and had not been issued a lab coat. The chemistry professor who had hired her was charged with four felony labour code violations. The case led to the first criminal prosecution of an American academic for a lab accident.
Almost six years after Sangji’s death, the case ended in a settlement that allowed the professor to avoid a guilty plea and criminal penalties. Her sister, who called the settlement “barely a slap on the wrist for the responsible individual,” also told the court on the last day of the trial: “We can only hope that other young individuals are better protected in the future.”
Linda Johnson is a freelance journalist based in Toronto who has been writing for COS for seven years.
This article originally appeared in the June/July 2018 issue of COS.
What are the consequences of precarious employment?
Studies have shown that there are many negative consequences attributable to precarious employment and, specifically, temporary work. Workers experiencing precarious employment:
• are more often exposed to hazardous work environments, stressful psychosocial working conditions, increased workload, including unpaid overtime
• suffer a higher rate of occupational safety and health injuries
• experience ill health effects
• experience increased work-life conflict
• are less likely to receive adequate training for the tasks they are required to perform
• are less likely to be members of trade unions
• have less protection due to limitations, loopholes and exclusive interpretations of legislation.
Source: Canadian Centre for Occupational Health and Safety