Everything you need to know about heat and flame protection

Top industry experts weigh in on what to look out for in heat and flame PPE

Everything you need to know about heat and flame protection
Heat and flame PPE is key for a number of Canadian industries

Editorial note: This feature will not cover PPE for firefighters as that is a very specific niche and deserves its own editorial (keep your eyes peeled in future for that!).

Each year, hundreds of workers in Canada are affected by heat stress. According to the United Food and Commercial Workers Union (UFCW Canada), an estimated 220 workers in Canada and the U.S. die each year from occupational heat stress.

Heat stress — and heat-related injuries such as cramps, syncope or hyperpyrexia — occur when the body overheats. The Canadian Centre for Occupational Health and Safety (CCOHS) says that most people feel comfortable when the air temperature is between 20°C and 27°C (and when relative humidity ranges from 35 to 60 per cent).

Danger occurs when very hot environments drive your internal body temperature several degrees above the normal temperature of 37°C, which overwhelms the body’s natural cooling systems.

There are many factors that can contribute to heat stress: air temperature, hot sources, humidity and, of course, what type of clothing or equipment a worker is wearing. There are several things employers can do to ensure that workers are safely working in hot conditions — wearing the right PPE is a key part of this.

Heat protection is, of course, necessary in certain environments that are typically hot. But what is interesting is that 17 per cent of all exertional heat injuries happen in the cool weather or in the shifting of the seasons, says Heidi Lehmann, chief commercial officer at Kenzen.

Other drivers of heat injury — regardless of whether the environment is hot — are things such as poor hydration, high exertion or poor acclimatization. Lehmann says this is a problem for new workers, for example, who are not used to a site or a particular type of work.

Another factor to consider is microclimate. “Microclimate is the temperature between the skin and the clothing that you are wearing,” says Lehmann. This difference in temperature within the same body is something to keep in mind, notably for workers who need to wear layers.

Specificities of the employer’s duties may vary from province to province, but, usually, some kind of adequate PPE is required. UFCW Canada says Canada does not have specific laws or regulations that govern heat exposure and heat stress. It says that the government, usually under the office of the Ministry of Labour, applies threshold limit values (TLV) as outlined by the American Conference of Governmental Industrial Hygienists (ACGIH).

Regardless of legislation, employers need to ensure that they are investing in proper PPE to ensure worker safety.

Heat protection

It can be confusing for consumers to know which materials to look out for — especially because each industry has different needs and the dangers of exposure to heat can manifest in different ways.

“The ability for a fabric to lock heat or to prevent the transfer of heat through is what you should be looking at,” says Brian Nutt, product director at Tingley. “As a consumer, you want to be concerned about what the potential level of heat that could hit the garment is and how much of it is going to get blocked and trapped or get transferred through to the wearer.

“[Tingley does] a lot of liquid-proof apparel. People are concerned about liquids melting the [high heat-resistant] suit and passing through which is what complicates a situation,” says Nutt.

He notably mentions steel workers working with materials such as molten steel.

Indeed, this is an environment that is very much concerned by heat protection: Steel mills that are processing molten metals or refineries where there is high heat around may have workers that are worried by not only the liquid heat but also the steam that comes out of the lines.

There are several other industries where workers are exposed to heat stress and other such dangers. These include agricultural or forestry settings, where seasonal workers or others are working outside in the summer. Indoor workers are also at risk. This includes the aforementioned steel mill workers but also welders and metal fabricators and those who work in foundries or bakeries, for example.

Workers should wear breathable, lightweight fabrics that are comfortable and light-coloured (to avoid absorbing heat).

Workers may want to look into wicking fabrics, which pull moisture away from the body and push it toward the surface of the fabric where it can evaporate. Many wicking fabrics are made of high-tech polyester. Another material commonly used for heat-protective workwear is polyvinyl acetate (PVA). Not so much heat resistant as it is cooling, it is ultra absorbent and can hold water for a long time.

There is also protective clothing such as vests that use water or ice packs integrated into the garment to keep the user cool for a number of hours.

Smart PPE

Protective clothing is important, but tech advances are also pushing the boundaries of health and safety onsite. Wearable tech in particular can be an interesting solution for employers looking to track heat exposure — and there is a growing demand for these smart devices.

“[Kenzen is] focused primarily on heat, but when we started the company, for most industrial companies that we talked to, this was a growing problem that was happening on the worksite,” says Lehmann.

“[Smart PPE] is definitely a trend that is growing and a lot of it is because safety is now encompassing sensors and technology in a way it never did before,” she says.

Kenzen manufactures smart PPE that helps monitor workers for signs of heat stress. These wearable devices monitor physiological indicators (core body temperature, heart rate, etc.) to give the worker and their supervisor an accurate view of the impact of heat on the worker’s body.

If a worker is at risk, the worker’s device will vibrate and suggest that the worker stop, seek shade, hydrate, etc. Lehmann says it is also essential that the device is waterproof, due to sweat and hot temperatures.

She says these products are most commonly asked for in industries such as construction, mining, renewable energy, utility and field services, as well as mining, although an intrinsic safety (electrical) certification is essential for a device to operate within coal mines, as well as the oil and gas industry.  The Kenzen device is currently designed for intrinsic safety with the certification to follow over the next several months.

Heat exposure, as mentioned before, is a significant and growing threat. For example, she says there has been an increase of almost 60 per cent of heatstroke and exhaustion cases in the U.S. military since 2008. But heat also impacts productivity, says Lehmann: There is a 26-per-cent loss in productivity when workers labour in 35C heat.

Fire resistant vs. fire retardant

Fire protection can be a bit more confusing. “People get very confused between what is fire resistant and fire retardant,” says Simon Levin, Canadian sales manager at True North/Dragonwear.

Fire retardant is a term that denotes that something extinguishes fire or prevents the fire from spreading. A hand-held fire extinguisher is a good example as it contains chemicals that, when applied to a fire that is in progress, the chemicals hold back the fire and if the conditions are ideal, the chemicals will completely extinguish or “put out” the source of the fire. “Retardant” means to delay or hold back in terms of progress.   

All garments used that are FR certified are flame resistant. This means that the garments “resist” being ignited in the presence of direct contact from flames. The mechanism that makes a garment resist flames is because the garment contains flame-retardant properties. That is, all the way down at the yarn and fibre level, the garment contains flame-retardant chemistry that allows the garment to resist flames and thus resist ignition. Garment ignition a primary driver of personal injury, not the source fire to which the end user has come in contact or is in close proximity.

There are two primary types of flame-resistant garments in the market. Those that have been manufactured with fabrics that have been chemically treated with flame-retardant chemistry are referred to as “treated FR garments” and those that have been manufactured with flame-resistant fibres, yarns and fabric are FR without needing a subsequent garment treatment with flame-retardant chemistry. These garments are referred to as “inherently flame resistant.” Flame resistance is a natural property of the garment itself and not the result of chemical post-treatment of the fabric used to make the garment.

What does inherent mean? It means that the flame resistance of the garment is a permanent part of the garment as it is designed in at the fibre and yarn level, so it will never wash out and will be FR for the life of the garment,” says Levin. Inherent garments would only really have to be replaced if they get a hole in them or if a seam rips, for example.

“It is incumbent upon the wearer to assess the condition of the product. And as soon as the product starts to look worn, they are going to have to assume that it is decreasing the level of protection that the product is providing,” says Nutt.

Arc and flash fire

Flame resistant is a very overarching term that is used for a number of different levels of protection, says Nutt. And because this is such a broad term, users may encounter protective clothing and equipment that is “flame resistant” but which has dramatically different levels of performance.

“It has the potential to really hurt or injure the wearer,” says Nutt.

The way that the market is starting to move, he says, is that people are slowly moving toward using the terms “arc resistant” and “flash fire resistant” for flash fire hazards, which are more common in the petrochemical market or in gas utilities (see boxout).

Base layers

Wearing over garments like fire-retardant coveralls is essential, but what the worker is wearing against their skin is also very important. Aside from whether a garment is inherent or chemically treated, there is also much to be made about how a garment performs, such as how it moves and wicks moisture and how fast it dries.

As with heat protection, moisture-wicking garments are a big part of flame protection. However, users need to keep in mind that certain materials fare better than others.

Levin points out that so many people wear cotton, but cotton is one of the most absorbent fibres that you can get. It can hold twice its weight in moisture, which can get uncomfortable for the wearer.

Furthermore, if a garment is impacted by a source of fire or arc or flash, if it is soaked in moisture (like a cotton garment would potentially be), that moisture is next to skin and hasn’t been moved away from the skin by a more technical garment. As a consequence, if a worker is in an arc or a flash, this moisture could potentially boil and give the user steam burns.

“Dragonwear is all about base layer,” says Levin. This includes wicking and moisture transfer. “My whole goal and intention in the world is for safety people to understand how important it is what you wear next to your skin.”

What to look for

There are a number of industries that are concerned by FR protective clothing, such as utility workers, pipeline workers, welders, miners, people in manufacturing facilities that deal with electrical, workers in chemical plants making fertilizers, etc.

“Anywhere where there is even the slightest danger of combustibility, you should be wearing safety clothing, and most of them are mandated by standards,” says Levin.

“What renders a garment that you can trust is the amount of testing and the stipulations of the standards that it's met,” says Levin. “You should always be looking at the label inside of a garment; the label will tell you whether it's met certain standards and has been tested to meet those standards.

“I would always look for a garment that is inherent as opposed to a garment that's chemically treated. There are numerous documented cases talking about the percentage of the workforce that has experienced skin rashes and allergic reactions to the chemical that's next to your skin,” says Levin.

From a cost perspective also, an inherent garment may cost considerably more initially, but in the long run will be more financially sane.

Generally, says Nutt, if you are looking for liquid proof performance that is also flame resistant, two common materials are polyurethane FR and PVC.

“They both have pros and cons,” says Nutt. “In Canada, the polyurethane is a little bit lighter weight and generally holds up better in the extreme cold. And the PVC is generally a little bit more cost effective. But it also has more chemical resistance or a wider range of chemical resistance.”