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Managing heat stress in the workplace

Safe Work Month 2019

Dr Matt Brearley

Presented by: Dr Matt Brearley

Dr Matt Brearley is Australia’s pre-eminent occupational heat stress consultant. He’ll highlight the consequences of heat, the seasonal patterns of harm and the pseudoscience that exists within contemporary heat stress management. Proven strategies to maximise worker health, safety and productivity will be discussed. The prevailing hydration and cooling practices will be challenged by the application of research findings, with case studies from some of the harshest environments on earth.

Run time: 17:46

Download a copy of this podcast (MP3, 16 MB)

Managing heat stress in the workplace

Presented by: Dr Matt Brearley

[Start of transcript]

Spencer Howsen: Matt Brearley, welcome to the podcast.

Dr Matt Brearley: Thank you.

Spencer Howsen: Let's start off with a very broad, big question. What is heat stress? And then we'll get onto the impact on workers, and what employers can do about it.

Dr Matt Brearley: There's lots of definitions, but there's only one, really. It's the net load of the work and the climate, on your body. So, think of the heat being produced within you, the heat and humidity that is outside of you, and it's a combination of those two factors. That is what heat stress actually is.

Spencer Howsen: And give us an idea of the sort of places where heat stress presents itself, cause it's not in most people's lives, I would think as long as the air conditioning's working correctly.

Dr Matt Brearley: Yes, when we have the opportunity to choose where we can be. But obviously, lots of workers are exposed through seasonal patterns of exposure. So, we're not out there in it all the time, although some workers are. Deep underground mines that really don't fluctuate in temperature or humidity, they're hot all the time. They're constantly exposed. But in most workplaces, it's a seasonal issue. So, as we come into summer, the weather starts to ramp up, we start thinking, "Oh, this is a bit uncomfortable, a bit warm in these conditions. Might have to slow down my work rate, no we've got to get the job done." I start producing and storing a lot of that heat, because now it's warm outside, that heat that used to leave my body in winter, now it's very hard for it to leave the body, because the air's already hot.

Dr Matt Brearley: We might actually be absorbing heat through the air. That's okay, we can sweat. And so, the evaporation of sweat will fix that, but now it's humid. Oh, not evaporating as much, either. So now, where's that heat go? It stays inside my body, and causing my temperature to rise. So, I'm got a bit of an issue now, because the boss wants that job done, I'm a bit warm, really wasn't expecting it to be this hot today, so I don't have a lot of resources at my disposal, and bang, I'm in heat stress. So, that's how it typically presents in the workplace.

Spencer Howsen: So, the amount of work that can be realistically and healthily achieved will differ from place to place around Australia, and also, depending on the time of year.

Dr Matt Brearley: 100 per cent. Being a nerd, and a heat nerd specifically, we'd call that workability. The ability to get the work done, the percentage of the work day you can spend doing the work rate you need to, to get the job done, comes down as you head further north. And that's due to heat and humidity. But having said that, we have heat waves, we have heat waves right across Australia. So, at any given time, that work ability can be impacted. So yes, we have, I tell you, some examples of where it gets really awkward, in terms of heat stress, is where a crew quote for work, they basically produce a schedule of work based upon what they think the conditions will be. The conditions are worse than they expected, and the ability for those workers to deliver that product is compromised. So, you either deliver it and pay for it, in terms of some serious heat stress within the crews, or you add workers to share that heat load. And obviously, that's the message that we're putting forward, that heat should be shared. But, there's not always a commercial agreement around that.

Spencer Howsen: Okay, what's so bad about heat? What does it do to people?

Dr Matt Brearley: Look, our bodies are designed to be able to handle a rising core body temperature and skin temperature. We're not always going to be at a set level where we're not sweating. So, it's not a huge deal when you look at by itself. But obviously, it's consistent and sustained, so there's still issues when it gets very high, in terms of core body temperature, very, very dangerous. Our cells do not like that. If you have a core temperature up in the 39s, heading towards 40, you can expect that some cells will start leaking. Our bodily cells really do not like high body temperatures, and especially, the membrane around those cells, it is quite heat sensitive. So, it starts to leak. These cells leak, and we have cell death. And, if you have enough cell death, you will have a permanent issue.

Dr Matt Brearley: And that's why some people will know of or have heard of workers who have permanent brain impairment, due to a heat stress/heat stroke event. If it's sustained, so, long enough, and if it's high enough then that cell death can result in multi-organ failure. So, the actual organs fail, and that's where workers don't get to go home. And we'll have a workplace fatality due to heat. In those cases, it's extremely sad, and highly preventable.

Spencer Howsen: And yeah, and very serious, clearly. So, now we've got everyone's attention if we didn't already. So, you use the word preventable. Sharing the heat, you've already given us that tip. Give us some other ways that heat stress can be reduced.

Dr Matt Brearley: So, preventing it is great and like I said, sharing the workload. But, there's lots of places and cases where that may not be possible. So, how do we manage that? Well, it's all about keeping the core body temperature low. So, if you can keep the core body temperature low, and get the job done, we're all good. That's, that's the goal. So, how do you do that?

Dr Matt Brearley: Well, first of all, we may need to drop our core body temperature before we start work. Now this will be against everything our brain has learnt. We cool down once we get hot, not before. But there's a couple of little tips and tricks that we can use. So, some workers will go into a hideously hot environment, they may be putting on some Tyvek suits, or there might be firefighters putting on turnout gear. They're going into fires, and they just know, they know it's going to be hot in there, but the job has to be done. It's not like a firefighter can say, we'll wait till that cools down, and we'll go and see if there's anyone in there. They're going in to rescue you. If they drop their core body temperature, it opens up their window before they hit the heat stress, before they go into a heat stroke. It just lessens their likelihood of suffering harm.

Dr Matt Brearley: And, that might be through the use of a slushie drink, an ice drinker, I guess, a Slurpee, I'm not sure of all the terms used, but I think that describes it. So, ingesting ice is a potent in reducing your core body temperature. Basically, your body will melt that ice. It requires a phenomenal amount of heat to melt it. That heat comes from your body. That's just, that's the heat that couldn't get out to the environment, because it's too hot, it's too humid. So, you've helped put that fire out, and you've dropped your core body temperature, and now you're very cool, and you're able to go in and get the job done. Your sweat rate might be a bit lower if you're in a hot, dry climate, because of that. But definitely, in hot, wet, tropical climates, slushie ingestion pre-work is a great tool to drop their core body temperature.

Spencer Howsen: But how, if you're a firefighter, let's just keep with that example, you've got to, how long is that benefit going to last for, before you need another slushie? And, next thing, you're high on sugar.

Dr Matt Brearley: Yeah, sure. So, first of all, we go the no-sugar options. And, I'm a big fan of just the ice, myself. But obviously, we know that large, a large bowl of ice can be quite unpalatable. So, you can make it with cubes of watermelon, frozen watermelon. If you want a little bit of flavour, you can add a little bit of cordial, do whatever you need to do. But, low-sugar is best. It depends on the volume, in terms of how long that will last. Depends on the size of the worker, and how hard they working.

Dr Matt Brearley: But we've seen firefighters depress their core body temperature over a 20 and 30 minute window. So, they're only going to do 20 minutes to 30 minutes straight, because that's how long their cylinder will last on their back, while they're doing the fully self-contained breathing apparatus work. So, for the majority of that 20 or 30 minutes of exposure, their core body temperature is much, much lower than it would have been. That is of great benefit to them. They're able to make better decisions, stay cooler, and importantly, get back in there. So, they'll drop that cylinder, hopefully have a quick cool-down, and go again. Whereas. Those that don't get the cooling, are the ones who will tend to cook. They'll work a slower rate, and they may not be able to respond.

Spencer Howsen: What are some other things that... you must have a whole... I'm imagining you've got a whole bunch of tricks in your tool bag.

Dr Matt Brearley: Well look, we definitely need a pretty diverse toolkit, because slushies is not the answer. Slushies is the answer for some workers. We have workforces that do a heat stress survey, and they're reporting, across northern Australia, that 35 per cent of them use slushies on a daily or weekly basis, but they're 65 per cent that aren't.

Dr Matt Brearley: Look, airflow is important. We know that. So, airflow can help lessen that core temperature curve, it can take the edge off it. Using fans in the workplace can be a good idea. For some workplaces, it's dusty, and that's not appropriate, but now I've got the point where we have tools that use batteries. So, do you think of drills and grinders, et cetera. Those same batteries can now power fans. So, where some workers would say, no, I'm in the middle of nowhere, I do not have access to power. Not mains power. And, so a fan's are useless to me. I've got absolutely no use. But now, they're able to use the same batteries that their tools run off. A small and relatively inexpensive fan, and it can provide some sustained cooling power. So, that can take the edge off.

Dr Matt Brearley: A lot of workers will talk about, "What about ice vests? And neck coolers, and collars?" And stuff like that. And, we look for sustained cooling power, and unfortunately, it seems like the vests worn while doing work. Yes, once your core temperature rise. But, cooling down after work, or in between work bouts, they're not that effective. And, one big issue been, where and how do these workers recharge them? So, once they've got warm, we can't put them in a esky full of ice. Definitely can't do it with other workers, cause now you're sharing bodily fluids, et cetera. It becomes a bit of a logistic issue. So, we don't see those types of methods being used very readily.

Dr Matt Brearley: What we do see, is that workers are now, on some sites, using small eskies as their own personal cooling container, or bucket, if you want, and they're able to dip towels, their own towel, in this slurry of ice and water, and drape over them. They might have moved to a PPE-free area to have their lunch, they might be in air con, which we know is a great method. I'm assuming a lot of workers have access to air con. We see that does make a big, big difference, but if you don't, then access to a cooling towel dipped in an ice slurry, draped over your exposed skin in a PPE-free area, is a very, very solid method. Mixed with air flow, even better.

Spencer Howsen: So, what do employers and organisations need to do, to stay on top of the latest thinking, and to make it a part of the culture of their organisation, to think about heat?

Dr Matt Brearley: Yeah. We leave it to the workers. We see workers based in hot regions, and those seasonally exposed to heat. Yes, they have some resilience, but they're not generally going to put their hand up, to say that I'm suffering. So, we think they're resilient, but the survey's showing these symptoms are very, very frequent. And, when asked and answered anonymously, they're coming through. But, in the workplace, they're not being reported.

Dr Matt Brearley: So, we want workplaces to have a culture where it's okay. It's okay to put your hand up. And, we know across northern Australia, everyone's suffering heat. It's hard to live, let alone work up there. We all know that. And, deep down we will admit it, in an anonymous fashion. So, we need workplaces and we've seen a couple of select workplaces, where they've really flipped the culture. You're no longer a hero for suffering in silence. You're actually someone who's a liability, because you putting our crews at risk, you're putting yourself at risk.

Dr Matt Brearley: And, when we do have a heat stress event, it's scary for all of us. It's very, very scary. It's potentially a life-changing event. It's not getting the work done. And so, are you really a hero for suffering in silence? We don't think so any more. So, we want a culture that's open. We want management of a workforce to be open to ideas, and open to the thought that productivity is not all about pushing harder in the heat, because we know productivity is affected, workers slow down. We can push them as hard as we want. They're in a, I guess, a heat haze, a heat hangover phase, where they're pushing, but there's nothing left, they're empty. The term, flogging a dead horse, comes to mind.

Dr Matt Brearley: So, we know a cool worker gets more work done. So, more rotation. It sounds counterproductive to productivity, but more breaks. You'll get the time back, you will get the time back, you'll see it through less slowing, less pacing of effort. We think there'll be less of those silly, or mindless, errors that occur when people are cooked. You'll be more productive. It's just having, I guess, it's having the commitment to seeing it through, and being brave. Because, they're current thinking in Australia at the moment, is not really around having breaks for productivity.

Spencer Howsen: Well, if you think about what you would do at home, say it's a hot day, and you've got to get the lawn mowed because people are coming over, do you just push on and do it, or do you stop lots, and keep drinking water, and of course you'd stop lots, don't you? If it's that hot. So, apply that thinking to the people you're responsible for.

Dr Matt Brearley: Yes. I would say, drink lots of water and cool down. So, jump in the pool, get in front of the fan, hop in the air con. You might even have a slushie. So, these are the methods we would use when we're freely thinking humans in our own environment. At work, it seems like, we put on the hi-vis, we go through the turnstile, and we switch off all of those methods, and it's all about being tough, getting the job done, and delivering for the client. And, I respect that. I really do. I think Australians are hardworking. We will have a crack. However, sometimes at our own detriment. What's more scary for me, at the detriment of our families. Because, what the survey is showing, is that workers are going home, and having interpersonal issues. They've got nothing left. They've used every bit of themselves up during the workday, and I'm guilty of this, and I've experienced this personally, so I kind of have a decent idea on this.

Dr Matt Brearley: My kids would come to me, I've just ridden home from work, it's silly thing to do, but it's over an hour ride home, and I'm cooked. The kids, "Hey dad, after school." No. No, no, no, no. You leave dad alone. Dad's got no... Uh-uh (negative). I can't deal with you. I can't help you with your homework. By the time I come good, because I'm just resting in the shade, not doing what I need to do, the kids are in bed. I haven't spent quality time with them, and we did this six or seven days in a row, and wonder why we have issues. So, as funny as it seems, one of the education messages for the workers that get home hot, is that you need to drop that core temperature.

Dr Matt Brearley: How can I do that at home? Hop in the pool. Okay, okay. So, you're saying it's okay to sit in the pool? I'm saying that, I don't know whether your family thinks it's okay. Well, why not jump in with them? You will cool down more rapidly. Okay. That's good. You might need to eat. Oh, so I'm going to have some food in the pool. Yep. Yep. Pay back that debt. What about a drink? Am I allowed to have a beer? Because they think, well beer is dehydration. This heat guy's going to tell me beer's definitely banned. And, I just follow the evidence. Evidence shows that, look, a couple of beers, and we say a couple, need to be really clear on what a couple means, because there's interpretation there. Let's say two standard drinks in the form of amber fluid. It might be around 660 mils, 700 mil of a beer. Not a massive dehydration effect.

Dr Matt Brearley: So, what we're seeing is that, there's fluid going in. There is mild dehydration effect, but it's kind of even Stevens for the 6 or 700 mil that goes in, you might lose that. So, if workers are really attached to the idea of having a beer after work with heat exposure, we'd say limit it, definitely, to no more than two. In the pool, cooling down or, having a slushie, or dropping that core temperature, and then you are able to be who you normally are, which is the person your family loves to be around. Your partner loves to be around you.

Dr Matt Brearley: Things just go better when we're not cooked. And, that's our message. The heat stress doesn't stop when you leave the work site. That turnstile clicks, you're still hot. We need to address that, as well.

Spencer Howsen: Matt, strikes me, there's, in the spirit of a holistic approach to workplace wellness and return to work, that, employers have an obligation to improve their overall health and wellbeing, and fitness of their employees, and surely that plays into this, as well, with heat stress. If you're fit, you probably deal with heat stress better.

Dr Matt Brearley: Yeah. Fit workers a more resilient in the heat. Having said that, they have their limits as well. But, undertaking your fitness, which is great for a whole range of reasons, but if you can get out and sweat a bit, you might be playing sport, it might be a game of touch footy, you might not see it as a heat acclimatisation event, or training. But, if you're out there sweating, having a puff, you're actually regulating your blood flow while you've got an elevated core body temperature. So, your body is constantly working out, how am I going to lose this heat? And, it's shunting blood, and sweat rates pumping up, et cetera. And these are the things you need to do at work to lose heat.

Dr Matt Brearley: So, we see these heat- acclimatised workers, they might be acclimatised through their work, but a lot of them are ready to redeploy to the heat. They might be FIFO. They might be on call to deploy to a disaster. They need to maintain heat acclimatisation, so they are resilient when they go back there. So, fitness is a massive factor in heat.

Dr Matt Brearley: And, another question I get asked is, what about age? I hear that, as we age, we're not that great at regulating our body temp. I feel that, when I was a young lad, I could do this, and now I'm older. And, that's true. However, it looks like fitness is the key regulator here. Because, we have masters athletes that are still training, still doing very, very solid workloads, and still able to handle heat in the same way that younger athletes can do so. So, it seems like, yes, age, there is a deterioration. It might be more of a fitness deterioration, because as we age we tend to be less active. So, is it purely age? I think it's age and inactivity that catches us. So, remaining active would allow you to be to remain somewhat heated acclimatised, and more resilient when that bad weather does come along.

Spencer Howsen: Let's hop in the pool, and have a beer together, shall we? Hang on, that sounded weird. Matt, thanks for being on the podcast.

Dr Matt Brearley: Thanks, I appreciate it, cheers.

[End of transcript]