Preventing Heat Stress in the Workplace with Tom Bernard

Heat stress is no joke.  Exposure to excessive heat and working in hot environments can cause Heat Exhaustion, Heat Cramps, and even Heat Stroke. The stress that heat puts on the body can be deadly if not identified and addressed.  On this episode, Thomas Bernard, PhD, CIH, CSP, and PE talks about heat stress, its effect on the body and how to prevent it.  Tom is a professor at the University of South Florida, College of Public Health and director of the Sunshine ERC a NIOSH Education and Research Center.  He has done extensive work studying the components of heat stress and has helped develop heat stress management programs for a variety of occupations.   Pete Koch: [00:00:03] Hello, listeners, and welcome to the MEMIC Safety Experts podcast, I'm your host, Peter Koch. Heat stress is no joke. Exposure to excessive heat and working in hot environments can cause heat exhaustion, heat cramps and even heat stroke. The stress that he puts on the body can be deadly if not identified and addressed. And even in its early stages, heat stress can deteriorate mental and physical performance to the point where minor hazards can become major exposures. Personal factors can also complicate the prevention of heat related emergencies. So a better understanding of how heat affects the body and how to gauge how hot is too hot are key. So on the podcast today with me is Thomas Bernard, Ph.D. in C.I.H. and Tom is a professor at the University of South Florida College of Public Health and the director of the Sunshine ERC, a NIOSH Education and research center. Some of Tom's other [00:01:00] certifications and qualifications are a Fulbright scholar from the Lambroso University in the United Kingdom. He's certified in public health. He's a certified safety professional, a certified industrial hygienist, a certified professional ergonomist, and a registered professional engineer. Tom's interests in heat stress include how clothing affects heat retention and dispersion, physiological monitoring, personal cooling methods and exposure assessment. He has done extensive work studying the components of heat stress and has developed heat stress management programs for a variety of occupations. Tom, welcome to the podcast. Thomas Bernard: [00:01:37] Peter it's great to be here and I'm looking forward to talking to you about heat stress and maybe just a tad bit of cold stress as well. Pete Koch: [00:01:45] That's fantastic. And, you know, as we were talking before the podcast, the heat stress piece really was supposed to be the main focus. But I threw a couple of questions in there at the end about cold. My background is really in the ski industry. But as we talked about before, there are some [00:02:00] heat related challenges, even in colder occupations. And cold has its own set of unique challenges that I hope we get to touch on just a little bit. So maybe at the end. So as we start to flow through here, why don't you tell me a little bit about how you got interested in heat stress and came to understand that it needed more further study? Thomas Bernard: [00:02:19] It can be, and in some regards, a long story. So it goes back to the fact that the early 70s, I was working at a department at the University of Pittsburgh Graduate School of Public Health, and this lab was famous for their heat stress work. And while I was studying metabolic demands of coal miners, I was in this department and actually participated in a couple of experiments that were going on at that time. So I think my introduction to heat stress was back when I was a graduate student. It continued at my time at Westinghouse, [00:03:00] where I was primarily interested in heat stress in nuclear power plants. And in fact, we developed some guidelines for the power industry that started with the nuclear field, but was eventually distributed out to all the electric power industry. I ended my move to the University of South Florida. That became a major interest in terms of a research agenda and that's been going on for more than 30 years. And I still remain fascinated by it. Pete Koch: [00:03:38] It really is a fascinating piece, just the effect. I mean, we're warm blooded creatures, so you wouldn't imagine that living in heat or working in heat would have such an effect on us. But it really does. And I think everyone listening can relate to being too hot at one point in time in their lives or maybe multiple times. So I think it's a good [00:04:00] time to talk a little bit about what the effects of heat stress are on the body. What does it do to us and what are some of the things that we might feel when we start getting too hot? Thomas Bernard: [00:04:10] And you know, you're right. So the first thing I want to point out is that, yes, this has been the experience of almost all of us. My caution to the health and safety people are because it's such a common experience that we often don't appreciate all of the risks. If you allow me a very bad analogy, it's like driving. We all drive. We all thoroughly under appreciate the risks that we undertake every time we drive. So in terms of response, we're warm blooded. That is true. But the other is we're fundamentally tropical animals so that we evolved in a way that we're accustomed to dealing with heat and we have natural physiological [00:05:00] responses. So the first of those is as we need to dissipate heat from the body. And by the way, heat stress is a problem of taking that internally generated heat and dissipating it out to the outside environment. So when we work, we generate heat that has to be dissipated out. The very first thing that happens is we increase our blood flow to the skin. So it's a cardiovascular demand and a cardiovascular response. Once it reaches the skin, then the most important way we have of dissipating that heat is then by sweat evaporation. So the second response is that evaporation of sweat or sweating and the evaporation of sweat and the other responses that's very kind of been there is that we do have an increase in our body core temperature as [00:06:00] well as an increase in our skin temperature. So the basic responses, our cardiovascular body temperatures and the sweating. Pete Koch: [00:06:11] So when those and those are all normal responses to us getting too warm and that that in itself is heat stress or getting warm, I guess. And then we go beyond our and our body starts to not be able to dissipate heat enough. And we get into some really negative effects then of heat stress, correct? Thomas Bernard: [00:06:32] Yes, that's correct. And I may drift into this and later in our podcast. So I want to make a differentiation. So stress will be those things that are external to the body that are causing the physiological responses. And then heat strain represents those physiological responses. So like stress strain relationships and in other areas of science. So the stress [00:07:00] comes from the work demands and the environment. The strain is our response back to this and that strain becomes excessive. Then it's manifested in the heat related disorders and these can be seen in the excessive demands on the cardiovascular system and will usually then classify those illnesses as heat exhaustion. So a cardiovascular insufficiency and heat exhaustion can go hand in hand. The other is that if the temperatures get high enough that we actually affect the central nervous system. So we affect the brain and the way the brain helps control our responses to heat stress. And then those will be heat stroke so that when we have a CNS dysfunction, central nervous system [00:08:00] dysfunction, then we have heat stroke. Heat exhaustion is serious heat stroke as a medical emergency. Pete Koch: [00:08:10] That's a really good differentiation there. And we're going to get in towards the end of the podcast about the responses to those, because those are a really it's a really key thing to understand, and especially when you get to that central nervous system shut down almost in the later stages of heat stroke or of that heat strain that you have to recognize it right away. And a lot of people don't. One of the things that I love to do is to actually coach. I coached high school girls soccer. We start our preseason early on, later in the summer, so early August, end of July. And we have some really hot days. And if you don't pay attention to how the girls are functioning during that practice, they can easily go into [00:09:00] a heat emergency. And you need to be prepared to manage that if you don't see the cues early on. And we'll talk more about that later on. But it's near and dear to my heart when we start talking about the responses to that. And so let's talk a little bit more about how, as you get into our bodies, inability to manage the stresses that are there, how does that affect the person from and we're talking about workplace safety. So how does that affect the person's ability to perform in the workplace? Thomas Bernard: [00:09:36] Ok, and I appreciate your example of soccer, so let me deviate for a moment and the fact that you started in early August and I presume that you step up your practices, you don't go for it right away. And we do this in order to allow our athletes and in your example and workers [00:10:00] and mine to adapt physiologically to heat exposure. So what we have is a process of acclimatization, and it does a couple of things. One is that there's an earlier onset to sweating, and that's important because then we get cooling going earlier. The other is that we have water and salt management physiologically. And so acclimatization helps manage and retain electrolytes and so that the sweat becomes more and more diluted so that it becomes almost water. And that's important. OK, so another physiological adaptation as we get exposed. What we find is that at the very early step ups is that we are actually making the transition for something that's thermally [00:11:00] comfortable up to where we reach what would be ordinarily an occupational exposure limit. We're already beginning to see an increase in unsafe behaviors. And in fact, there's some classic studies that go back and show that from a neutral environment where unsafe behaviors are minimum, not zero, to where we get to the widely accepted occupational exposure limits, we already see more than a 50 percent increase in unsafe behaviors. And following from the unsafe behaviors are accidents. And with accidents, we have injuries and resulting losses to the environment or our equipment. So this becomes important and it continues to go up as the heat gets higher. Then with that, we get starting to get a decrease in work performance [00:12:00] because we're taking some of that cardiovascular capacity that we would ordinarily use to support work. And now we're shunting that blood off to the skin in order to be able to cool ourselves. So it's clear that productivity will decrease with increasing levels of heat stress. And that has all to do with how the body's allocating blood. Pete Koch: [00:12:27] Since how the body allocates blood and how it responds to the environment in their own. Your own internal temperature is going to be different with every person. I imagine that heat stress will affect people differently. So it's not going to be it's not going to be a consistent response across the board like you would have with another exposure that might not be environmental, like fall protection or exposure to like a spinning machinery or something to that effect. Thomas Bernard: [00:12:56] Yes, so heat stress has a lot to [00:13:00] interindividual variability, so there's some people who, first of all, there's a small group of people or just heat intolerant, but let's set them aside for a while. Even in the range of heat tolerant, you're going to see a huge variation. Some people can deal with heat stress in incredible ways, and other people are going to be somewhat less tolerant, not importantly less tolerant. And we set our guidelines to protect those people with less tolerance. So not the intolerant, but people with less tolerance. And then that means those people with a with a high level of tolerance. Wonder why it is that we are saying that you're in a heat stress situation. And, you know, it's not only the difference between people, but even [00:14:00] within the same person, the day to day variations can be quite substantial. So you may be less tolerant one day and more tolerant the next. And we really don't know why that is, but probably has to do with recovery and just how our days vary a little bit. Pete Koch: [00:14:20] I can definitely see that with the athletes that I work with and because I can work with them every single day. And as a safety professional, I don't always get to work with the same group of people every day. Sometimes I do, but it's typically in a workshop or a training standpoint, and you're not going to have the same kind of physical demands that you would as an athlete on the field or a worker in a hot environment or highly physical environment that they might have that same challenge. So I can definitely see that in the athletes, you're going to have a group of people that are really, they're very tolerant to heat. They can manage it all the way through. And we do step our [00:15:00] practice sessions up. We start very slow and then we work our way up as we go through the summer. We step it up within the practice as well. So there's definitely a warm up period, a cool down period. And we don't just jump right into a lot of heavy physical activity so that we can work the athletes into that process or into getting warm and then getting their body used to be able to dissipate that heat as they go. What I've found with the athletes from the difference from day to day is there is a sort of an unknown component like you'd say, I just like I don't know why yesterday you were very tolerant to the same temperatures and today it's actually a couple of degrees cooler. The humidity is a little bit less and you are not responding in the same manner. Those are the outliers. I think consistently, though, what I've seen, especially with the younger athletes, [00:16:00] is their food management and their hydration management is relatively poor in that, you know, they might be drinking in practice. But what we typically tell them is that it's what you drank yesterday. It's going to help you hydrate for the practice today. And I think that's a key part. So in your studies, how does water management help someone deal with heat stress? Thomas Bernard: [00:16:29] Yeah, water management is incredible stuff. But and I want to caution your listeners at the same time. It's not the answer to all your problems. So this is one thing I like to point out. So on a job where there's a lot of profuse sweating, we recommend that you plan to have one quart of water per hour per person, and then that tends to be on the high end of [00:17:00] what the what will actually be drunk, but assures that you'll have sufficient water or other drinks available. But it's important to know that you probably cannot replace more than about six quarts of water and a working shift be at eight or 10, 12 hours. You're almost always going to have a deficit of water by the end of the day. And then what we really rely on is that you get that hydration completed during the off hour. So let's just assume it's a day shift, you know, in the evening and in toward the night that the water gets replaced. So you show up to work the next day. We always assume well rested, fully recovered and hydrate. That's what we pray for when they show up for work the next morning, Pete Koch: [00:18:00] And [00:18:00] that always happens. I mean, that's consistent, right? Everyone shows up well hydrated, well rested and prepared for the day. But that is an interesting part. I think education and again, getting into this, we'll get into it later as we talk about response and training. But education about, you know, if you're working in a hot environment, if you want to be prepared for that environment for the next day, what you do in the off hours really does affect you will affect your performance and response during the on hours as well. And it won't just help you at work. It will help you in the softball game after work or in the fishing expedition that you have over the weekend and any of that. So water management, education around that I think is good and great caution out there. It's not it's not the panacea. It will not be the solution for all the problems. And again, something that we'll talk about a little bit later on Thomas Bernard: [00:18:54] One thought I left hanging there. You have to be well hydrated [00:19:00] in order to be as tolerant as you're going to be of heat. So hydration doesn't give you any sort of superpower. It allows you to be yourself when you're dehydrated, you detuned yourself. And so we have to be careful that that water is permissive. But it's not an intervention that will make things better. We only want them to be hydrated. Pete Koch: [00:19:29] Excellent point. I like that water. Water is not a superpower. Perfect people. Yeah. And you hear it all the time. Drink water, drink water, drink water. Like it's going to make you better. It's only going to allow you to be yourself that sorry to repeat your words, but I think that's important for our listeners to take with them. And that's a really important point. Let's talk a little bit about now how you might measure heat stress and, you know, we all we all have that feeling of it's hot. Well, like, [00:20:00] how do we know what hot is? How do you measure hot? So in in my preparation for this podcast, the term Wet Bulb Globe Temperature came up in a lot of the research that I saw. And I have some understanding of that just from my years making snow because we used the wet bulb temperature to determine humidity and whether or not we could make snow actually above 32 degrees, which you can believe it or not. So how does Wet Bulb Globe Temperature? How does that get used in measuring heat stress? And how does it differ maybe from ambient temperature? Thomas Bernard: [00:20:37] Ok, so let me try that in a couple of different ways. So first of all, remember, I mentioned that the primary way that we lose heat is by sweat evaporation. And so that means that we have to have that. Pardon me for a technical term for a moment, but we have to have a gradient that drives that's sweat [00:21:00] evaporation. So I've got saturated water vapor on my skin and that drives to the environment. Getting away from the technical point then for a moment is that the drier the air, the more rapid that sweat evaporation is going to be in, the greater cooling I get. And then, of course, is the air becomes more humid. That ability to move water off the skin and into the air gets lower and lower. And by the time I reach one hundred percent relative humidity, I can no longer get sweat evaporation. And that really limit starts in and around 70 percent or so you start to see a diminishing return. So that is humidity is really the critical issue and not the air temperature. So when we talk [00:22:00] about the how hot it is in terms of the air and even to the extent that we talk about radiant heat, those are relatively small thermal loads on the body when we in comparison to the metabolic demands. Thomas Bernard: [00:22:16] So remember, I mentioned earlier, heat stress is a problem, getting internally generated heat out to the environment and the heat would be alone on the body from higher temperatures and radiant heat is probably no more than 10 percent of the metabolic rate. So it's not a big piece of it. And said the other way, sweat evaporation is that at least 90 percent of the heat loss there. So when we talk about assessing the environment, it turns out that we really want to wait that humidity. So the wet bulb temperature, the dew point are good [00:23:00] way. So when you listen to the weather station and they report, you know, they'll report dew point. Don't think about relative humidity, think about dew point. And once you start getting dew points that are up over 60, say, sixty-five degrees Fahrenheit, you're starting to report that it's humid. And by the time you're up to 70, you're clearly in a very humid environment. And so when people say it's hot, they may report dry, they may be reporting dry bulb temperature, but they're probably really reporting this kind of synthesized humidity and temperature. Thomas Bernard: [00:23:39] And if they're saying that it's hotter occupationally, it probably already is. All right. So that guidelines not too bad. And in fact, that might be that even though you're standing there, it feels a little bit comfortable. But when you begin to work and have to dissipate that extra heat, it's actually [00:24:00] going to be important. So WBGT getting back to actually your question is that that's wet bulb globe temperature. So wet bulb we now we've established is, is what is going to be sensitive to the level of humidity and the and the globe temperature is really a combination of the air temperature and radiant heat in the environment. So if you will, the wet bulb temperature represents our ability to dissipate heat to the environment and the globe. Temperature takes care of the convective and radiant heat load that we may have. And the WBGT is highly weighted to the wet bulb temperature so at 70 percent of the wet bulb temperature and 30 percent of the globe, and I like the WBGT [00:25:00] because it really represents in a very simple index, the ability of the body to dissipate heat to the environment and back our physiological responses will map to WBGT pretty well. Pete Koch: [00:25:16] So then as we as we start to look at the workplace, how do you measure that in the workplace? Typically you see thermometers in the workplace or you might get someone with a weather report in the workplace. I know that we had when we were working at the ski area to look at the wet bulb temperature, to determine humidity in the air and making snow on the other end. So the cold part of that, we had thermometers and different devices that would do that. But it wasn't something that you just ran out to the hardware store and grabbed. So what do you use to measure that? Thomas Bernard: [00:25:47] Yeah, well, in a minute, I'll tell you, how to go to the hardware store to get this stuff. But more likely, you need to have a high [00:26:00] quality instrument that will measure WBGT and there is a lot of cheaper things that pretend to measure this. So, so cheap is not going to be an answer. I'll provide you that answer in a moment. From a credible vendor a WBGT instrument is the usual way that a health and safety person will measure that in the environment. Globe temperature. Though, historically, is that somebody in the nineteen thirties, I think it was, went to the hardware store, got a toilet bowl float that happened to be a six inch copper globe copper sphere, put a thermometer into the middle of it and that became globe temperature. So, yes, you can go you're not going to go [00:27:00] to a hardware store anymore because they're plastic in the ellipsoid. But you can order online a fairly cheap six inch copper globe and make your own globe temperature. And in the same way, wet bulb temperature is you get a regular thermometer, you put a wick that can be something like a white shoelace that is then immersed in water and then allowed to freely evaporate to the air. So you can build, if you will, your own homemade WBGT device. That will be very good. And the thermometers have to be a good quality, but there are some not good thermometers that are readily available. Pete Koch: [00:27:51] I think you've just given me a new science project for our homeschooling group, so I think we might be doing that in a couple of weeks. See how that goes. I'll get back to you [00:28:00] if I need a list of supplies. So considering that, you know, so the best way then for an employer to measure heat stress in the workplace is WBGT. And I think you've described why, because it does represent the workers ability to maintain their thermal equilibrium. What other factors contribute to heat stress in the workplace and how do they affect it? Thomas Bernard: [00:28:28] So we talked about the environment and WBGT is a good measure of the environment and especially because we are concerned about the humidity. Obviously it once I say it out loud yet again, is the metabolic rate, the work demands.is the second job risk factor, because what's going to happen is whatever limiting WBGT there is, you're going to have to make it cooler and drier, [00:29:00] if you will, with the higher metabolic rate. So it's not going to be one value WBGT, but rather a relationship between the environment and the internal heat generation so that you can maintain thermal equilibrium. So the environment has to be more conducive to the sweat evaporation the harder you work and then. We have to worry about what they're wearing. So the third job risk factor is the clothing. Not most of all, occupational exposure limits are going to assume work clothes, so that would be something like a six ounce woven material, long sleeve shirt and eight ounce woven material pants. It could be coveralls as well as woven material that. But that's [00:30:00] the base unit. If you're in shorts. Or a T-shirt, you can afford to be a little bit higher than if you're in a double layer, coveralls are in the worst case, barrier clothing. Then we have to really change that threshold WBGT to match. Pete Koch: [00:30:24] It sounds as we start to look at the workplace itself and we have the humidity and the temperature and the WBGT in the environments, and then we have the work rate in the environments, it's compounded really not just by what they wear to work, but what they're required to wear for work, possibly personal protective equipment and things of that nature. So that's even going to be a contributor. And if you can't remove one of those, then it really comes back down to trying to mitigate the environment [00:31:00] or mitigate exposure. So maybe the amount of work time or time in the environment. Thomas Bernard: [00:31:07] Yes, that's correct. So and let me just go off on a tangent for a moment. It's almost always going to be the clothing that's going to be the big factor, a full face, negative pressure respirator, which is about the worst that you can imagine, really doesn't affect heat stress. You'll be very uncomfortable. But it won't affect your level of heat stress. The same can be said about gloves and shoes. That's where the major part of the body surface is covered. That's the question of what the PPE effect will be. And I totally lost track in your question. Pete Koch: [00:31:51] That's OK. I think just thinking more about the PPE itself, and I think that's a good point. And it's not going to be one particular piece [00:32:00] of PPE, but it's going to be the combined effect. And how much of the body is covered by clothing and PPE? Because, again, if you're if you're in a full-face respirator, but you are in a position where you can have more of your skin lightly covered instead of, you know, I was actually thinking about working in the woods and as a logger here in Maine in the summer, you might be in the woods. You're going to have chaps or you're going to have Cutter's pants on. And that's covering a fairly sizable chunk of skin with a fairly heavy fabric that's way more than. And that 12-ounce cotton woven pant that you're going to have. So it's going to have a different effect than, say, someone with minimal or clothing that's not that heavy wearing a full face respirator. So I think that's a good point. It's not just one piece of PPE or PPE itself, but a combination of all that are going to come together to drive [00:33:00] the heat stress higher. Thomas Bernard: [00:33:03] Yes, that's right. And then getting to the issue of mitigation, if we work just in the context of the job risk factors that we've been talking about, you have to pair up your actions so that you're on average, say, over the course of an hour, you get it within what would be the occupational exposure limit. So if you're wearing PPE, that's really interfering with sweat, evaporation, taking some time where you can dock that in order to be able to cool down will be important with the metabolic rate. If you're going to have periods of high metabolic rate, you're going to have to balance those with periods of lower metabolic rate or if you were in a very hot environment, periods where that environment will be a little bit cooler. But it's that combination of those three [00:34:00] things that are going to dictate how it is. You can mitigate that level of heat stress. Pete Koch: [00:34:09] I think that's a good way to think about it. And I think many times as I work with employers, they're really looking for one solution. And when it comes to heat stress, it's not just a single thing that you that you're going to be able to do. It's an advantage that you get to look at the combination of things and make some modifications. But it's not like, drink water or go to the shady spot that's going to be the solution. So there are different things that the employer is going to have to look at. Kind of brings up a point. I want to just kind of maybe jump back a little bit and talk about what factors contribute heat stress. And as I was thinking about outdoor activities, I was thinking about the flager on the side of the road, standing there all day in direct sunlight. How much does direct sunlight change [00:35:00] the impact of temperature? Thomas Bernard: [00:35:03] So the direct sunlight, you know, you'd rather be obviously in the shade than the sun, but the sun is going to make you feel warmer. So there's going to be a sensation because it's heating the skin. But the thermal load, if you will, is still going to be small compared to even the metabolic rate of just standing there. All right. And so it's important. And in the effect might be actually a little bit of a side effect is that you're warming the skin, which means you're going to bring a little bit more blood with the opportunity, especially standing, with the opportunity for that blood to pool down to the legs. And then you're going to feel faint and then you might succumb to a heat syncope, which [00:36:00] is a painting of that. All right. So, you know, just building on your example of the flagger they're going to want to walk a little bit or pump that blood back up to the heart, but the sun is going to make them uncomfortable. It's not adding substantially to the level of heat stress. Pete Koch: [00:36:24] Gotcha. And again, it's a combination of different things. Right. So thinking about that flager again and that static posture of being there, gravity always wins. So pulling blood down to the extremities, not providing enough oxygenated blood back to the brain, we actually talk about that from a fall protection standpoint. So, you know what happens if you're hanging in a harness for too long? How long are you going to be able to stay conscious in that particular position without being able to move? And it's one of the strategies for response after you've fallen to be able to move to be able to get muscle pump, to help your heart [00:37:00] move blood back up into the organs that need it to keep you, keep you awake, keep you alive. So, again, the combination of different things to look at, so movement to get the blood flowing and in this case, not only for oxygen, but to help dissipate your warmth back to all parts of the skin and not just the parts where the blood's hanging out down in the legs, so interesting. As we think about prevention, some more continuing down that track. Is there reliable data to support effective regulations around heat stress in the workplace and still trying to balance quality and productivity at the same time? Because I know that's always the thing. Like we have to have productivity, productivity, productivity and quality and quality. But if the person's not able to do it, you're not going to be able to manage either of those. So is there good data to support that? Thomas Bernard: [00:37:53] So the answer is yes, and then maybe some of your listeners aren't going to want to really [00:38:00] know the answer to the issue of productivity. OK, so let's talk about two parts of what regulations and I'd even broaden it to say what's good professional practice, OK, whether there's a standard or not. So one is that we're going to have to do exposure assessment. And is there good data to support that need that? The answer is yes. And the primary data asks the question, where can most people maintain thermal equilibrium? So how can they tolerate that environment for long periods of time? And you'll see these. Generally expressed as a WBGT limit at a given metabolic rate, and then the side of that is, of course, the increasing metabolic rates could lead [00:39:00] to a reduction. And what that limiting WBGT will be and then adjusting that for any kind of clothing that's being worn. So that's the exposure assessment. The point being is that it's well-established. We understand and know it. And it also follows the public health model that we're protective of most people. And we've already talked that there's a huge range. So we have to be careful that we don't fall into the trap of face validity where somebody will say, well, wait a minute, everybody, almost everybody can tolerate something higher. Thomas Bernard: [00:39:41] All right. But we don't know who those people are and we don't know how much higher than the other part is. What's the least you want to be doing to manage those exposures? And so I have my I have my list [00:40:00] of what you minimally have to do. And that falls into training, which is just, you know, accepted gospel truth in any occupational health and safety issue. I call them hygiene practices, but there are things that individuals can do to reduce their individual risk. Hydration is one example of hygiene practice. Arguably, acclimatization in terms of adjusting expectations is another hygiene practice. And then the third is surveillance. And that's really knowing what your environment is that a give them time because it does change during the course of the day. And it's also medical surveillance. It's the employer keeping track of even first day. So the data, so they can better appreciate what's happening in their workforce. [00:41:00] And then in the final thing is having an emergency response plan and if you will, I'm going to go I'm going to go back to your example of the harness and having fallen and now somebody is just sitting there. Thomas Bernard: [00:41:15] All right. I heard a safety professional probably 20 years ago say, talking about a fall protection program. And they said if your emergency response is calling 9-1-1, you're in trouble. And that is also the case in heat stress. If you think your emergency response plan is that somebody is going to dial nine one and you have nothing else to do, you're in trouble. Right. So it's those four components. It's having the training. It's practicing heat stress hygiene, it's doing surveillance, and it's having an [00:42:00] emergency response plan. And that emergency response plan, in my mind, also includes just first aid. Then I think in this way, what we've done is put in the backstop just in case we've made a mistake with our surveillance or we have someone who is heat intolerant because our usual standards don't protect everyone it protects ninety nine percent of the exposures or one percent of the exposures is once during a summer per person. All right. So that's not exactly overwhelming odds of protection. And so we do need to have that backup. We do need to say, OK, when that person slips through our protection, that we've got them covered. Pete Koch: [00:43:00] Let's [00:43:00] take a quick break. How hot is too hot, anyway, as we are hearing during this podcast, often it's not as simple as looking at the thermometer, humidity, airflow, the physical nature of the work and how the person is equipped all play a part. Not identifying and mitigating heat exposure in the workplace can cause serious or even fatal illnesses and injuries because workers will react differently to different conditions when hot environments are identified in the workplace. Employers must be equipped to respond appropriately for resources to help you identify and respond to heat stress exposures. Check out the heat stress resources from NIOSH through the Center for Disease Controls Web site CDC.gov and search heat stress. If you're a policyholder with MEMIC, you can sign into the MEMIC safety director and search for heat stress to find more resources there. Now let's get back to today's episode. Pete Koch: [00:44:00] So I like that as [00:44:00] we talk about those basic work practices, those are the essential things that we need to do to make sure that we can respond properly to heat stress in the workplace. So let's go back and take training just as one of those pieces, because I think training around heat stress is quite varied if it's done at all in in different environments. So let's talk a little bit about what might be important for an employer to do for training for their employees around heat stress. Thomas Bernard: [00:44:32] So training is going to be much like an employer would do for every other health and safety. So I always have to be careful to keep that perspective that they've got more than one problem to deal with. But once we work within that format is that you want the employee to be able to understand their hazards and then make rational decisions [00:45:00] about how to deal with those hazards to protect themselves and protect others. So you want to educate them to what are the factors that cause heat stress? So that's the environment, especially the humidity, the work demands. And if there are special clothing that they have to wear so they understand how these contribute, then having a little bit of basic understanding about what are the physiological responses so that there is a cardiovascular demand and there is a demand on water. We give up water from our body in order to cool ourselves, hence the need for hydration. So they've got that rationale for the hydration. Importantly then what they need to know or what are the signs and the symptoms of heat related disorders so that they can immediately recognize them. And we rely on people [00:46:00] to recognize them in themselves. But very importantly, we rely on people recognizing the signs in somebody else. And these then go toward the early recognition of the disorder. Then we can have the proper first aid or the proper response. So they need education on what these are. So that leads to what's the first aid, an emergency response plan. Pete Koch: [00:46:28] I think that's great and really kind of outlines well, it takes that training component and it incorporates all of those other components into it. So as an employer, really seeing it as not just a standalone piece, but if you're going to have if you're going to have a heat exposure within the workplace, then the training should include all of those components all the way up into. What do you do as an employee if you recognize this in one of your co-workers, which is a key part. And we actually [00:47:00] talk about that quite a bit on the cold side, like we talk about hypothermia, exposure, because a lot of folks, you're not going to know that you are in the early stages of hypothermia if you've got the fumble, stumbles and mumbles. So it really relies on your partner, your co-worker to understand what those symptoms are and start to address those we're going to touch. I'm going to ask you another question about cold stress here in a minute. But at the time of this podcast, there's actually a bill within the Maine legislature that's proposing setting a standard for maximum and minimum temperatures for indoor places of employment. And I just wondered, with all your experience around heat stress and how it affects the person and the variability of that, what are your thoughts about setting those limits and making them legislation for state? Thomas Bernard: [00:47:51] Again, I'm not opposed to legislation. I think, in fact, legislation and the actual rulemaking. The rules are [00:48:00] really very important. And I am a proponent of these. There's just a couple of things. First of all, I did a quick read of the brief legislation that's in front of the Maine legislature, I presume by maximums they're really thinking in terms of heat stress. And when they talk about minimums, they're really talking about cold. And these are really two different things. So let's talk first about heat, I think heat stress has to recognize that there are the three job risk  factors that we've been talking about and therefore, any exposure assessment needs to be framed in the way that we've been talking about. And you're not going to do that by saying, here's the temperature. If you do that, you're going to be setting a temperature so low, that everybody's [00:49:00] going to fall under it. And I don't think there will be very many people that are happy about that circumstance. For cold stress, if I can just go there for a moment and you started to allude to it. So I do want to come back. First of all, about cold stress, humidity no longer plays a role, so it air temperature and a bit air speed, but it's more nuanced than that. So you talked about hypothermia and hypothermia. We worry a lot about what is the temperature and then what is the clothing. And really to manage that cold stress exposure, we have to have enough insulation on to protect ourselves from hypothermia for any given temperature and work demand because remember, you're generating heat. And then what you want to do is preserve enough of that heat that you don't lose body [00:50:00] temperature, but then you need to allow the rest of it to dissipate. Thomas Bernard: [00:50:05] And so adjusting clothing, insulation and being in the skiing industry, you know how to do that. And I'm not a skier, but I imagine going up the chairlift, you're going to be all bundled up because your metabolic demands are low and then you're going to loosen up your clothing before you start heading down, because now your metabolic rate is high. So you have to adjust the effective insulation of that clothing. So this is key for managing hypothermia. Then the other thing we worry about is actually a localized effect. So it's getting frostbite or frost nip. And that then is what is the air temperature and what is the air speed, because that will dictate the rate of cooling of a patch of skin. So in cold stress, we have both hypothermia managed by clothing and we have local [00:51:00] effects that are managed by. Basically, if you will, managing the wind chill, and that works, the other thing that's worth noting from the safety point of view is, remember, we talk that the risk and the probability of an accident that could be an acute injury or loss of property or however it might manifest itself, goes up with heat and it does. But it goes up on the cold stress side and it goes up 10 times more. So cold stress in terms of having a risk associated with accidents is much more of a worry. It's I think it's a worry on the heat stress side, but it's an incredible concern on the cold stress. Pete Koch: [00:51:51] If I can ask a follow up question around that, why does it go up so much more? Why do the probability of accidents go up so much more [00:52:00] in cold than it does in heat? Thomas Bernard: [00:52:02] And I don't have a clue. Pete Koch: Fair enough. Thomas Bernard: But I got to tell you, it's an absurd phenomenon, right? It is there clearly enough that it's a problem. And I reported on it in an aluminum smelter, which is really a very hot place that if you're located in a northern location with a lot of air ventilation and smelters require a lot of air. When it gets to be zero outside or subzero, it gets incredibly cold in there at that time. And so we saw the accidents increase. But we're not the only investigators that found it. There were many others, too, who observed the same thing. Pete Koch: [00:52:52] I've totally found that in my experience with the ski industry as well, that I don't know that I could have, from my experience, say that it went up 10 times. But [00:53:00] I do know that even with a little cold stress. Your reaction time lessens physical reaction time, mental capacity at a much lower rate than I think for heat stress. I think your body can get warmer and still have a relatively functional processing capacity whereas you start to get cold and you start to shiver or you start to stop shivering, which is worse, you're not able to function anywhere near as well as you could just a few minutes ago before that that metabolic change happened for you. Thomas Bernard: [00:53:40] So if I can abuse something that I told you earlier, we're tropical animals. So we have learned to adapt, not learn to adapt. We have. Physiologically, the capacity to deal with heat being tropical animals, [00:54:00] we've relied totally on behavioral modification to manage cold. Pete Koch: [00:54:07] Yeah, that makes a lot of sense, tons of sense. So I guess kind of coming back to that legislative question then to have a hard and fast maximum and a hard and fast minimum from a temperature and just looking at temperature and they haven't even defined temperature in that particular bill that's there. I think there's probably a lot more work to do to make legislation functional for the protection of employees that still allows quality and productivity to live symbiotically in that. Thomas Bernard: [00:54:39] Thank you for bringing us back to the productivity. So let me get to that in a moment. Yes. You know, there's an incredible amount of work that staff and the Department of Labor are going to have to do to try to actually make this workable. That that was a fine action by the legislature, [00:55:00] if that's what they take. And other than, you know, in my mind, I read that by I say, well, they've given a command to the agency, develop something. The agency is going to quickly discover that this is a more complex process than that legislation would suggest. And that's fine. You know, we rely on the rulemaking process to discover those things all the time. The second part of this is that if you manage the heat stress and I'm also an expert on the cold side, but the cold stress, your quality of work is probably going to stay pretty close to the site. But what's going to happen is that you are going to have a decrease in productivity. And this is just simply inevitable because you're taking physiological [00:56:00] capacity and redirecting it from work to dissipating heat. You simply can't avoid it. So from a compliance point of view, I don't like thinking about compliance point of views, but it frames it well enough to maintain that level of compliance by necessity or your productivity is going to drop. How well you manage that heat will tell you how much your productivity is going to drop. And if you think you can beat that by saying, OK, we will just pay people a piece rate, their productivity is still going to drop. It might not drop as much, but I posit that I study again to show even increased rate productivity drops. But if you're not managing that exposure, what's happening is that the workers are taking on more risk and they're not doing it consciously. So that's not a willful taking on a risk. That's an unconscious [00:57:00] take on of risk that will lead to a higher probability of a heat related disorder and especially a heat stroke. Pete Koch: [00:57:12] I think that's a really good point. That's because it's a fine line, internal perception of where you are metabolically in your temperature. It's not easy. So as you're working, you're going to feel hot. But that moment that you go from feeling hot to not being able to manage the load anymore is a pretty fine line. And then going from that to heat stroke is an even finer line, and it's different for every person. So it really does make sense to try to manage that and knowing that productivity is going to have to suffer because it's a math thing. When you kind of get to it, what goes in has to come out. Otherwise the person is going to get hurt. That takes us into and I think it's a good lead into what [00:58:00] might be the appropriate medical response for heat stress. And if we start to look at it from. All right, so we've done what we can within the workplace, but this individual is not reacting well to the mitigation that we've had. And they're starting to experience heat exhaustion or heat stroke. And we're going to call 9-1-1. We know that's an important part of the response, but it's not the only part of the response. What's the appropriate response to heat stress once an employee has reached the point where they need intervention? Thomas Bernard: [00:58:33] So if you'll allow me to get away from the model that heat stress and the fact that now they're experiencing heat related disorder, which is the excessive strain, is that and pardon me, but that's just my obsession. So it's staged. You know, if it's a mild heat exhaustion it's going to be a symptoms driven identification [00:59:00] and the risk. And if you will, that's the early recognition. We like that. If somebody is reporting that they feel fatigued and they're thirsty and we like that, dizzy maybe a little bit of a headache, then they can stop work, go into as cool places they can find and drink. And chances are within 15 minutes they're fine and they're fully recovered and ready to go back to work. We like that. That's early recognition, early treatment. And if they go into a more advanced so a severe heat exhaustion, their body core temperature, we're not going to measure the body core temperature, by the way. And I'm not advising that, but it's going to be somewhere and still in the vicinity of what we would expect. But the cardiovascular demands are going to be huge. All right. So they're going to, again, [01:00:00] report headaches and tired. You know, their blood circulation is where we would want it to be. But now we're also starting to rely on signs, OK, they're going to be wobbly. They're just not going to be walking that straight line. We're going to notice that drop and physical capacity. Then we have to if they're not coming off the job to try to cool down, recover, we need to pull them off. Thomas Bernard: [01:00:29] Right. So this may be where we're starting to make bad judgments. And in the buddy system needs to see that and again, it's sitting in a cool place, it's drinking fluids and keeping a close eye in severe heat exhaustion. My friends in the sports area will take a towel soaked in ice water, put it over [01:01:00] their head and shoulders. And they use this not because it cools them better, but it helps give them an idea about the severity of the severe heat exhaustion. Right. So if they begin to feel better relatively quickly, then they know they're dealing with heat exhaustion. On the other hand, if they're not there, they're keeping an eye on the symptoms for heat stroke. And this is important now for heat stroke, nobody is going to report symptoms so much like you use the example of the hypothermia. The same is true for heat stroke. You're now not thinking this is now a central nervous system failing your brain is letting you down. And now this really requires your buddy to notice this. And in the cases that I've worked on, it's often gibberish that they're just [01:02:00] talking nonsense. They're going off and doing things. They don't know where they are. They just threw down your tools and left the job. OK, so behaviors that you just don't expect and you've got to open up your head to what are behaviors that are normal. And if anybody says I quit, the last thing you let them do is leave. Thomas Bernard: [01:02:23] All right. Because this is going, you know the “Bernard Pointer” is this looks like a heat stroke. Then the absolute best way to deal with that is put them in a cold water or ice water immersion bath. So you want to emerge and you'll see the old emergency medicine textbooks say, no, no, don't do that. Now, clearly, all of the evidence is ice water immersion is the best way to cool them down. Now, if you're out doing the timber harvesting that you discussed, [01:03:00] you know, hopefully you've got that one quart of water per person per hour. You know, who's sitting there and you probably have some left over. Hopefully it's cold. Well, you wrap somebody in a tarp and dump all of those in alright. You do whatever you can to cool them down. Right. And then you call 9-1-1. Notice that we're not calling nine one waiting that 15, 20 minutes, one hour for them to show up. And by the way, you want to alert them that you're dealing with a possible heat stroke so they can prepare to deal with that so that they can get them to the emergency room. So that's part of the plan. And when I'm working with but like right away maintenance, where they could be almost anywhere then knowing where you are and going over that [01:04:00] emergency plan, making sure you have cell phone service and everything else that you need, becomes part of that tool box safety meeting prior to any job that you begin. Pete Koch: [01:04:12] Those are great points, and it's interesting how a lot of those points are relative to really any job that has a significant risk of serious injury, whether it be fall protection or you're working around heavy machinery. Working alone is not the best thing, because, again, if you're risk assessment about the job that you're doing indicates that you're going to be in a high heat environment, you have the potential to not understand your own symptoms. So having someone there that can help is a pretty key part. And I do think that people do miss that part of their hazard assessment, like they talk about the environment, but they think about weather like high winds or something unexpected. But you can have a day that's, you know, in the high 90s and very [01:05:00] humid and very close and still. And you could have a significant heat load on the person and there could be a lot of heat stress. And then the person can experience a lot of heat strain from that. Great recap on the medical response there. Thomas Bernard: [01:05:14] And I just want to go back and reiterate about the buddy system, because when you do, you know, there's reports in the literature of these cases of heat strokes and a number of times that somebody wanders off and dies alone. You know, even though I'll tell people you never leave anybody alone. Pete Koch: [01:05:38] It's a great point. And that's an interesting point, too, because a lot of folks were like, oh, he just needs his space. He needs his time. Well, understand the environment that they're in and what they're responding to, because it might not just be they need a break from whatever they're doing, like you said. What's abnormal about their behavior? Is this something that they typically do or is this something very different than they've [01:06:00] presented in the past? And if it is, I think you said it was the “Bernard Pointer” don't let them leave. Right. I like that. Pete Koch: [01:06:07] So we're kind of getting towards the end of the podcast here. I do have a couple last questions. And one of them I well, it's a big question, so I'm not sure if it's fair, but I'm going to ask it to you anyway. So what do you know now about heat stress that he had wished you had known when you first started out when like when you were in the working with the mines and in the smelters and all that before you came to your position as being a professor? What did you what do you know now that you wish you had known then? Thomas Bernard: [01:06:36] Just about everything I know now. I wish I had known then I so I don't have a good answer. I've been asked this before and in some variation or another. And one response that I have is that every time I work on a case, for instance, I learn something new and I put that in my bucket [01:07:00] of knowledge. So I've got an accumulation of thirty or more years of this. Then, you know, I also think about this question all the time because I am a researcher that's beyond teaching. I investigate and we always are asking ourselves questions to this very day. We're rethinking what it is we know about acclimatization and the associated risks. What is it that we know about time weighted averaging and recently I've been more staging and thinking about severity. So we always think in terms of that hour after hour for an eight-hour day. But, you know, one of the things that we found is, for instance, of three degrees C I'm sorry, I think in degrees C increased, which is not huge changes the response of an individual from [01:08:00] being able to just thermal regulate to putting them into a situation where they're where they're at high risk for heat stroke doesn't it's not a big change from an upper limit to what can be a very serious outcome and how we can begin to do the risk assessment. So I'd like to say that you know every year I learn something new and I'm hoping, you know, next year, if you ask me that question, I've got more things to add to that list. Pete Koch: [01:08:32] I think that's awesome with all the knowledge that you have. And then just being open to that. There's something else out there that we just don't know that can shed a little bit more light on what you already know to give you insights. Some places. I think that's an awesome response Tom. So thanks for that. Is there anything that I should have asked you? But I didn't ask, is there something else that you want to reflect on for us? Thomas Bernard: [01:08:55] So the answer is we talked about the four [01:09:00] essential things. I want to go back and first put a context. If you suspect you have heat stress, those are the four things you need to do. That's the training the hygiene practices. Surveillance and having a first aid emergency response plan, when you get up to where you're reaching an occupational exposure limit, you also need to follow that typical hierarchy of controls. We're not likely to be able to do elimination and substitution, but there are engineering controls that are effective and administrative controls and there are personal cooling systems that work well. I want to go back, though, to the first four. And it's the hygiene practices, hydration we've really talked about. And it is about anywhere you go, people are going to talk about it. It is drinking cool flavored drinks doesn't [01:10:00] have to be electrolytes, but we know that they drink more electrolyte drinks than anything else. So I think that it just happened that there have been at least palatable water, its direction or self-determination, so that if you are feeling well, there ought to be a freedom to go recover. And most employers that I work with, you know, acknowledge that they do that. But it's getting the people to take advantage of that that tip, and especially if they're on piece rate, that the conflicting goal they ought to know about, if they've got chronic health issues, their personal care physician should clearly know that they work in a heat environment because there's not a disease or treatment that probably won't interfere with thermal regulation. Thomas Bernard: [01:10:50] The for acute illness, you know, the public health person to me to stay home because you're going if you go to work, you're going [01:11:00] to infect somebody else. But if you do remember that any nausea, you're not going to drink and you're not going to eat well, vomiting and diarrhea are going to dehydrate you. Fever is going to reset your thermal regulatory system. There's just a whole bunch of things that say you shouldn't do that and that a good diet, well balanced diet, no fad diets, getting plenty of rest don't do drugs are, you know, good advice. And I probably forgot something in there. But that gets I think, you know, an the acclimatization, adjusting your expectations, you're not going to run with everybody else. Until you get used to working in the heat. And even then, there's somebody who's going to be less tolerant than everybody else. So there's going to be somebody who can't keep up with everybody else. Pete Koch: [01:11:53] Those are all great tips. And some of them don't get pushed hard enough within the workplace. And I think that having [01:12:00] employees understand and then have a culture that gets them to feel that it is OK to not be first, especially when you're in that acclimatization process and that there's always going to be someone who is going to be better. It's not that you shouldn't try to be better, but know that heat is going to be in effect here. And it's going to effect everybody differently. And it's not something that you may be able to overcome in the same manner that someone else is. And then you really hit the nail on the head there, whether it's piece work or something else. But that permission to just say, hey, I've recognized in myself, that I've hit the limit and I need to go and cool down before I can come back and be a functional part of this job team again. And that's a really key part. And I do think that's missed often in our training or our discussions with our employees. You see it often when you walk into different places. And there's just something odd about the culture. They're like people are working super hard. But you're also looking at looking at people thinking [01:13:00] you probably need to step away from that machine for a little bit and take a break, reset and come back to it because you're bound to get injured. Good, good. Really good points there, Tom. Thank you for those. I think I could talk to you for another few hours, but. Well, I think we're going to have to end it here pretty soon Pete Koch: [01:13:18] If our listeners are interested. And I know they're going to be, about finding more out about heat stress and your work around heat stress, where can they go? Thomas Bernard: [01:13:27] That's great. I'm always willing to kind of help where I can. I'm not going to send you to my website because I've got to get it back right again. The systems people moved on a server behind on that. But there's some materials that I can make available. Pete Koch: [01:13:47] There are other organizations like NIOSH that have done research on heat stress and how to prevent it within the workplace, too. So but there's other places to go as well. So [01:14:00] besides NIOSH, are there any other organizational places or websites that folks can go that you would recommend? Thomas Bernard: [01:14:07] Yeah, a great resource is NIOSH. They've revisited their criteria document three and two types, so they issued one, revised it once and revised it again, that's almost unheard of. So it really reflects, I think, the current thinking. Their most recent revision is 2016. So anybody serious about heat stress management, she should avail themselves of the NIOSH criteria document dated 2016. If you just do an Internet search, you're likely to find it. OSHA and NIOSH have materials on heat stress on their websites and I think they're generally pretty good. My only hesitation [01:15:00] and it’s a modest hesitation is that they will in some areas talk about stages of heat reflected in the heat index. And I think their ideas generally right. I'm not sure that I totally agree with their thresholds. I think a couple of them are too high in a couple of them were too low. But the idea, you know, the content for training programs and heat alerts and all of the things that they discuss are really very sound approaches, because I've been on the physical agents committee and the ACGIH. But I'll remind you that the ACGIH has a TLV for heat stress and strain and associated documentation so members can easily get a copy of this and nonmembers it is available for purchase. And I'll [01:16:00] give a heads up. We're in the process of doing a major revision not of the thresholds, but the associated documentation. So in a year I think it's going to be even better. Pete Koch: [01:16:12] What we'll do is we'll take those, we'll take those documents and we'll put those links on to the podcast website. So you go to MEMIC.com/podcasts. They'll be able to see the transcript from this and then they'll also be able to grab those resources. I think that's great. You spent a ton of time with us and I really, truly appreciate this conversation. Tom, it's been fantastic to have you on and share your expertise with us. Really. Thomas Bernard: [01:16:39] It was fun to do it. So I appreciate the opportunity. Pete Koch: [01:16:45] And Tom, thanks again for joining us. And thank you to all of our listeners out there. Today on the MEMIC Safety Experts podcast, we have been speaking about heat stress with Thomas Bernhard, Ph.D. Tom is a professor at the University of South Florida College of Public Health [01:17:00] and the director of the Sunshine ERC a NIOSH Education and Research Center. If you have any questions or would like to hear more about a particular topic on our podcast, email me at [email protected]. Also, check out our show notes at MEMIC.com/podcast where you can find additional resources as well as our entire podcast archive. And while you're there, sign up for the Safety Net blog so you never miss any of our articles or safety news updates. And if you haven't done so already, I'd appreciate it if you took a few minutes to review us on Stitcher, iTunes or whichever podcast service that you found us on. And if you've already done that and you subscribe, thank you. Because it really helps us spread the word. Please consider sharing this show with a business associate friend or family member who you think will get something out of it. And as always, thank you for the continued support. And until next time, this is Peter Kotch reminding you that listening to the MEMIC Safety Experts podcast [01:18:00] is good, but using what you learned here is even better.