The Safety Lab:  The Impact of Excessive Heat

[00:00:00]
Today we’re talking about something really topical for the summer, excessive heat, and the incidents of occupational injuries.

We all know that feeling when the summer heat kicks in, you’re thinking about vacations, maybe an ice cream or two, but there’s a significant consequence when it comes to rising temperatures that doesn’t always get the attention it deserves, how it impacts your safety at work. Think about it. Even just feeling a bit sluggish from the heat can be distracting when you’re trying to stay focused and avoid accidents.

[00:00:30]
Yeah. I think that we often underestimate just how much heat can affect us, and so there’s just like direct illness, heat stroke, that sort of thing which is familiar. I think there’s subtle ways in which heat can increase the risk of injuries on the job.

[00:00:46]
Absolutely, and that’s what we’re digging into today.

We’ve got a fascinating piece of research here from the WCRI, that’s the Workers’ Compensation Research Institute. It’s called The impact of Excessive Heat on the frequency of Work-related Injuries. Our mission in this deep dive is to unpack the study and see how these increasing temperatures might be creating risks in the workplace that you may not have considered.

Like, does really hot weather lead to more people getting injured while they’re working?

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And the study gives us some pretty compelling answers. Based on a substantial amount of real world data,

[00:01:21]
it really does. They looked at actual workers’ compensation claims. They combined that with daily temperature data, specifically May through October.

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So like summer, the summer, warmer months.

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Right. Exactly. And they did this for six years. So this was a big study from 2016 to 2021, and they looked at data from 24 states. So we’ve got a large sample size across a lot of time. The study kicks off by making an important distinction about the types of injuries related to heat at work.

[00:01:49]
They break it down into what they call direct and indirect injuries. Direct is like the obvious ones. Heat stroke, heat exhaustion fainting, heat cramps.

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That makes sense. Those are the ones that everyone thinks of. But you also mentioned indirect injuries.

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Yeah. So the indirect injuries happen when heat impairs a worker’s performance, and so it affects their ability to like say, perceive risks.

Maybe it affects their physical coordination or even just like their concentration in decision making. And so imagine like someone working on a roof on a really hot day. They might get more fatigued and maybe their like judgment is a little off. And that could lead to a fall. I. But when that gets coated, it’s coated as a fall and not specifically a heat related incident, even though clearly heat played a role.

[00:02:38]
Ah, or maybe someone could trip because they’re feeling lightheaded because of the heat, or a driver misjudges something because they’re feeling off, distracted by how hot it is.

[00:02:49]
Yeah, those are, yeah, those are all great scenarios. So the heat is a contributing factor or like a background factor. Even if it’s not the immediate cause written down on the injury report. And so this suggests that the true impacts of heat on workplace injuries might be much broader than just those direct heat illnesses that are clearly tracked on injury reports, right?

[00:03:11]
It’s more about how heat can subtly chip away at your ability to work safely.

So with these two types of injuries in mind, the direct and indirect, like we went over, what did the study find overall when they crunched all those data points?

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Well, the striking part is that the study concluded that the likelihood of a work-related accident goes up by 5% to 6% when the maximum daily temperature climbs above 90 degrees Fahrenheit.

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Wow. Okay. So 5% to 6%. That’s significant, but where are we comparing this? Like what’s the baseline here?

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Yes. The baseline is they compare it to is temperature in a more comfortable range, like a 65 to 70 degree day.

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Okay, so to put that in perspective, if a place normally has say, a hundred injuries, when it’s at that comfortable temperature, this study is suggesting that they might see 105 to 106 on those really hot days.

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Yeah, it’s a significant jump in potentially preventable incidents.

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And you mentioned this finding it’s not totally out of the blue. Other researchers have pointed this out like this. I think this study was done because they were seeing sort of these trends, so they wanted to gather these bigger data points.

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So, in this study, the researchers reference past studies that have also found a clear link between higher temps. And work-related injuries.

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So this WCRI study is adding more weight to that evidence and reinforcing what others have been finding.

Okay. So what about those days that aren’t, scorching hot, but still pretty warm, like say high seventies or eighties? Is anything happening in those temperatures, before it gets that above 90, like you mentioned?

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Totally. They did look at that and even in moderate heat range, so this is like that 72 to 90 degrees Fahrenheit. They still observed an increase in injuries somewhere between 1% and 5%.

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So it seems like even what we might just consider a typical hot summer day, can still have a measurable effect. It’s not just about those extreme heat waves. And it suggests that we really need to think about heat safety, even on days where it doesn’t necessarily break records and you might be feeling like it’s a normal day. Just imagine the impact of that heat and how it might vary across the country.

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Yeah. So this is a US study, right? Did they look at different regions or different parts of the country?

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They did, yeah. This is where it really gets interesting. They broke down the findings by the regions, specifically the South, the Northeast, and the Midwest. And the impact was quite different depending on where you looked.

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Where did they see the biggest effect?

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I think that we could all probably guess it’s the south. With maximum daily temperatures that went above 90 degrees Fahrenheit. They found a 9% to 11% increase in work-related injuries there.

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Wow. That’s like double the average that we were talking about before.

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Yes. It’s a pretty substantial jump. And it might not just be because they have more hot days.

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What are the other factors?

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So it could be that there’s some types of industries that are prevalent there. There’s not as much existing infrastructure for cooling or heat mitigation. There’s many things that go into that jump in work related injuries.

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Huh. That is so interesting. The study looked at other regions. What about like the Northeast or the Midwest?

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So the Northeast did show a notable impact, though it seemed to not have quite as much of an increase as the South. They found an 8% increase in workplace injuries when the temperature hit 90 to a hundred degrees.

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Yeah. 8% increase. That’s still significant.

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Right. What did the study say about the Midwest?

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Midwest saw a smaller increase around 2% at temperatures between like 80 and 95 degrees.

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So a bit of a lower range there, but it’s fascinating kind of seeing those regional differences. It really makes you wonder about the types of work in these places and maybe how used to the heat people are and if that makes a difference.

And speaking of types of work, did the study dig into how those different industries are affected?

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Yeah. Variations across industries were remarkable. Construction clearly stood out.

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Oh, I can imagine. There’s a lot of workplace injuries when it comes to construction. What did they find?

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14% to 20% increase in work-related injuries in construction when the temperature went above 90.

[00:07:32]
Wow. 14% to 20%.

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Yeah. It’s like a huge jump. Almost one in five more injuries simply because of heat.

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It’s not entirely surprising when you think about it. So much of construction work is outdoors, heavy, physical labor, direct, prolonged exposure to the sun. That’s gotta play a huge role. Were there any other notable industries besides construction?

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Yeah, they also looked at. Manufacturing services, trade transportation. And in those sectors, they found more matter increases. But I wanna stress, even when we’re saying moderate, this still is like range of four to 7% of additional workplace injuries. So these are often industries with a mix of indoor and outdoor work.

Or maybe indoor places like a manufacturing floor, the sites that generate their own heat.

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So it’s definitely not just traditional outdoor jobs that are being affected. When we think about that, we always think about climate change too. But heat seems to impact a wide spectrum of work environments, and I could see how.

Being on that hot manufacturing floor could make a difference. So the study also looked at different types of injuries that were more likely to happen when it got hot, right?

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So they categorize injuries into two main groups. The first, which is like traumatic injuries, fractures, dislocations, cuts, bruises.

These are like sudden impact type injuries. And then the second group was sprains and strains. And so they found that traumatic injuries tend to increase more with rising temperatures compared to like sprains and strains.

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That’s interesting. I wonder why that is. Maybe the heat induced fatigue or that decreased concentration leads to more of those sudden accidents like slips, trips and falls. Did those differences in the two different categories vary by region as well?

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When they broke it down regionally yeah. So they found the South saw bigger increases in both traumatic injuries and sprains and strains when it was hot. The Midwest mainly saw an increase in the traumatic injuries linked to heat, and the Northeast experienced increases in both categories. Similar to the south, though less pronounced.

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So even the type of injury seems to be influenced by both the heat and where you are geographically.

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Lots of interconnected factors, right?

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Now, the study touches briefly on things that might influence how much heat contributes to injuries, right? Like mitigating factors.

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They bring up a few key things. One is acclimatization, and so this is the idea that. A worker just gets used to working in hot conditions, and so someone new to the heat like might be more vulnerable. And then secondarily, they also highlighted the importance of cooling infrastructure: so air conditioning, ventilation, access to shade, all of that can help reduce impact.

[00:10:18]
That makes sense. I think the study also mentioned some rules and guidelines around heat safety. They mentioned OSHA’s recommendations on guidance, including something called the 20% rule, which is about how to gradually acclimate new workers to the heat exposure that they’re going to have on the job.

They pointed out that while there. Isn’t a comprehensive federal heat standard. Some states have stepped in like California, Washington, Oregon, Colorado, Minnesota. They’ve all implemented their own specific heat safety regulations. And also, interestingly, they noted that some states like Texas and Florida have put limits on local governments creating their own heat rules.

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So like, preventing cities and counties from making stricter rules?

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It seems like it, it’s definitely a varied landscape across the us. A real patchwork really. But like any good research, this study is upfront about its limitations and things that you should keep in mind.

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Yeah, there’s some important context here. First, that while they looked at a lot of claims, the study is still using what’s called a convenient sample, meaning it represents a large chunk of claims in the state, but not necessarily every single claim. We’re talking more like, like 40 to 80%. And so it’s not like a perfect picture of all work injuries.

[00:11:31]
Okay. Got it. And they’re using temperature data at. The county level, which does have some potential drawbacks.

[00:11:39]
Yeah. So they used maximum daily temperature recorded for the whole county, aggregating temperature information. This has some limitations especially in really large counties or places with elevation changes or coastlines, places where temperature could be different from one end of the county to the other. You can have different microclimates within the same county. So, a single county temperature might not capture everything perfectly.

[00:12:08]
Right. And one other thing, they mentioned that the employment data that they use to calculate injury rates was annual, not monthly. So that really wouldn’t capture big seasonal hiring swings perfectly.

[00:12:21]
And yet despite those limitations, the core message seems clear, excessive heat. Has a significant impact on the frequency of work-related injuries. And critically that impact goes beyond just obvious direct heat illnesses.

[00:12:37]
Including those indirect injuries caused by impaired performance. We saw those big increases, especially in the south, especially in construction.

Given what we keep hearing about more frequent and more intense heat waves. these findings seem to underscore the growing importance of this issue, don’t they?

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Yeah, I, the study highlights the increasing need to be proactive about addressing and mitigating key risks in workplaces and on work sites.

[00:13:05]
And if you haven’t heard our podcast episode that came out earlier this month with Zach Pacillo on the midyear regulations update, we talked a lot about the new OSHA heat rules.

So for the listeners out there, consider this, how do these findings connect with the bigger picture conversations around workplace safety, adapting to climate change, and the wellbeing of workers at different jobs?

Where do you think these effects might be most pronounced? Or where might they be being overlooked? Perhaps specific industries or maybe in regions that are just starting to feel this more extreme heat and maybe haven’t had the years to experience the changes that are going on?

[00:13:41]
Yeah, I think it is just really worth thinking about how different workplaces are handling heat right now, or maybe aren’t handling it. And are current safety measures enough based on this new evidence and what else might be needed?

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I think understanding this data and getting these numbers out there is really the critical first step towards creating safer, healthier work environments as things continue to change.

Well, that’s it for our deep dive on excessive heat and its effect on workplace injuries. A huge thank you to everyone listening for joining us today. Keep those brains engaged and we’ll catch you in the safety lab next time. Stay safe out there.