First-person perspectives on the world of work
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The Future of Work Podcast

Episode 42
Heat stress

Heat stress – how are we going to live with it?

18 July 2023

The summer of 2023 is recording some of the highest temperatures on record, for our entire planet. These new records have significant consequents, not just for the environment but also for human life, including the world of work. Heat stress is a growing issue. It affects not just individual workers – particularly those who work outside – but also businesses and the overall economy, because higher temperatures affect productivity. Working hours, routines, equipment, and regulation may all have to change.

So what are the consequences of these higher temperatures for the world of work? How will governments, businesses and individual workers adapt?




Hello, and welcome back to another edition

of the ILO's Future of Work podcast.

I'm Sophy Fisher.


The beginning of July was the hottest week

on record for our entire planet.

This followed the hottest June on record.

Those figures come from the World Meteorological Organization,

the UN's agency that looks at weather and climate, among other things.

Clearly, these consistently hotter temperatures

have enormous consequences to the environment.

They also have very serious consequences for the world of work,

because heat stress affects not only workers,

particularly those who work outside, but also businesses,

because higher temperatures are associated with damage to productivity.

If we are going to have to learn to live with higher temperatures,

what does that mean for the world of work?

With me is Nicolas Maître.

Nicolas is an economist in the ILO's Research Department,

and he is also one of the lead authors

of a recent ILO report on heat stress.

Nicolas, welcome.

Thank you very much for finding the time to join us.

Thank you very much for having me.

Let's start at the very beginning.

Your report is about heat stress.

How do you define heat stress?

What actually is it?

When we talk about occupational heat stress,

we talk about a situation where it's too hard to work,

or at least too hard to work to a normal intensity.

It depends not only on temperature, but also on humidity,

or the solar radiation,

and it endanger the safety and the health of workers

by increasing the risk of injuries and heat-related illnesses.

A natural defense to cope with heat stress is to take more breaks,

limit the numbers of working hours.

All these measures have the consequence of reducing the productivity.

What kind of temperature does heat stress start to occur at?

What's sort of ambient temperature?

The estimate shows that work productivity already slow down at temperature

above 24, 26 degrees, and that 33, 34 degrees,

worker performance can drop up to 50% depending on the job,

but in physically demanding job, for example.

Right. Because some of the temperatures that the WMO,

the World Meteorological Organization,

has been talking about are over 35, getting on towards 40,

so that would be very serious.

Exactly. Yes.

Does heat stress only occur if you're working in direct sunlight?

No. It can occurs in shade,

or even inside, in some factories.

For example, if the factory is not properly ventilated,

or there is no air conditioning,

or in other case where there is heavy machinery or protective clothing,

it can occur in this kind of context.

Okay, because that's interesting

because the sectors that have most been talked

about, in association with heat stress, are agriculture.

Where obviously, a lot of people are working outside, and construction.

We've seen quite a lot of cases related to that.

From what you're saying, it isn't just limited to those two industries.

No, it is not.

Obviously, broadly speaking, agriculture and construction

are the most affected sectors because, for example, in our estimate,

we have seen that agriculture account for 60%

of the productivity loss at the global level.

In fact, it can occur in all jobs

that requires to work directly under the sun,

or if it require protective clothing, or if [crosstalk]

For too long hours, I suppose.

Exactly, or physical intensity.

If there are physical intensity [crosstalk]

You're moving a lot of things, perhaps,

and wearing protective clothing to do so.

Exactly. We can think about jobs in the sport industry,

but also public servants, such as police officers or militaries,

that can be affected also by heat stress, but also street vendors,

in the service industry, can be affected.

Of course, street vendors are very common in--

They're almost ubiquitous in developing countries, right?

Exactly. Often, they are self-employed, and for self-employed,

the loss of productivity result directly in a loss of income,

and therefore, a loss of livelihood reduce.

Yes. This is one of those factors where heat stress is already starting

to affect those who have the least ability to absorb the consequences.

Yes, exactly.

The least capacity of adaptation, in a way.

Also, when looking at the countries that are affected the most,

we've seen that country most affected

are often those with decent work deficits,

such as a lack of social protection,

more prevalence of informal workers, and more working poor.

So, it's also a matter of social justice,

and it's a matter of increasing inequality

among countries and within countries.

Should we also regard this

as an occupational safety and health issue?

Because the countries that you're talking about,

the ones who often lack decent work, lack social protection and so on,

often have some of the poorest ratings

when it comes to occupational safety and health, too.

Yes, it is definitely an issue of occupational safety.

It's an occupational safety hazard.

Not only because there is this direct effect of heat stress,

which results on discomfort, injury, and illnesses for the worker,

but also because it has indirect effects,

because it increases the risk of injury.

The workers that are experiencing heat stress,

you can think about sweaty palms, or also foggy glasses,

but the dizziness also can result in an increased risk of injury.

-Accidents, I suppose-. -Exactly.

because if you have sweaty palms things are likely to slip,

and if you're experiencing dizziness,

you may either make bad decisions or make a mistake

with a machine, something like that.

-Exactly. -It doesn't just affect you,

it could potentially affect your co-workers.


A lot of these workers don't have injury insurance benefits,

so they are more at risk of these events.

Of course, I was going to ask you, we've been talking

about the consequences for individual workers,

but with those kind of issues related to heat stress,

there's obviously a consequence for employers as well.

I think one of the things that you said in your report, wasn't it?

Was about the effect on productivity?


In this report, we estimated the productivity loss at the global level,

but also for every country in the world, of heat stress.

We've found that in 2030,

the heat stress will result in a productivity loss

of 2.2% of all the working hours at the global level,

which is equivalent to 80 million full-time jobs at the global level.

Of course, this is not what we need

at a time when the global economy is trying to recover from COVID,

and even still from some of the consequences

of the financial crash more than 10 years ago.

Exactly. Yes, and the situation has worsened since 1995,

because in 1995, our estimates point

toward a loss of 1.4% of all working hours.

In 2030, it'll be 2.2% which is a significant increase

in the effect of heat stress.

Okay. What can we do about it?

Let's start with workers and employers,

because they are probably the people who can react most quickly now,

since this phenomena seems to be happening quite quickly.

What can they do?

Yes, workers and employers,

they are best pleased to take action to protect

the workers and implement adaptation measures.

More concretely, those action can be, for example,

increasing the number of breaks,

but also adapting the access to water for the employees,

adapting the working hours, but also increasing the workers' rotation.

Another possible measure is with respect to the clothing,

adapting the clothing of workers,

or if we look at the actions that can be taken

directly from the employees themselves, the workers themselves,

is all the heat reducing activities.

For example, drinking regularly, having a self-health check.

Monitoring your colleagues.

Exactly. Monitoring the colleagues are very important,

and raising concerns when you notice some

-Somebody-- -- symptoms of heat stress.

Right. What about for employers?

That presumably would be to help workers

introduce these kinds of measures.

Yes, exactly.

They have to create work environment where workers can feel safe,

and can raise their concern.

Also, in term of infrastructure, access to water.

This is also the role of employers, but also employers should also

Give access to cool spaces and shade and things like that.

-Yes. -Reconsider clothing?

-Exactly. -Those kind of things?

Provide risk assessments also, with respect to heat stress.

We traditionally have associated heat stress with hot countries.

Countries in the Middle East and the Gulf,

countries in parts of Africa and in Asia.

Where hot temperatures are, in some cases,

something that's experienced year-round, and they're very used to it.

They have adapted, over a long period,

and they've adapted their working routines, but now,

it's clear that heat stress is no longer just

an issue of what we would think of traditionally, is the hot countries.

It's an issue for more temperate countries, too.

Do you think there's something

that more temperate countries can learn from hot countries?

Yes, for sure.

First, all the evidence suggest that it's becoming

a real problem for temperate countries, but the problem, as you said,

is not the same.

While in Southeast Asia, for example,

the problem is present more or less whole year-round, in Europe,

it's really a punctual problem that occur

during heat waves in the summer.

I believe that the adaptation measures

also should consider these differences.

While in hot countries we can think

about implementing sustainable adaptation measures, in temperate countries,

we might think of adaptation measures that are triggered, for example,

by a certain level of temperature.

Right. This is where the governments might come in.

Setting these kinds of levels

which might trigger a different set of measures.

Is that the kind of thing that governments could do?

Exactly. The role of the government is very important in providing,

first, the information.

This also relates to this level of temperature

for the triggering of these adaptation measures,

but it can also create an appropriate regulatory framework

within the countries to tackle the issue of heat stress,

and also invest in infrastructure,

regarding buildings and also warning systems,

early warning system that allows us to react quickly to the issue.

I imagine that somebody might say, "Oh, this is going to be expensive,"

but I imagine that you would say,

"Well, this is not a problem that's going away."

Yes. Exactly.

Time to invest. -It might be expensive,

but the losses of productivity are also expensive,

and are also increasing dramatically.

I just want to point out

also that our estimates are quite conservative,

because it uses a scenario of 1.5 degree

increase by the end of the century.

-In climate warming, yes. -Exactly.

Which we know- We may not be able to stick to.

Exactly. It's likely to be more than that.

The losses of productivity are likely to be even more important than that.

Hey, when you started working on this report, it was a few years ago.

People didn't really talk about heat stress.

Suddenly, within a couple of years, it seems to be with us every summer.

Have you been surprised at how quickly this appears to have come on?

That's true. When we started, there were very few reports, or research,

or even the media coverage was not the same.

Now we see numerous articles, numerous reports,

and in the media it's all over.

I think it is because it's unavoidable. It's here.

We see our colleagues, our friends, our family experiencing the issue,

and also when there is dramatic death of workers,

it really strike people more.

Yes. You are continuing to work on this topic, aren't you?

Yes, of course. We are still working on it.

We are currently developing a research

for a forthcoming report on the issue. [crosstalk]

We can expect to get more detail on this,

which I think will be very useful.

I'm sure we will be coming back to this topic again.

If anybody wants to look up the report that Nicolas worked on,

it's called ILO, Working on a Warmer Planet:

The Impact of Heat Stress on Productivity and Decent Work.

You can find it on the ILO's website if you just do a search.

Nicolas, thank you so much for joining us.

Thank you very much for having me.

Good luck with the rest of the research.

Thank you to you for listening in, and I hope you will join us again soon

for another ILO podcast on the Future of Work.