Oh, Baby, It's HOT! How to Keep Workers Cool?

I would look at keeping the people and the heat-producing equipment away from each other, as soon as I had replaced all the tungsten lighting with something more economical. Then, I'm funny that way.

Our factory floor consists of 10 vacuum chambers, each with retractable ovens. These are baked for several days at 380°C then the ovens are raised. The final processing happens with the chamber at about 100°C when the operators have to use manipulator arms through the chamber walls. No chance to escape the heat there. I'd like to offer moral support but have to retreat to my air conditioned office.

Sounds like the boiler room on RN carriers in the 60's & 70's, when serving in the Far East!!!

I came back 20 Kg lighter than I am now.....I weigh 89 Kg today.....I was 5' 11" at 17!!! I've shrunk a bit since then!!

.....and I ate well, the food was really good at that time, on that ship.....

Snap!!

They got rid of a few of those wretched things around the world..........They should have sold them to their enemies!!

I had a temporary posting to the Melbourne in the RAN.........three years later I managed to get off it.

The interesting thing about them was that they were originally designed for the Murmansk run, (North of Russia) and here we were operating in the tropics..........lovely........NOT.

The RN got rid of eight of those light fleet aircraft carriers and Australia bought two of them. The Melbourne was the ex "Terrible".........I don't know why thy changed its name.........it was still terrible!!!!!

I don't know about you, Andy, but I don't think you know "hot" until you served on one of those things!!!!

I was on the Triumph. Colossus class

HMS_Triumph

HMAS Sydney was a Majestic, but both were light fleet carriers....and HOT!!!

HMS_Terrible

I would have to look at the floor space and equipment locations, work stations etc....to design an air flow system to exhaust the heat and supply cooling air....Have you had an HVAC specialist examine the situation?

http://www.coolrelief.net/Ice_Pack_Accessories.html

Have them work at night.

I suspect that the scale of the solution lies somewhere between "cooling suits" and "cooling all the air in the facility."

For instance, must every part of the process equipment be accessed (or accessible) at all times and in all cases? In the majority? Probably not. Where possible, thermally isolate these parts of the equipment from the workers' immediate environment and vent that heat elsewhere, or enclose the workers' immediate work area and cool that instead; this area possibly also containing heat-producing parts of the process equipment (manually pulling hot castings out of moulds, for instance). Cooling a whole building has never make sense in cases where most of the volume is not actually occupied by workers, even where process heat is not a problem. Why then cool all of it?

Plenty of clean, cold drinking water should be made available to the workers. Next on my list would be a way to exhaust the heat and humidity of both machines and workers. Some strategically placed sheet aluminum mounted on or near the machines can reflect the radiant energy away from the workers.

I disagree on the cold water, warm drinks are better. Drinking cold water is analogous to holding an ice cube near the thermostat in your apartment, it shuts off the cooling system.

There is a reason that people, indigenous to hot climates, eat food that is hot in both temperature and spice.

Because Lucas makes refrigerators too?

Boy! I have to disagree on that one!

The spicy food, I believe, originated to cover up the flavors and odors of spoiled food, since food spoils so much faster in hot climates without refrigeration.

It does not make thermodynamic sense to add heat to an already overheated body!

I'll take the cold water any hot day, and I'll take very mildly spiced food every day!

I agree with you.

I worked outside in Arizona for 5 years. Sometimes when the air temperature was 110°F and I was looking at at least 120°F on the pavement. I drove a golf cart on city streets.

The prospect of drinking warm water was not pleasant and I avoided it whenever I could. Cold water for me, thank you.

Food, I like Mexican food and ate/eat it often. I don't care for extra spicy foods, but I like my food hot.

I tried wet collar wraps and misters and found both to not be worth the bother. I did this when I was 55-60 years old.

I survived, with a new respect for first responders and people who MUST work outside no matter what.

Only the body can produce its own heat! Thermodynamically it would be best to drink lukewarm (almost like body temperature) water as this would not add energy nor would it act like ice at the thermostat to make the body produce more heat.

Cold water from the outside is a whole different story.

For the spice I agree it was added for disinfection and flavour.

I'd take the spiced food any day!

Good luck with trying to persuade a British worker to stop drinking tea, whatever the temperature is.

An older friend of mine worked as a welder in Saudi Arabia, building the first Saudi oil pipeline infrastructures. Double welds in the pipes, one inside, one outside. The younger welders worked, guess…inside. I asked how long they could do this at a shift….With leather chaps , gloves , helmets, goggles, etc, and ground temps in the 120's at a minimum, he said there time was limited to 20 minutes , inside. Then off to a tent to drink what the Saudis drink, WARM TEA. They layer themselves in clothing when outside, to prevent thermal transfer of sun heat to the skin, and the air spaces between the folds of light cloth transferred air out and around the body. He said it totally transformed how he thought about "staying comfortable" in a desert climate. He did it for 4 years. Changed my viewpoint , also….

I bet the food was spicy too!

All good valid infos.

Though you did not mention as to why the Toureg always have loose "BLACK" outer clothing, its simply because it blocks all wavelengths of light, including UV passing through. So no sunburn.

Hands up all those who have had sunburn while wearing a white (T!) shirt!

Can you see my hand? And while using waterproof sun block, which wasn't!!

I am (still!) Blonde (though the beard is white now!) and very light skinned! Even though it takes me a long time to get a tan, once I have one, I can work in ANY sun with no further problems!!

Also, I am glad to say that I never suffer from pigmentation problems as people who tan quickly eventually do living/working in a tropical sun.....it looks horrible!

"Hands up all those who have had sunburn while wearing a white (T!) shirt!"
Sunburn, in the UK?, stop taunting us.

Actually, some of the worst sunburn I have ever seen was actually in the UK....

Why?

Its simple,the folk are SO unused to having and being out in hot sunny weather, they COMPLETELY forget sunblock when the sun eventually shines......they lie there a disgustingly painful looking pink!!!

I once saw a young, but heavily overweight woman sunbathing topless, with two enormous pink "cushions" on her chest UGH!!!!! In PUBLIC!!!

Also, with a cold east wind and a clear sky, many forget that the cooling wind hides UV burn effects, till its too late.

In the RN, sunburn was on the same page of regulations as shooting yourself in the foot!!! NOT ALLOWED!!

In the RN, sunburn was on the same page of regulations as shooting yourself in the foot!!! NOT ALLOWED!!

Same, same RAN.........self inflicted injury...........and when you have "turn to" and work with a nasty case of sun burn...........not a nice experience.

I had the misfortune to have to do that ONCE.........I never did it again.

Luckily for me (am I REALLY saying this!!) I knew about sunburn before I joined! You could call me lucky, I think!!

DUUUHHHHH!!!!!!

But I really did....I always had sunblock around...

But you ignore the main point. Your body has a heating and cooling system. Somewhere in there, there is the equivalent of a thermostat. When you sink a cold one down by this thermostat, you tell it that it is "cool out there baby", so it switches off its own cooling system, thus allowing the body temperature to rise until the body realizes it was tricked.

No, you are ignoring the main point that this is not a marginally overheating scenario.

"Somewhere in there, there is the equivalent of a thermostat."

Clearly, there is at least one somewhere. And every thermostat has at least one sensor. The human body's thermostat(s) has(have) many sensors. Many (probably most) of those sensors are in the skin. It is not unusual (for me at least) to have one portion of the body overly warm while another part of the body is overly cool. In my case the most common occurrence is to have cold feet while my torso is overly warm, either while sitting or lying down. To me, this indicates that there are multiple thermostats in the body.

I'm definitely NOT a physiologist, but I doubt if the body pays much attention to the temperature of the contents of the stomach. Whatever is put there will soon acquire the temperature of its surroundings. If it is hot, it will loose most of that heat to the surrounding tissues, making them slightly warmer. If it is cold it will absorb heat from the surrounding tissues, making them slightly cooler. Since the stomach's volume is a small fraction of that of the torso, anything put there can make only small changes to the temperature of the torso.

Evaporation of water is the normal mode of cooling for the body when normal radiation is inadequate, and circulation of air past the body facilitates that evaporation. That evaporated water and some of the electrolytes that get carried out with it must be replaced. I choose to get my water replaced in the coolest drinkable form, either with or without included electrolytes.

Which in a really hot climate would be not the most efficient way of keeping cool!

See this post.

You have to cool down your core temperature...... you can't do it with warm drinks.

There is some dispute on how cool or cold the water should be but never warm. The colder the water the longer it takes for it to hydrate the body. The stomach is though very capable with may blood vessel to help cool the body with cool or cold water. Just as it does in the winter with hot drinks to warm one's self.

As far as the food that is heavily spiced. The spices were used as a preservatives. Many of those spices deter bacterial growth. They also cover up the taste of the food as it may have been a little rancid before spices where used to help preserve it. As meat was serve fresh from the kill for a couple days before being preserved.

People today eat heavily spice food because it's an acquired taste.

I have negated your single off topic.....

My Mother drank hot tea to cool. Me too nowadays, it works well...

You have been proved correct by better scientists than I will ever be. (Not that I am any sort of scientist you understand!)

Also, you can eat meat that is "on-the-turn" so to say.....

These articles appear to be of the same study.
http://www.npr.org/blogs/thesalt/2012/07/11/156378713/cool-down-with-a-hot-drink-its-not-as-crazy-as-you-think
http://www.smithsonianmag.com/science-nature/a-hot-drink-on-a-hot-day-can-cool-you-down-1338875/?no-ist
I agree that spices were used in Europe to hide the taste of old meat year round but Indians use them with vegetarian meals that don't need disguise.

Thanks for the links!

From the second link (my addition of boldface):

"If you drink a hot drink, it does result in a lower amount of heat stored inside your body, provided the additional sweat that's produced when you drink the hot drink can evaporate,...".

Although I've been doing quite a lot of sweating the last few days (doing hard work outside when it's been just under 100°F, 101° today), I absolutely abhor sweating. I've been drinking LOTS of cold water, and am not going to do anything to increase the amount of sweat.

I think this drinking a hot beverage to cool down illustrates a couple of things.

1. The power of positive thinking. If you think it will help, it will.

2. In order to drink the hot drink, you have to stop whatever else you were doing. If that means stopping work for a while, your muscles will stop creating as much heat, so of course you cool down.

But this is a "i dont like it" problem.

Going back to the OP we would have to say give them workers hot drinks and let them sweat! Also give them breaks often enough.

If you dislike it does not mean it should not be done!

I personally have noticed that when I am drinking hot coffee in the morning when it's hot, I feel hot and sweat a lot. Once I switch to cold water, I feel beetter. I like cold water better, so will drink it more anyway.

When I worked at the shipyard, way back when,?.. we had tried cooling/warming hoods with vortex tubes for the finishers, but at the time, these were hard to regulate. So they were scraped and are doing pretty much what we do at the company where we are now where depending on the weather either bundle up or drink plenty of fluids.

The fluids (which is cold) does two things, rehydrate you and cools your core temperature.

Where I am not, where the workers work near equipment where it's in excess of 100°F and pull 12 hour shifts. They are also compensated well.

Hydration, acclimation and moderation are about all you can do.

Machine operators should have cooling fans at their stations and maybe misters if feasible. (mostly not unless you're outside)

In industrial settings removing the hot air means it has to be replaced with other air, but chances are $ determine how cool the workers are.

Wet scarves don't work, even in Arizona. Misters just make you wet. If there were a good, cheap way to do it somebody would be selling it.

They roof houses here when it's 110°F.

I am one of those employees that works on and near some very hot processing equipment and steam, Yes I know that A/C and environment suits are expensive but have you considered how expensive it would be to pay restitution to the family of someone that has perished due to heat related issues. Why are cooling suits NOT realistic for teams??. We do get used to the heat to a certain degree but the human body can only tolerate so much before it shuts down. We (those of us who choose to work in these environments) have devised ways to tolerate heat by revolving the point person and frequent breaks, COLD WATER, neck wraps, fans (but as far as I'm concerned the fans do little unless they are drawing from somewhat cooler air which usually doesn't happen), cooling areas away from the heat source, and loose fitting clothing with a wicking underliner of some kind. My biggest suggestion is to revolve teams in tolerable intervals to a cooler work environment.

(Ok off my soapbox, please resume)

Here's an idea: rotate your teams with Mahogany Row and see just how fast you get those cooling suits.

Yeah I always wondered what the carpetland people would think about while putting up with the environment I work in. Kinda puts a smile on my face.

They wouldn't put up with it.

I wonder how OP feels about class action lawsuits after folks start falling out in his plant? Better get over the cost now, while he still has a business.

these help and keep air moving

My wife bought these for me.

They are a joke.

Right! My friend and employer gave me one too. I tried it two or three times, several years ago. A fan is much more effective.

"I am Galt, Master Thrall of the planet Triskelion. I have been sent to welcome you."

Pls describe building.

One of the most effective cooling solutions is reflective insulation under the roof. Can reflect up to 97% of incoming solar.

Unless, of course, you have it already. Best done with new buildings. But still very effective for retrofit.

Earlier poster described 'Aluminium panels' - best to use something like sisalation. https://www.google.com/?gws_rd=ssl#q=sisalation+paper&safe=off

Sisalation will reflect, but have almost zero 'heat mass', unlike aluminium.

About all you can do is provide fans to move the air,and shields to reflect some of the heat.

Provide Gator aid(Not an endorsement) or other electrolyte drink to employees free of charge and advise them to drink when needed.

Large coolers of this can be mixed up rather cheaply.Dehydration can lower productivity, affect quality,and be injurious to employees health.

If they can stay hydrated,their bodies will adapt, unless of course,it is extremely hot beyond human tolerance.

That's the most common-sense, real-world, economical and physiologically correct response I've seen.

Look at (outdoor) athletes, farm/road laborers and the military for the best guidance. Wildland fire fighters work their asses off in middle of Summer, all day. No cool showers at night for them, either.

Soldiers patrol the desert, outside their vehicles (which aren't always air conditioned) for hours.

Bike racers, endurance runners and soccer players work hard for hours at a time. I did 40 miles on my new road bike last weekend in nearly 100F heat. I'm used to it, and had plenty of cold/cool water. (I'm not a racer, I did it cuz it's fun.)

You need:

• Enough clothing (and/or sunscreen) to keep the sun off your skin
• Moving air to allow your sweat to evaporate
• COLD fluids to help your core stay cool
• Water/electrolytes to replace your sweat.
• Allow acclimation, breaks as needed and lower effort levels.

You have this problem in Massachusetts! Be glad you're that far north!

You did not make clear whether the hot environment was simply due to the weather, or was due to heat-emitting processes/machinery.

When I have to work in the non-air-conditioned sections of our plant near San Diego, I find that air movement is really important. If there is no ceiling fan where I have to work, then I move a pedestal fan to blow on me, and that helps a lot.

If it is heat due to processes/machinery, then appropriate shielding/isolating and proper exhaust is paramount.

In our factory this worked well but you need the following: Plenty of free water although the quality is not important. Our factory had a pitched galvanized tin roof with gutters and downpipes. A swimming pool pump pumped water to the roof and it is dispersed with garden sprinklers over the roof. The run down water is collected in the gutters. The downpipes feed the water back to a tank from where the pump collects its water. Significant drop in temperature was observed even with the big NC machines working on full tilt.

I appreciate that will be effective, but with respect Lewis, it will not approach the performance of reflective ins. - ideally a double layer of double sided sisalation, with joints sealed / taped.

An air space between the two layers increases the performance marginally - its chief purpose is to prevent dust build up on the lower layer over time, which could reduce reflectivity.

Been using it since the '70s.Never disappointed! Get yourself an IR thermometer, measure the inside temp of the roof at full sun.

Not so good if the heat comes from the equipment inside the factory.

Patently obvious -

A quick to apply and relatively cost effective and proven solution would be to copy the way courtyards are cooled in hot countries, by the introduction of water and fountains. As the water evaporates it absorbs heat, cooling the surrounding air. A visit to the Alhambra Palace in Spain demonstrates the process admirably with temperatures rarely above 70º in an ambient that peaks at 110º.

Modern misting equipment would make the process more efficient.

If Qatar eventually hosts the world cup, building a canal with misting equipment around the pitches in all the stadiums would cool both players and fans.

Can you keep the heat away from them with Air Knives?:

https://www.exair.com/

Blow the hot air back to the machinery from whence it came and keep it away from the workers.

How about this one?

http://www.vortec.com/images/ProductSlider/PersonalAC/22525%20Use.jpg

You'll have to keep connected to a compressed air line but, hey, it's cool. (",)

regards,

Vulcan

Get neked and glue heat sinks all over your body.

I used to work in a vacuum forming factory in Florida. It was a large industrial building with no AC and no ventilation most of the time. The ovens were open and too much air movement interfered with the heat distribution inside the ovens. In the summer, we commonly have temps and humidity in the 90s.

1. Make the workspace clothing optional. A good canvas work apron is all you need.

2. Encourage more comfortable clothing. Kilts are amazingly comfortable once you get over that silly macho thing about wearing a skirt! Loose button up shirts are more comfortable than a T-shirt, that sticks tightly to your body and seals up at the neck and arms. I have a homemade thing I call the "utilisarong" that is a 4 ft wide piece of canvas dropcloth, wrapped around my waist with a utility belt holding it in place. It is folded over at the waist and in front so I have 6 to 8 layers of heavy canvas over my, um, crotch. I wear it to do yard work and construction. The neighbors have gotten used to it as long as I'm careful when working on the roof.

3. Swamp coolers rock, but only in arid climates. (Come to Burning Man and ask about staying cool in the desert.)

4. Move the air. Ceiling fans blow air down, as long as the air at the ceiling is not hot. Pedestal fans if it is.

5. Wear a battery powered fan hat. I have an old one that is a pith helmet shaped thing with a fan in front pointing down at my forehead. It has a solar panel on top, but the battery pack works better. It is rigid with an adjustable headband. The design keeps it suspended above the head so it doesn't restrict air movement. Mine is over 20 years old. http://www.coolest-gadgets.com/20060319/solar-powered-fan-hat/

"Make the workspace clothing optional. A good canvas work apron is all you need."

I'll suggest that one to the ladies.

I suspect most business won't allow the clothing optional solution.

The OP posted here on the engineering forum for a technical solution to the problem. Social issues should be addressed elsewhere.

Several years age(5,10,? time flies!)I read about gloves that were cooled,and sealed around the wrist,and a vacuum applied while chilled water circulated through them.

They could increase an athlete's work out time (more than double) by a large percentage by keeping the whole body cooler.

Seems fatigue and the accumulation of Lactic Acid in the muscles is closely tied to muscle heat.

The hand has many arteries and veins,but they tend to close up when cold.

The vacuum prevented the normal contraction of the blood vessels when exposed to cold temperatures,and kept the blood flow going while the water cooled the blood.

http://gizmodo.com/5939295/stanford-is-building-a-body-cooling-glove-that-might-work-better-than-steroids-for-athletes

This was developed primarily for athletes,but I am sure it will have practical uses in very hot work environments when it is miniaturized.

Glad to see someone in management or supervision that cares about the plight of the working class.

Water and vacuum lines to an athlete on a treadmill may produce wonderful results and interesting scientific physiology data. Those gloves look like they make a hand useless, a bad attribute for most workers.

The referenced article is over 2 years old now.

I remember reading somewhere that the unit has been reduced to a portable size for mobile training athletes, like runners.

Don't know the cost.

I will try to find the link about that and get back here with it.

I think that the only efficient way to cool down the workers is to cool down their working environment. If it's not possible to cool the whole facility with a large air-conditioning system, then you could install such smaller systems locally (in the hottest areas of the facility). It should be much better if you could transfer the heat of the process equipment outside the building in a more "direct way" (e.g. pipes with circulating, cold water attached to the hot spots of the equipment could tranfer the heat outside the building). Always the better way is to "heal" the cause of a problem and not the result.

Since the machines are throwing off heat - you need to manage that heat by providing thermal barriers - Aluminum panels help reflect the heat. Channel hot, humid air away from workers, consider using a dehumidification system to (1) recover useful water for fog cooling areas where it is exceptionally hot, and not over 50% humidity, and (2) reduce the apparent heat index the workers experience, thus allowing perspiration to evaporate more readily. If this is a situation where PPE workers are using is an impedance to heat transfer, consider better protective apparel.

If you have a source of waste heat available that is sufficiently high temperature (at least 150 °C, consider installing an ammonia absorption chiller, but this only needs to be enough to chill down outside exchange air and dehumidify.

We are experiencing a cold front in West Texas today, and it feels like fall here, on July 31.

Perhaps this might do

http://www.vortec.com/c-30-personal-air-conditioners.aspx

I would suggest plenty of fluids and frequent air replacement.

You actually get used to working in relatively high temperatures and you gradually stop sweating as the body simply stops producing quite so much heat.

When I got back to the UK in April after 2.5 years in Singapore (with no air conditioning except for a ceiling fan or three), it took me 3 winters before I could handle a British winter.....I froze my "whatsits" off!!! The summers in Europe weren't (still aren't!) hot enough!!

I like it to be around 40°C......On holiday in Turkey some years ago on a Yacht with no A/C, I loved the 50°C by 11 am.....my wife was not so keen!!

There is no question that different people have different body chemistry and metabolism. There is also no question that one can, at least to some degree, become accustomed to different climates. It has now been very nearly 50 years since I spent some time in the tropics (Puerto Rico). I learned very quickly that I'm NOT a tropics guy. As far as I'm concerned, if you don't need a sweater in the morning, then it's too hot.

As a teenager, I spent one summer working outdoors in the Sacramento Valley, in areas where the temperature reached 45°C. The next summer I got a job washing dishes for $10 a week, plus room (tent) and board at a YMCA camp at an altitude of 6500 feet. I've never regretted that decision.

I have been working outside for the last several days in temperatures approaching 40°C, and hate it. At least its all in the shade. ...but I started this task, and must finish it! I do have, and make good use of, my A/C, which fortunately is still working well 44 years after it was installed!

I can't imagine working, or even just relaxing, at 50° for more than a few minutes.

I would guess that its also at state of mind AND body to accept high temperatures and high humidity. Though I haven't really thought about it in depth.

If I remember correctly, this took generally about 3 weeks.

After that, it was not a problem.....

Its not as though I only went there once, I actually was in the far east 3 times for long periods (greater than a few months!) and several shorter visits as well....

A few years ago I was on holiday in Turkey during a hot period with day temps to 55°C, similar to Singapore. I did not see a humidity meter in Turkey, though Singapore is easy to remember, 100% most of the time with occasional dry days down to 85-90%......

The body adapts and produces less heat the longer you live there, BUT, you still sweat off most of the calories you eat, I was as thin as a rake after each visit....even eating well.....any fatties here? Go to a hot, really hot climate and live....

"A few years ago I was on holiday in Turkey during a hot period with day temps to 55°C, similar to Singapore."

Wikipedia "Singapore is an island south of Malaysia surrounded by some smaller islands as ... The highest recorded temperature is 36.0 °C (96.8 °F) on 26 March 1998."

Looks like the heat got to you, Andy. Nevvermine, does to me too. ;-)

I can only go by the Guy charged with recording the weather on board the aircraft carrier when parked across from the Naval Dockyard.......maybe he made a mistake, or my memory, its a long time ago now, but that was technically Singapore Island, not Singapore town!!

You know the reasons behind the address of New York, New York? So good they named it twice!!!

Its the same for Singapore, Singapore.....

We could fry eggs in 2 minutes on the flight deck, though I declined eating one....

Also, since when has temperature been accurately recorded in Singapore, did you find out from your source, 1998 is not that long ago....?

Come on! You are remembering the temperature in the engine room!

No seriously, I am remembering the daily newsletter that detailed both actual weather and expected....we had no TV, only a single UK radio program, I forget which....it was the only way to get local news.....

Sadly I have no copies anymore....

Maybe big lumps of steel get warmer than the surrounding countryside....and affect the temps read....

Its many years ago now.....

You might contact some Chinese clothing manufactures, they seem to have a secret to keep their work force going for extended periods of time, regardless of the temperature. I'm not sure where their thermostats are located, but you could ask them during your consultation.

It's all the AK-47's pointed at them that keep them going in the heat! Don't fool yourself, fear is an exceptional motivator. Hey this is a joke, people. I don't want the Chinese army coming knocking on my front door for "dissing" them.

Change environmental factors if possible or get a cooling suit like this one:

This is basically the core of the extravehicular mobility unit astronauts use when out in space. No budget: have silicone tubes sewed to appropriate underwear. You don´t need to connect it to a fancy cooling unit: try circulating tap-water

The problem is that when the humidity rises past the saturation point evaporation type cooling systems cannot effectively work.

I am sure that dehumidification of the air and/or proper air movement would be the best low-cost solution for large work areas.

Often just providing active large scale air movement wherein the cooler air at ground level is pulled into the building and then the air is effectinely circulated within and thoughout all the stagnent building areas then finally exhausted at the higher elevations of the building after it has absorbed all of the heat load possible makes the environment acceptable and safe.

It is possible to use reverse-biased diode cooling systems to drop the air temperature 10-20 degrees below ambient rather efficiently but I do not know if any manufactures have pursued this technology on a large scale basis.

The problem is that when the humidity rises past the saturation point evaporation type cooling systems cannot effectively work.
This i know, we tried (against my direction) and installed a swamp cooler for the burn bed here in Texas. All it did was make everything damp.

Peltier junction devices are not very efficient. Their only advantage is that the are quiet and have no moving parts, aside from the circulation fans that are required for both sides.

As a volunteer firefighter I prefer a cold or up to warm cloth on the back of my neck and some of the same to pour on my head. This cools the most important and sensitive part of my body, the head. Those turn-out gear are intended to handle over 300^oF for several minutes so you can imagine how hot they get. It is like wearing a snow suit in July. For this reason I open my coat to cool my body and conserve energy as much as possible. If it gets extremely hot the cold water is used on all body parts. We have a hand shower that is connected to one of the pumpers outlets to make these things easier.

The primary cooling method is to drink plenty of ice cold water to replace body fluids. I like it the water cold so that means I drink more of it.

Years ago I was in a Haz Mat level A suit on an extremely hot day (well over 90^oF). Under the suit I wore only underpants and an SCBA pack. During the 15 minute entry I lost over 12 pounds of water, all of it went in the boots. The other younger entrant had to be taken to a hospital!

Good Luck, Old Salt