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How Hot Is Too Hot? A recent study.

Paintboy2

Active Member
Time of past OR future Camino
2021
I came across this study today and it caught my eye because of the recent heatwave in Spain. I suffered my own heat event in Italy 3 years ago and it is memorable in the speed that it took hold of me. I'm starting the Norte in a week and I'll be evaluating temps AND humidity along the way.
 
A selection of Camino Jewellery
An interesting article & timely reminder not to push things too far...even if we feel we're coping okay.

I had my own experience on the Milford Track, south island of New Zealand; not a place you'd normally associate with heat stroke...well, I didn't anyway...
It wasn't a particularly hot day (by Aussie standards) but involved a climb. I got into trouble because I was dressed to protect myself from those 'most mischievous of creatures' (Capt James Cook), the plague proportion sandflies, rather than the temperature (unseasonally high).
I began feeling very unwell & couldn't work out why. Fortunately I had seen a doco just a few months earlier (Levison Wood's 'Walking the Nile') where a person died from heatstroke. For some reason I recalled that, recognised the symptoms in myself & acted immediately.
I'm not going to lie...I got a big fright, especially thinking of what may have happened if I'd ignored the warning signs & just kept going....
Don't underestimate the effects of heat exposure.
👣 🌏
 
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I'm not going to lie...I got a big fright, especially thinking of what may have happened if I'd ignored the warning signs & just kept going....
One of the scary aspects is that your thinking is likely to be impaired and leave you more exposed to the dangers. Applies at the other end of the spectrum with hypothermia too. I've had a narrow miss with that when I became very sleepy on a mountain pass in snow and found myself thinking that forty winks in that handy snow bank would be a good move. Fortunately a tiny voice deep in my mind persuaded me otherwise.
 
I think it's helpful, in the cool of the morning before setting out with our daily cases of "get-there-itis", to plan alternative stopping / resting / hauling-out points for the day's route. Because as the previous posters have said, the heat injury creeps up on us and affects our thinking (ie, brain functioning) before we're aware of it.

And be ready to abort the trip if necessary; I got caught in a heat wave on the Geneva route in Sept 2018 and had to bail out.
 
One of the scary aspects is that your thinking is likely to be impaired and leave you more exposed to the dangers. Applies at the other end of the spectrum with hypothermia too. I've had a narrow miss with that when I became very sleepy on a mountain pass in snow and found myself thinking that forty winks in that handy snow bank would be a good move. Fortunately a tiny voice deep in my mind persuaded me otherwise.
Yes!!!...couldn't agree more. I was aware something was wrong physically & also noticed my brain feeling hazy. It took all my concentration to figure it out & still to this day, I don't know how I made the connection to the doco.
Thankfully both of us had that tiny voice & are here to tell our tales.
👣 🌏
 
A selection of Camino Jewellery
I came across this study today and it caught my eye because of the recent heatwave in Spain. I suffered my own heat event in Italy 3 years ago and it is memorable in the speed that it took hold of me. I'm starting the Norte in a week and I'll be evaluating temps AND humidity along the way.
Hi I can’t open while on WiFi in Spain. What are the main points?
 
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I came across this study today and it caught my eye because of the recent heatwave in Spain. I suffered my own heat event in Italy 3 years ago and it is memorable in the speed that it took hold of me. I'm starting the Norte in a week and I'll be evaluating temps AND humidity along the way.
Unfortunately, I get the message that the article is not available in my country (UK). is there another way of accessing it?
 
All of this is subjective as heat / humidity effects each individual in a non-linear way. ie, some have greater tolerance than others. However, as you have had a previous experience, it may be wise to take greater care, raising concern for susceptibility.
 
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I live in Texas and it has been at least 38 C or above for about 2 weeks now with recent temps getting to 40 or 41 C with a "feels like" temp of 43 C some days. All of this with around 50% humidity. It is impossible to do anything outside. I say this as someone who has lived here my entire life and is very used to high humidity and high heat. This has been unbearable. Stay safe out there.
 
Be careful! Once you've had one heat injury it can make you more susceptible to future ones!
In my own experience, I've found that it's more a case of after a first heat attack, realising that the susceptibility to them is there.

After that, the older you are, the greater the risk.
 
Be careful! Once you've had one heat injury it can make you more susceptible to future ones! Hope you'll walk early and stop when it gets too hot no matter the time or distance!

for Spain one July some years ago it was a case of "half past four, boots on the floor" ! I made sure I only walked to approx. ten or half past for my days destination.

The bonus was, I love the pre-dawn dark anyway :) There are still stars in the sky and the night is slowly changing from black to that gorgeous deep dark blue. Hydrate and rest. Walk soft. stay safe. Buen Camino!

Samarkand.
Hi I can’t open while on WiFi in Spain. What are the main points?
 
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I came across this study today and it caught my eye because of the recent heatwave in Spain. I suffered my own heat event in Italy 3 years ago and it is memorable in the speed that it took hold of me. I'm starting the Norte in a week and I'll be evaluating temps AND humidity along the way.
I believe the general 'rule of thumb' is that it is medically Dangerous to be outside when the 'temperature' is above 35C. Remember that the temperatures quoted by the meteorological people are for thermometers located in the shade approx 1 metre above the ground in a special 'box'. In the full glare of the sun it's gonna so much more than that.
 
For those unable to access the article this graph summarises the results of their controlled experiment to define a “critical environmental limit” for young, healthy subjects. Below that limit, the body is able to maintain a relatively stable core temperature over time. Above that limit, core temperatureants began to rise - in other words the point at which their body cooling system could not cope. It is important to recognise that the participants were incolved in minimal activity similar to "cooking and eating". Throw into the mix normal camino activity and the results are very scary.
We in Australia are accustomed to high summer temperatures - we had one daily maximum in my hometown of 47c last summer, and 40c+ is not at all unusual. But our humidities on such days are very low indeed.
file-20220624-14-jt7lbq.png.jpeg The yellow zone "represents the average critical environmental limit for young men and women at minimal activity"
 
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I live in Texas and it has been at least 38 C or above for about 2 weeks now with recent temps getting to 40 or 41 C with a "feels like" temp of 43 C some days. All of this with around 50% humidity. It is impossible to do anything outside. I say this as someone who has lived here my entire life and is very used to high humidity and high heat. This has been unbearable. Stay safe out there.
I'm up in the North East Piney Woods of Texas and have been experiencing the temperatures you're talking about. I have been working outside in this and while it is "warm" the biggest thing for me is take it slow and stay hydrated. I'm 62 and in fairly good condition but each person is different. The studies I have seen suggest that to fully acclimate to a new environment it takes two weeks sadly this is not an option if someone is walking right into the mouth of the lion.
 
Hi I can’t open while on WiFi in Spain. What are the main points?
88°f and 100% humidity will make sweating ineffective at cooling the skin, leading to heat exhaustion and possibly heat stroke. Temps over 88°f have a lower humidity threshold, for instance, 100°f at 60% humidity. Bottom line, be careful, hydrate, seek shade, live to finish the journey.
 
Technical backpack for day trips with backpack cover and internal compartment for the hydration bladder. Ideal daypack for excursions where we need a medium capacity backpack. The back with Air Flow System creates large air channels that will keep our back as cool as possible.

€83,-
For those unable to access the article this graph summarises the results of their controlled experiment to define a “critical environmental limit” for young, healthy subjects. Below that limit, the body is able to maintain a relatively stable core temperature over time. Above that limit, core temperatureants began to rise - in other words the point at which their body cooling system could not cope. It is important to recognise that the participants were incolved in minimal activity similar to "cooking and eating". Throw into the mix normal camino activity and the results are very scary.
We in Australia are accustomed to high summer temperatures - we had one daily maximum in my hometown of 47c last summer, and 40c+ is not at all unusual. But our humidities on such days are very low indeed.
View attachment 129414 The yellow zone "represents the average critical environmental limit for young men and women at minimal activity"
Thanks for the summary. You beat me to it.
 
All of this is subjective as heat / humidity effects each individual in a non-linear way. ie, some have greater tolerance than others. However, as you have had a previous experience, it may be wise to take greater care, raising concern for susceptibility.
@MichelleElynHogan, were you responding to a particular post here, or making a more general comment about the study itself? I ask, because my reading of the article is that there were objective measures developed and used to test individuals' heat stress response. My view is that measuring the point at which an individual's internal temperature started to rise would have eliminated any subjectivity on when they were unable to 'maintain a relatively stable core temperature over time'.

There are several considerations that might create some uncertainty about what is dangerous, such as the study being conducted on young fit individuals undertaking what might be seen as relatively undemanding activities indoors, compared to walking outside, potentially without shade, which is what most of us do on the Camino. I would suggest all of these things indicate one should be even more conservative about assessing when it becomes dangerous to walk.

On this, the US National Weather Service suggests that Heat Index values can increase by as much as 15F (~10C) where the activity is conducted outside without shade - conditions that most of us face walking on the Camino.

All this goes to the conclusion that across much of northern Spain over the next few days, the maximum daily heat indices will be above the point that can lead to dangerous heat disorders with prolonged exposure and/or physical activity in the heat.

It would be unfortunate if someone reading your post were to take it that they could rely on some subjective view of their own heat tolerance to keep walking in such conditions, rather than avoiding walking, or planning to take a break during the worst heat of the day.
 
@MichelleElynHogan, were you responding to a particular post here, or making a more general comment about the study itself? I ask, because my reading of the article is that there were objective measures developed and used to test individuals' heat stress response. My view is that measuring the point at which an individual's internal temperature started to rise would have eliminated any subjectivity on when they were unable to 'maintain a relatively stable core temperature over time'.

There are several considerations that might create some uncertainty about what is dangerous, such as the study being conducted on young fit individuals undertaking what might be seen as relatively undemanding activities indoors, compared to walking outside, potentially without shade, which is what most of us do on the Camino. I would suggest all of these things indicate one should be even more conservative about assessing when it becomes dangerous to walk.

On this, the US National Weather Service suggests that Heat Index values can increase by as much as 15F (~10C) where the activity is conducted outside without shade - conditions that most of us face walking on the Camino.

All this goes to the conclusion that across much of northern Spain over the next few days, the maximum daily heat indices will be above the point that can lead to dangerous heat disorders with prolonged exposure and/or physical activity in the heat.

It would be unfortunate if someone reading your post were to take it that they could rely on some subjective view of their own heat tolerance to keep walking in such conditions, rather than avoiding walking, or planning to take a break during the worst heat of the day.
The study itself expressed that this "represents the average critical environmental limit for young men and women." A person can therefore conclude that an "average" would include variations from one person to the next. My conclusion is that each person can be at a different level and the limit can be higher or lower but be safe and don't bet your life on your limit being higher.
 
Technical backpack for day trips with backpack cover and internal compartment for the hydration bladder. Ideal daypack for excursions where we need a medium capacity backpack. The back with Air Flow System creates large air channels that will keep our back as cool as possible.

€83,-
Weather is forecast to be 107 F/41.7 C in Zaragoza where we will be today. Unless we can find a cool church or palace. I think our sightseeing will be limited to the inside of an apartment! To Canfran tomorrow. Hope it will be cooler in the mountains.
 
I believe the general 'rule of thumb' is that it is medically Dangerous to be outside when the 'temperature' is above 35C. Remember that the temperatures quoted by the meteorological people are for thermometers located in the shade approx 1 metre above the ground in a special 'box'. In the full glare of the sun it's gonna so much more than that.
Wow. I'll just go inside now then. Instead of finishing my second beer and cycling home.
 
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Temperatures are at about 30 this week in Calgary and I do not like heat. Fortunately, it was a little cooler yesterday, when I walked some distance and was forced to walk home from downtown in the afternoon, as the train which I boarded was on the wrong route, according to its marking. But I have the good fortune to live in a basement apartment and the heat is still going down at night. I shall be walking my caminos in France and Spain beginning in September on the Aubrac plateau at Le Puy. I anticipate that temperatures will gradually be decreasing as I walk slowly south into the autumn and lower altitudes. I would not wish to be in Spain at present.
 
The focus is on reducing the risk of failure through being well prepared. 2nd ed.
60% to 100% humidity is very high, though I do know that those sorts of % can be common in New England and elsewhere in the USA.

And I would NOT want to be out and about in 100% humidity at 30°C+ !!

It is certainly interesting to have gradated the previous rule of thumb 35°C advice in relation to the humidity level, though of course that goes both ways, above and below that temp.

In my experience though, it's rare on any Camino for 30°C to be uncomfortable, though having said that, right now here in Portugal these days, it does seem to be a bit of a cut off point for me personally. 39°C outside right now though ...
 

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