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Summer Health and Safety

Submitted by An Outdoor Idiots Team Member.

Last winter, we published an article on how to survive the cold weather. We scoured medical texts and real stories, and plundered every resource to bring you an account of all the wonderful things that can go wrong with your body in cold environments. We presented our findings in our critically acclaimed guide to winter health and safety.

Many people probably died as a result of taking our word for it. But that's okay. We knew the risks.

Well now it's August, traditionally the hottest month in the UK. And we are at it again. We now present to you our very own guide to surviving anything any summer will ever throw at you, ever. Possibly. Except for midges. And lightning. If you have been told there is a cure for either of those things, you have probably been lied to.

For a slightly more personal and possibly more useful account of trying to survive summer, you could also try this.

He STILL smokes a pipe, so you should STILL heed his words.

The principal hazards for the outdoor enthusiast in hot weather are UV exposure, dehydration, hyponatremia and heat exhaustion. Heat exhaustion, if unchecked, can lead to heat stroke. Each of these problems will now be covered:

UV Exposure

Effect of Over-Exposure to UV Light

Exposure to Ultraviolet (UV) light from the sun can adversely affect both the skin and the eyes. It doesn't help to delve too deeply in to this subject - it gets too confusing, particularly in the case of the affects on skin. For example, it is widely believed that UV light (UVB in particular) can cause skin cancer. However, it is also widely believed that insufficient exposure to UV light results in a deficiency of vitamin D, which can increase the risk of other forms of cancer. In the long term, balance, i.e. moderate exposure to sunlight, seems to be the key. But, for the purposes of getting through a hot day in the wilderness, forget about all that. We want to block the sun as much as possible, so that our eyes don't hurt and we don't get sunburn.

Prevention of Over-Exposure to UV Light

Sunglasses can be used to protect the eyes.
A wide-brimmed hat can be used to protect the eyes. It can also protect the face and neck, particularly during the middle of the day when the sun is high.
"Sunscreen," "Suntan Lotion," "Sunblock" etc can be used to protect the skin. The higher the "SPF" (sun protection factor) of the lotion, the better the protection, in theory. E.g. an SPF rating of 15 means that, if you apply the lotion, it should enable you to get away with exposing your skin to the sun for 15 times longer than you normally can before it starts to burn. In practice, though, it is often recommended to get a sunblock with an SPF of 30 (anything rated over that probably won't actually offer additional benefit), and re-apply it regularly throughout the day. If you are going to be swimming or sweating, some lotions claim to be good at not getting washed away.
A lot of clothing is now available which is designed especially for hot weather and protection against UV light. Often such clothing has an SPF rating, just like sunblock lotion. Most ordinary clothing will offer some protection, but it is nice to be able to get specially made, light and airy clothing with a known SPF.
All else being equal (the level of cloud cover, namely), the hours between 11am and 3pm are when the sun's rays are the strongest. On particularly bad, cloudless days, therefore, it might be wise to find shade during those hours.

Dehydration

It is much easier to become dehydrated when the weather is hot and you are exercising. The body has to deal with the high air temperature, the radiated heat from the sun, and the heat that the body itself generates when you exercise. If the core temperature of the body is raised much above its normal 37°C (98.6°F), then it is in serious trouble. So it has an ingenious emergency cooling mechanism, called sweating. Brilliantly, when the skin temperature, normally a few degrees cooler than the core temperature, reaches approximately the core temperature, the body starts to produce water (and other stuff - sometimes salty, sometimes fatty, depending whereabouts on the body it is produced) at the surface of the skin. This might seem a bit pointless as a cooling mechanism - after all, the water will be at the same temperature as the body that produced it. However, the water is now sitting at the boundary between the skin and the air, and the magical process of evaporation occurs. Heat from the body is taken on by the water, and that heat is used up in allowing water molecules to break free and escape into the air (evaporation). In this way, the body is normally able to shed excess heat and maintain a healthy temperature.

This is all very good, but all the lost water will need to be replaced. If it isn't, you become dehydrated. Dehydration ultimately means that blood volume and blood pressure become reduced (as the blood becomes thicker), and it becomes harder for your heart to move blood around, which is vital, for example, for getting oxygen to your brain. If you become severely dehydrated, you are likely to breathe faster and your heart will pump faster in an attempt to overcome this reduced blood volume. Your body can also get even hotter as it becomes less able to produce sweat.

Avoiding Dehydration

I'm not going to quote a lot of the commonly quoted figures about how much water we should normally drink per day, and how much more we need to drink in hot weather or during exercise. Everybody seems to be very different in terms of their normal daily intake, and everybody seems even more different in terms of how much they sweat at various temperatures or under various levels of activity. What is important, is to recognise that if you are sweating, you will need to drink more water than usual. So, if you are heading out on a hot day, you might try:

Drinking as much water as is comfortable before you set off.
Carrying much more water than usual.
Taking every opportunity to collect more water throughout the day.
Slowing your movement, to reduce the amount you sweat.
Avoiding diuretic drinks such as alcohol and tea, coffee or any other drinks that contain caffeine.

There are some signs that will help you know if you aren't drinking enough: Thirst, dry lips, dark urine, dizziness, headache, rapid breathing, even tiredness. However, water isn't the only thing that you lose when you sweat, which is why you have to watch out for...

Hyponatremia

Hyponatremia refers to a deficiency of salt in the bloodstream. When you sweat, you lose salt as well as water. Your body needs a certain level of salt, where it acts as an electrolyte in the bloodstream. If you simply drink water to compensate for sweating, it is quite possible, during the course of a day, or even a few hours, to become seriously ill. Indeed, as a worst case, if your salt level becomes very low and you then drink a huge amount of water, this can lead to "water intoxication", whereby the cells in the brain and central nervous system become flooded with water and are damaged. The least that might happen is that you become confused and / or collapse, and it is also quite possible to die within a matter of hours. So:

Avoiding Hyponatremia

Try to ensure that you eat well in the days leading up to the event that is likely to cause heavy sweating.
Eat salty foods during the periods that you are sweating, as well as drinking water.
Avoid drinking a huge volume of water in one sitting.
Bring isotonic "sports drinks" which are designed to replace, in the correct balance, exactly the kinds of things you lose when you sweat. These are also available in powder form, to be mixed with water, which may be more practical for longer trips where weight is an issue.
It is commonly advised not to take "salt tablets". These are very concentrated, and it is easy to overdo it. This can lead to, you guessed it, hypernatremia, which is every bit as dangerous as hyponatremia. In fact, in many ways, hypernatremia is the same thing as dehydration as far as your body is concerned.

There are some signs that might help you know if you aren't replacing lost salt adequately. However, some of the signs are the same as for dehydration, so diagnosis isn't always straightforward. Signs can include: Tiredness, weakness, cramps, headaches, dizziness, confusion, nausea, bloating.

Heat Exhaustion

The exact definition of "heat exhaustion" is a bit hard to pin down. According to some medical texts, we've already covered it: if you are suffering from dehydration and / or hyponatremia as a result of exercising on a hot day, you are suffering from heat exhaustion.

But it's not necessarily as simple as that. It is important to recognise that you can dangerously overheat, even if you are not dehydrated, are not suffering from hyponatremia, and the weather is not particularly hot. Running up a mountain while wearing a woolly jumper and a balaclava would probably do it for most people. Even sitting perfectly still on a blazing hot day could do it. The core body temperature only needs to be raised by a couple of degrees for it to be in great danger. Beyond this, organs, such as the brain, start to die.

So even if you feel certain you are not dehydrated and are not suffering from hyponatremia, it is a good idea to watch out for any ill effects due to the heat. Symptoms can include dizziness, tiredness, nausea, paleness of skin and fainting.

It is also a good idea to pay attention to the humidity of the air. The more humid the air, the harder it is for sweat to evaporate, and so the cooling mechanism of the body struggles. Note that it is not necessarily true to say that you produce more sweat when it is humid (it is surprisingly hard to find concrete data on this subject!), although it may feel like this since the sweat remains on your skin or in your clothes. But what is certainly true, is that you are at more risk of overheating. In fact, in the same way that there is the fairly well known idea of "wind chill", there is the perhaps less well known (in the UK, at least) idea of a "heat index" (or "humidex", which is slightly different but essentially the same idea). A heat index combines the temperature and the humidity of the air, to give an idea of how hot it "feels". It reveals what we perhaps instinctively know already - humidity can have a huge effect on how well our bodies cope with the heat.

Heat exhaustion, however you choose to define it, has a reputation of being very easily reversed. Finding a cool spot (if that is possible), resting, water and salty food, or fluids such as isotonic "sports drinks", can usually turn the situation around. However, if steps are not taken to deal with heat exhaustion, it can progress to...

Heat Stroke

When the body simply cannot regulate its temperature adequately, perhaps due to an environment that is too hot, perhaps due to dehydration, perhaps due to exercising too vigorously, perhaps due to a combination of these factors, heat stroke is a likely consequence. Heat stroke is a medical emergency. A body that can no longer cool itself adequately will gradually gain in temperature. Certain organs in the body have an incredibly low tolerance to being overheated. If they are raised just two or three degrees Celsius above their normal temperature, they begin to fail. In a worst case, heat stroke can lead to brain damage and death within minutes.

For this reason, while heat stroke is a medical emergency that really demands a hospital and trained medical staff, it is unlikely that any rescue effort can be arranged quickly enough. The best hope is that someone in the party will recognise a victim of heat stroke immediately, and begin first aid without pause.

Recognising Heat Stroke

While heat stroke can usually be prevented by paying attention to early signs of dehydration, hyponatremia, and overheating, it can also come about very suddenly. The possible signs of heat stroke are usually given as delirium, unconsciousness, rapid breathing and seizures. If, in spite of physical exertion on a hot day, the skin is dry, rather than moist from sweat, then this is a good indication of heat stroke - however, it remains quite possible that a victim of heat stroke might have wet skin.

Treating Heat Stroke

Every effort should be made to cool the body, and to ensure that it is not dehydrated. Some examples of practical first aid in a wilderness situation are:

If there is a water feature nearby, such as a river or lake, and it is safe to do so, then immerse the victim in the water - taking great care to ensure that they can breathe. While immersion in water is likely to offer the most rapid cooling possible, it can also present the obvious danger of drowning. It is also possible that the victim could be violent, delirious or having seizures, in which case entering water should be avoided unless there are enough people in the party to fully control the victim.
If a body of water is not available, move the victim to the coolest place possible. Try to find or create shade, and try to find a spot where there is air movement.
Feel around for the coldest ground to lie the victim on. This can depend on the time of day and whether the ground has been exposed to sunlight. For example, if it is the middle of the day or the afternoon, and the ground has been exposed to sunlight, a patch of grass is likely to be cooler than a slab of rock - but feeling it with your hands will be able to verify this.
Provided shade has been found or created, remove any clothing, to help the body lose heat into the air and into the ground.
If the skin of the victim is dry, wet it with water.
If there is inadequate natural air flow, fan the victim. Fanning can significantly aid the cooling of the victim, particularly if you first ensure that their skin is wet.
If the victim is conscious, they should be provided with water or isotonic "sports drinks" to drink. Avoid caffeine (tea, coffee, some fizzy drinks etc) and alcohol.
At the same time as, or immediately after first aid has begun, attempt to organise rescue and hospital treatment. Be aware that even victims that appear to recover from heat stroke, often have impaired temperature regulation for days afterwards. They can even fluctuate between suffering from hyperthermia (heat stroke) to suffering from hypothermia, so hospital treatment and monitoring should be sought in all cases.

If this article has got you all hot under the collar, then you can let off steam in our forums, here.

If you can't be bothered to enter the forums, then shame on you! But you can still leave a comment below. Please try to avoid the profane ramblings of a madman. That's our job.

Your Comments

On 3 March 2007, Mikey P said:
This all sounds a bit serious. Maybe I'll stay inside.

On 12 January 2007, Rod said:
We know of these things in Phoenix, AZ. Unfortunatly most people in Phoenix are from California. They treat heat stroke with mocha latte, iced. It preserves them nicely. It's a dry heat.

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