High Altitude Seriousness | Better Know It Better

High Altitude Seriousness

    You    Get    

ecstasy    joy    fulfillment    accomplishment

fun     enjoyment      memories

You Fight

Dizziness          Headache       Stomach Problems   Nausea          AMS        Loss of Appetite    HAPE    Cough    Confusions         Ataxia     Cold

Breathlessness   Fatigue      HACE      DEATH

Mountains rise up form the ground and the highest mountain peak in our world is Mount Everest, which is 8850 meters high from the sea level. However, the conditions on the top of Mt. Everest is not the same as that at our home. Its extreme and is difficult for human beings to survive for a long time there. Be it for achieving the summit or just for the love of it, human beings have challenged it and successfully achieved it.

Perhaps its the nature of us humans to accept the challenge and get over it. For the love of the mountains, humans have to venture outdoors as the mountains wont be coming to us, we have to go to it. Not only that, a mountaineer has to face lot of difficulties including harsh and extreme weather, living and sustaining out of one's comfort zone, exhaustion and the most important of them all - High Altitude.

What is high altitude?

When venturing into the mountains, you have to climb it, and with that you gain altitude. Gaining altitude changes your body's adaptability capabilities. In mountaineering definition, below is the classification of high altitude

8000ft - 12000ft: High Altitude
12000ft - 18000ft: Very High Altitude
18000ft and above: Extremely High Altitude

What are the effects of high altitude on humans?

As we know that with increase in altitude, the atmospheric pressure decreases. The concentration of oxygen at sea level is 21% approximately and the mercuric pressure is approximately 760mmHg.  Our body is very well adapted to this conditions. However, at high altitude, the concentration of oxygen remains the same, but since the pressure decreases, the oxygen molecules are now far apart from each other compared to that at sea level. So, we now start receiving less oxygen molecules per breath. This is the trigger to all what cascades after that. At around 5000meters, the pressure is approximately half compared to that at sea level and at the summit of Mt. Everest, its one-third. Our body is not just used to this deficiency of oxygen in our blood, hence we face several problems which clubbed together is called Acute Mountain Sickness ( AMS) or simply Altitude Sickness.

What is Acute Mountain Sickness?

As described above, AMS is caused by our body's inability to adapt to the high altitude. The shortage of oxygen in our blood triggers Hypoxia - deficiency of oxygen in our body. As a result of Hypoxia, our body shows symptoms like headache, dizziness, fatigue, breathlessness, nausea, feeling vomitish, etc. These symptoms clubbed together is called Acute Mountain Sickness.

Symptoms: headache, dizziness, fatigue, breathlessness, nausea, feeling vomitish, loss of appetite

Treatment: resolves on its own. Mild analgesic or ibubrufen may be given for headache. Hydrate the victim. Keep a strict watch on the victim. Restrict further ascent until the symptoms vanish, else descend if symptoms persist.  You may put the patient on Acetazolomide ( Diamox - 125mg twice a day post food, if required 250mg twice a day). Still, if symptoms persist, descend is the only solution.

How serious can it be?

Usually, AMS heals on its own when ample amount of time is spent at that altitude. However, further ascend should not be allowed if the symptoms do not resolve. AMS should always be seen as a dangerous alarm for two of the deadliest and fatal conditions at High Altitude - High Altitude Pulmonary Edema (HAPE)  and High Altitude Cerebral Edema (HACE). 

If AMS alarm is not heard, you might be taking yourself to your death bed high up in the mountains.

What Is High Altitude Pulmonary Edema (HAPE) ?

HAPE is a condition in which the pressure in our pulmonary artery increase so much that it ruptures the week capillaries, specially that of our lungs which is badly Hypoxic. This results in leakage of fluids in our lungs and we have difficulty breathing. HAPE generally happens on the second night, but you should always be on check. Cold conditions increase artery pressure, and increase chances of HAPE.

Symptoms: Breathlessness at rest, fast and shallow breathing, extreme fatigue, cough, sometimes blood in cough, gurgling breaths and dizziness.

Treatments: You cannot treat HAPE at high altitude. You can only reduce the symptoms by giving drugs like Nifidipine ( 8mg). Provide supplementary Oxygen. Victim should be kept warm. Sometime, you might put the victim on Acetazolomide (Diamox) + Nifidipine. Stop any exertion, even while descending. The ultimate course of action is immediate evacuation as soon as possible, even during night if required. The symptoms resolves on descend, but the victim must be taken to hospital for proper management.

Caution should be made not to confuse HAPE with bronchitis, pneumonia or asthma. A HAPE patient will improve on descending. 

 

What Is High Altitude Cerebral Edema (HACE) ?
 

HACE is a condition in which brain functions improperly due to the effects of altitude. The pressure in the cerebral membrane increase and the brain swells. It can be very dangerous and sometimes might not give you time to react. 

Symptoms: Loss of cordination ( ataxia), ability to think, change in one's behavior, agressiveness, irritated behavior, confusion.

Treatments: Similarly to that of HAPE, high altitude is not the place to treat HACE. Only solution is to descend, and HACE patients show quick signs of recovery on descending good altitude. Medicines like Dexamethasone ( 8mg) can be given, sometimes along with Acetazolomide ( Diamox) to give you time to work out evacuation, if required even at night.

 

How do a human body adapt to high altitude naturally?
 

To our relief, our body is a miracle machine. Acclimatization is the process by which our body adapts to the extreme conditions of High Altitude Hypoxia.

Acclimatization is a biological process in which our body reacts to the conditions of deficiency of oxygen by increasing the count of Hemoglobin in our blood, which are the oxygen carriers. However, as a result of same, our blood thickens and hence its overload on our heart to pump thicker blood to the distant organs like fingers and toes. So, high blood pressure is normal at high altitude, which is not the case at low altitude.

Acclimatization is a process which takes time depending on the individual body. Few acclimatize faster, whereas few take little more time. There are two kinds of acclimatization - Shorter and Longer. Longer acclimatization might take long time. The approximate formula is the altitude in kilometers multiplied by 11.6 days. So to acclimatize for a normal trek that goes up to 4000 meters, it might take 4 X 11.6 = 46 days!!

Acclimatization has 3 rules, which if followed, maximum acclimatization can be achieved.

Climb High Sleep Low
Slow Ascend, Do Not Over Exert
Hydrate Hydrate Hydrate

 

What is Diamox? How does it help?

Diamox is acetazolomide which aids faster acclimatization. Diamox is a diuretic and helps the kidneys excrete the bicarbonates. As a result of Hypoxia, our body breathes rapidly, which decreases the saturation and partial pressure of CO2 in our body. This increases the ph of our blood and makes it alkaline. Use of Diamox re-acidifies the blood and acts as a respiratory stimulant.

Dosage: 125 mg 12 hourly. For very high altitude, 250mg 12 hourly, post meals.

DIAMOX DOES NOT HEAL AMS, IT JUST SPEEDS UP ACCLIMATIZATION. PEOPLE EVEN ON DIAMOX DIE OF HAPE AND HACE.

 

What is Periodic Breathing?

Periodic breathing is a irreegular pattern of breathing that occurs at high altitude, specially during night. The breath might stop for  few seconds and it might create tremendous anxiety preventing you to sleep further. Do not worry, its normal, and betters with proper acclimatization. Diamox helps with periodic breathing, 125 mg before sleep.

Sleeping is very important to you as a better sleep means faster acclimatization and better recovery for the next day

 

Does sleeping pills help?

Sleeping pills should not be taken at high altitude. It might throw you into problems at high altitude to AMS. Melatonin is an OTC sleep aid that helps many and has no contraindications at altitude. One prescription sleep aid that has shown NOT to disturb breathing at sleep is zoldipem; you may want to discuss taking this medication with your personal physician. Any other hypnotics/tranquilizers should probably not be used at altitude.?

 

this blog also appears on: https://himalayanhigh.in/high-altitude-seriousness-better-know-it-better

Subjective Hazard - The Human Error Factors In The Mountain

Your venture into the mountains are risky and many hazards are involved in it. In mountaineering terms, we classify those into 2 types of Hazards - Subjective andObjective. Of the 2 hazards in the mountains, subjective hazard is often seen as a reason for lots of major and minor accidents in the mountains. Subjective hazards are the human error factors in the mountains which most of the times can be kept off by being aware of the risks and thereby, planning and preparing for those.

Any hazard in the mountain is a serious situation and has to be faced bravely and strategically to bring oneself back to safety. Being knowledgeable helps. Let me list some of the most frequent subjective hazards we encounter on a trek or a mountaineering expedition and how to plan better to avoid them.

What Are The Various Subjective Hazards In The Mountains

Slip, Fall, Bruise, Twist, Fracture: 

While on a trek, you will encounter lots of trail sections which will be slippery..  a wet muddy landslide section, verglas, hard snow, slippery rocks, thin ice covered rocks and sometimes even small pebbels scattered terrain. Crossing a scree too bears the problem which is more of a objective hazard. However, some objective hazard are raised due to the subject, hence had to be kept in mind (explained later below ). Careless steps in these section can result in a slip and fall, which can cause deep bruises, twist your ankle or even result in a fracture at times. Remember, in the high altitude, deep bruises are not goo too !!

Prevention: Get your shoes according to the terrain you will be venturing into. Research the area well before you plan your trek. If you are trekking on your own, call your guide to enquire about the route. If its a organized tour, call your operator and enquire about the route. Most importantly, learn if there was a recent changes in the route due to landslide or so. Your guide might not know exactly, but it will give you an idea about majority of the route. Not just that !! It will send important message to your guide or operator that you are concerned about the safety.

Ankle protection in your shoe should be a must and is very important in that rough irregular terrain. I have seen trekkers twisting their ankles in front of my eyes because of no ankle protection. Some trekkers I don't know why do not tie the shoe lace properly and leave open the last hooks which actually provides the ankle protection. I believe they are the ones who loves to learn from a bad experience and does not like heeding to safety instructions. I usually go rough in the route banking on my ankle protection and it has always worked good for me. 

Secondly, when I say choose your shoe according to the terrain, I mostly mean the sole as per the context of this article. ( Water proofing will be covered below under a separate hazard ) Your sole will protect you from slipping. Some soles are good for snow, while some for mud, some for slippery rocks. Explaining shoe soles is out of scope of this article. 

Be careful while trekking on a risky area. Follow instructions and use support if required, like trek pole, ice axe, or simply your hand if possible.

Always anticipate these conditions. I remember a scenario in which a trekker had an accident when she was just coming out of her tent which was pitched on snow. When they arrived at the campsite, the snow was soft and easy to walk around the campsite. But with sunset, the upper layer of snow became hard and slippery. The trekker slipped as soon as she stepped out of the tent assuming it to be safe, but fell down twisting her ankle. Has she put on the laces properly before coming out of the tent, rather than just slipping on the shoes, she could have prevented the injury.

Snow Blindness:

Snow is a temporary inflammation of the cornea of your eyes due to continuous exposure to UV rays which causes temporary blindness and might also result in permanent blindness if not taken care of properly. People suffering from it says it is very painful. Concentration of UV rays are higher at high altitude and with snow surrounding you, it reflects the UV rays into your eyes. Hence, your eyes are exposed to UV rays which terribly irritate your eyes. Fresh snow are more harmful compared to old melting snow which has a layer of mud over it. Crossing the glacier zone covered by snow needs precaution.

Symptoms of snow blindness are blurred vision, painful and watery eyes.

Prevention: Snow blindness can be kept off by wearing a well polarized sun glasses which cuts off the glare and reflects back the harmful UV rays reaching your eyes. Make sure your eyes are protected from sides too, as UV rays entering from the sides of your sunglasses harm your eyes as well. Glacier goggles are well covered from both the sides. Nowadays, you get other sunglasses too giving you the protection from the sides. If not, improvise. Sunglasses with blue filter are not advised on the mountains as continuous exposure to blue light is harmful for your eyes and might cause retinal damage. Polarized Anti UV Sunglasses are a must if you are venturing in high altitude and even low altitude snow bound areas. Take special care of your porters for this. Check that they are well equipped before the trek.

Care: If you are somehow having painful eye condition in your trek, get into your tents and cover your eyes with dark cloth, preferably black. Stay indoors until you are completely healed. Use eye drop or ice to control the pain. You should be OK in day or two. If not, seek doctors help by returning back to the base. Further exposure to UV rays may harm your eyes more and cause permanent blindness.

  

Cold Injuries - Chilblain, Frost Bites, Hypothermia:

Cold Injuries are one of those subjective hazard which comes from either unpreparedness or over smartness. You need to be aware of the environment and situations which are the causes of cold injury and prepare well to fight those. I have seen and know of people return from treks due to cold injury and sadly everyone I know of were TREK LEADERS !!

Isn't it disgusting to see your trek leader return from the trek because of a cold injury, not because he helped a trekker from an accident, but because of his lack of knowledge or lack of preparedness. I mean, how or what did he ask his trekkers to prevent cold injuries ??  Well, sadly, some of the biggest Trek Operator in our country hire trek leaders like that.

There are several cold injuries and those which mountaineers and trekkers are mostly subjected to are chilblain, frostnip, trench feet, frostbites 1st degree, frostbites 2nd degree, frostbites 3rd degree, frostbites 4th degree, Hypothermia, etc.

Frostnip and Chilblain

Frostnip and Chilblain are probably the first signs of cold injury caused by the exposed skin like nose, ear lobes and cheeks, mostly occurs due to chill wind hitting your face or exposed skin. It starts with redness in the exposed area which changes colour and darkens to purple and then blue black. It is painful and the extreme points often itches. The difference between frostnip and chilblain would be that frostnip does not include cellular damage but chilblain does. Chilblain can be considered as the starting point of a higher degree frost bites

Prevention: A simple prevention method of chilblain is to keep yourself covered, specially when chill air is blowing. Use gloves, socks balaclava or scarf, covering your ears and fore head. Take care of the cold wind hitting your exposed skins.Usually your shoe will have a rubber layer in front. Its important to insulate the toes. Use layering in socks. If you feel cold, consciously keep pumping blood into your limbs and fingers. Sometimes in a stranded situation, you need to do thigh ups to keep yourself warm. Its the first line of defence, and if taken care of properly, you can keep away with greater damage. I know of persons who have saved themselves by doing thigh ups through the night when they were stranded due to bad weather in Jaonli.

Care: Keep the affected part dry and warm. Wash it with dilute Betadine or Iodine solution and pat dry. Keep the areas free with frequent movements. It take a week to heal when kept under check.

  

Frost Bites

When our body is exposed to cold temperature for a longer period of time, it defends itself by maintaining the temperature of the core and vital organs, thereby restricting blood flow to the extremities like fingers and limbs. This survival strategy of our body causes the cells and tissue of the extremities to die slowly because of lack of blood flow. This slow dying of soft tissues, nerves and blood vessels due to freezing is called frost bite. It is categorised into different stages as per the degree of damage and pain. Signs and symptoms may be pain in the affected area which slowly starts to get numb and discoloured. The colour changes from red to blue black to black as it degrades.

Frostnip is considered as a first degree frost bite. Second Degree frost bite is a step higher than frostnip and the sign presents in form of hardened skin layer with blisters, which looks greenish in colour. Numbness starts to click in but the sense is not lost. Further exposure to cold can bring in numbness and senselessness getting into Third Degree Frost bite. The blisters start to turn purple and pain starts to fade away due to the dying of nerve cells. Nerve damage restricts the usability of the limbs and fingers. A grade even higher to this is the Fourth Degree Frost bite in which the blisters and skin change colour to black and looses sense and usability. The affected part is often required to be amputated due to gangrene.

Prevention: Frost bite are mainly caused in snow bound areas. Its very unlikely to suffer from frost bite in a trek, but if you are venturing in snow bound areas, then you need to trek in a water proof shoes to protect your feet and socks from getting wet. Often, a snow storm may strand you for days making you prone to frost bite. Mountaineering boot are two layered with a plastic outer. Use of gaiters in deep snow is essential to save snow from getting into your shoes from the top. Water proof trousers should be worn to protect from rain and snow and similarly a poncho or a water proof jacket to protect from getting wet. Keep moving your fingers inside your shoes to increase blood flow which will keep you warm. Using layering to retain body heat.  Body warmers can also be considered for use.

Care: I am no expert of a frost bite to suggest a care. First aid actions should be to try and slowly rewarm the area with luke warm water and restricting motion of the affected area. Rest, seek medical help at the earliest. 

 

Hypothermia

Hypothermia is a condition in which the body temperature gets abnormally low creating a threat to life. Its an extreme condition which is rarely objective and mostly subjective in nature. This condition can be avoided with proper care. 

Prevention: Firstly, you need to carry proper clothing meant for the cold environment to keep yourself warm. You should take all precautions to not get wet and if by any chance if you get wet, take care in getting dry as soon as possible. Putting on wet clothes draws heat from your body and hence drops your body temperature. If you are venturing in snow bound areas, then you need to trek in a water proof shoes to protect your feet and socks from getting wet. Use of gaiters in deep snow is essential to save snow from getting into your shoes from the top. Water proof trousers should be worn to protect from rain and snow and similarly a poncho or a water proof jacket to protect from getting wet. Not just yourself, but you should also take care in protecting your rucksack and clothes within your sack to prevent from getting wet. Your fingers get cold too quickly. Keep moving your fingers inside your shoes to increase blood flow which will keep you warm.

Care: Keep yourself dry and warm. Use warm water for drinking. If you even feel cold, rub your feet and palm to generate heat. Take a hot water bottle into your sleeping bag. Use 2 sleeping bags if required. Use body heat to warm your fingers,palm etc. Our armpits, pubic areas are warmer areas in our body. Use those areas to heat your hand. If that does not help, get help from your friend's body. 

Trench Foot:

Trench foot is caused when your foot is wet inside your shoes due to sweat or water for a long period of time. Spending too much time in wet sock with tight shoes can cause it in just some 10 hours time. It is painful when you remove your shoe and dry it. If the skin has started to decay, bad smell will come too !!

Prevention: Keep your feet clean and dry, inside your shoes. 

Care: Keep your feet open and dry in warm indoors conditions. It should heal on its own within a day. If the condition is bad and tissue decay has started, check a doctor immediately.

Unplanned Bivouac Camping:

Bivouac camps are camps in which you either sleep in open or an improvised shelter with whatever resource available. It is often planned but the unplanned ones are to be categorized under subjective hazards which mostly is a result of a bad overestimated plan or sloppy execution. Sometimes it may be because of bad weather conditions as well.

Prevention: Plan well. Always carry few things which can be improvised to make a shelter. Even carrying a good sleeping bag helps at times.

Care: If you are in a group, sleep closer. Nowadays, 2 sleeping bags can be zipped to form 1 bigger sleeping bag. Beware of wild animals. Choose your shelter appropriately. In snow, mountaineers dig it to make a bivouac shelter. These are warm. 

Stomach Problems

Stomach problem usually happens due to water and food poisoning. It is a delicate thing causing severe outcomes sometimes costing a summit or retreating back. Take proper care of drinking water. Purify it before drinking. Eat with clean washed hands. Wash fruits before eating.  Read the below links for further prevention.

How To Treat Drinking Water On A Trek

How To Prevent Diarrhea On Treks

Improper clothing

Sounds simple but a very important factor. Properly plan your clothes and other packing items before heading to the wild.

Learn the best practices here: http://himalayanhigh.in/best-practices

Impact Of Trekking On The Environment

Venturing deep into the Himalayas give you a memorable experience for lifetime, but it comes at a cost, not just your time and money, but also at the cost of our fragile nature which is the root of our very own existence !! Listed below are few of the impact of trekking on the environment which we could think of..  perhaps there are lot more

Pressure on natural resources: Trekking impose a huge pressure on the natural resource of the land, most preciously on the fire woods for the extra warmth and fun of camp fire. Often campfire are not a sheer necessity, but used for fun and not on every occasion importance is given to create a low impact fire. Earlier, on treks fire woods used to be used for cooking as well imposing a lot of demand on the resource, but luckily now, for the good, trekking groups carry either a kerosene stove or gas cylinders which releases the pressure on the it. Even on tea house facilitated treks like Sandakphu in India,  or other treks in Nepal, part of the pressure is absorbed by cooking on gas, but cooking on fire wood is still practiced on these treks majorly, specially for continuously boiling water.

Other forms of pressure are the wild plants which some locals eat. Closer to the villages, they can be cultivated and consumed, but in the deeper treks, that should not be practiced. Himalayas are home to lots of species of medicinal plants and flowers. They are plucked by the locals and sometimes even the trekkers. Most common example of this can be the Brahma Kamal and Junipers which are found on higher altitudes. The caravan of mules joining the group does not help much which put further pressure on the natural resource.

Bigger the group size, higher is the pressure on the natural resource.

use of firewood to dry wet shoes on a trek

Soil erosion: Deforestation leads to soil erosion. The demand on the forest wood for cooking and fun activities increase deforestation. Construction of tourist infrastructure also results in deforestation but it has other advantages in the long run to sustain the growth. We all know the long term effects of soil erosion which causes unnatural degradation of the mountains and even causes landslides and rockfalls.

Widening of trail and destruction of plants due to trampling. Trekking causes trampling and it causes to widen the trail, create multiple trails and also increase soil erosion. It is advised to stay on the single trail when on trek and not to take short cuts on a new route. Trampling spoils the plantation and reduces regeneration. It damages the stems and results in no growth making it a new trail. On the other hand, trampling also damages the soil quality and water permeability. 

Brahma Kamal, rare Himalayan Flower are plucked for medicinal value, decorative purpose, curiosity and offerings to god

Non-Biodegradable waste. Perhaps the most talked about problem in the mountains. The litter of non-biodegradable waste by trekkers and the staff accompanying them is offcourse the most of the serious problems for the environment. Trekkers often venture deep and high into the mountains where there is NO MUNICIPALITY to take care of your waste, if at all they worked, even in the cities and towns.  Plastic forms a major cause apart from tin cans and glasses. The problem plastic has on the environment are well know and to list few of them , we may go with

1. Degrade soil fertility
2. Lessen soil water permeability
3. Change the chemical composition of the soil
4. Block water sources causing a breeding ground for diseases
5. The roots of small plants cannot penetrate through them
6. Disturbs the scenic beauty of the place

waste left over by trekking groups in Kashmir Great Lakes Trek, India

Listed below is a table of approximated time for compounds to biodegrade in a marine environment ( taken from Wikipediahttps://en.wikipedia.org/wiki/Biodegradation)

Product	Time to Biodegrade
Paper towel	2–4 weeks
Newspaper	6 weeks
Apple core	2 months
Cardboard box	2 months
Wax coated milk carton	3 months
Cotton gloves	1–5 months
Wool gloves	1 year
Plywood	1–3 years
Painted wooden sticks	13 years
Plastic bags	10–20 years
Tin cans	50 years
Disposable diapers	50–100 years
Plastic bottle	100 years
Aluminium cans	200 years
Glass bottles	Undetermined

Chemical contamination of food and water consumed by wild animals disturb their mental health. May be you thought that leaving behind some food is OK as it is bio degradable, but not always are you correct. Mostly preserved food are taken on treks and these contain chemicals which are harmful for the animals in the long run. There are examples of genetic changes occuring in animals due to consumption of chemical waste. So not all products that are biodegradable are good for the environment. So is the contamination of water by detergents and soaps not good. Keep the food chain in mind.

Frequent sighting of humans by wild animals disturbs their natural instincts. Wild animals are shy and love to be on their own. Human intrusion into their territory disturbs them.  It effects their mating cycle and also psychology effects their mental health for which they might need to face consequences. They might loose the fear of human which can bring the closer to the humans building a platform for a clash. The vice versa may also result in clash. History is a proof of the effect of animal and human clash, but remember we are all related to each other !!

Faecal contamination of soil and water bodies: This has very much to do with chemical contamination of the soil and water. We humans eat lots of chemicals in the form of preservatives in our food. Wild animals and plant do not. Improper disposal of faecal and other human waste pollutes the area. Sometimes, even proper disposal does.

Cascading effects. Probably the worst of all. We humans have the tendency to follow and be irresponsible until the problem hovers on ourselves. A dirty place will be further piled upon with a dump. We leave things upon our followers saying or thinking that he or she or them following will do the clean up job, without even thinking that they are thinking the same too, until a LEADER walks on that path. Our this particular manner has even costed life in mountains like Everest, keep aside cleaning a area.

With these many listed impacts on the environment, I just imagine what all may be the unlisted ones, which did not hit my mind !!  

But does that mean we do not trek and see the beauty of the nature ? We too are Nature's own creation !! Should we stop our friends from trekking ??  Should we not allow our future generations to experience the wonderland ?? No, the answer is NOT. We Do Not have the right to do so.

Only WE can make it better. Only WE ourselves can help us out of this. Its US who together can solve this problem. We just need to be Responsible Trekkers, Practice it and Preach it. In each of our actions, we need to lead by examples and not just make it a SLOGAN !!

Hope for the best !! 

this blog also appears on: https://himalayanhigh.in/impact-of-trekking-on-the-environment