Thursday, August 11, 2011

HEAT AND COLD STRESS ON CHEMICAL TANKERS -- CAPT AJIT VADAKAYIL




  SURVIVAL TIPS EXTREME HEAT AND COLD ON CHEMICAL SHIPS



Chemical tanker men work on low freeboard decks at sea for MANUAL tankcleaning in cold icy winds and sea spray or they could be wearing nil-ventilated PPE in hot weather in port in direct sunlight, doing stripping or manual valve topping up.



Knowledge of effect of heat and cold on human body is important to prevent LTI and ill effects to health.



Master must do a risk assessment when there are chances of heat or cold stress to his crew.



HEAT STRESS:



Elevated humidity or wearing chemical resistant splash suits reduces the ability of the body to evaporate the sweat and cool it, and increases the heat load . This can be made worse by radiant heat of the sun while on deck.



Heat rashes can even affect sleep , during off duty hours.



Radiant heat could be from  steam coils while squeegeing the cargo inside the tanks. The physical work which has to be done FAST increases the heat load on the body.



The crew members sent to sweep the tanks must be physically fit , with zero blood alcohol levels. They must keep the body hydrated by drinking water to prevent heat exhaustion.



Salt tablets can replace the sodium lost from the cells. The sodium is like acid in a car battery’s electrolyte.  Salt depletion can cause debilitating body cramps. Heat Cramps are painful muscle spasms. Tired muscles, usually those used for performing the work, are usually the ones most susceptible to cramps. Cramps may occur during or after working hours. The pain and cramps in muscles, begin in the calves and spreading to the arms and abdomen



Heat Syncope (pronounced sin-cope-ee) or fainting may be a problem for an individual not acclimatised to a hot environment, and who simply stands still in the heat, like at the gangway / manifold watch. This is caused by blood pooling in the veins in the legs, which reduces blood pressure and can cause fainting



Heat stress can cause lack of concentration, irritability, tiredness and poor work performance.  It causes heavy sweating, headache, rapid breathing, intense thirst, and vomiting. The skin is clammy and moist, the complexion pale or flushed, and the body temperature normal or slightly higher.



Heat Stroke is the next stage after heat exhaustion. It is very serious and can be life threatening, as the body can no longer regulate its own temperature. Symptoms include hot red skin, but usually with no sweating, possible rapid pulse, difficulty in breathing, confusion, vomiting, and eventual unconsciousness. Permanent health effects or death may result.



It is essential that the early signs of Heat Stress are recognized,and suitable corrective action taken, so that potentially fatal Heat Stroke is avoided.



Actual Heat Stroke must be treated as a MEDICAL EMERGENCY and should be processed accordingly. Precautions

where Heat Stress is a potential hazard, all persons on board, especially supervisors, should be trained on the health hazards, symptoms, and methods to protect themselves from Heat Stress related disorders.



Training sessions on Heat Stress should be periodically included as an item in the Vessel Safety Meetings.



During periods of high ambient temperatures, a pre-job risk analysis using Work Permits, where applicable, and/or a Job Hazard Analysis (JHA) must be completed. This risk analysis prior squeegeing heated palm oils and fats  should consider the potential for Heat Stress, and should be communicated to the individuals involved, prior to starting the job.



Each individual should monitor any symptoms of Heat Stress in their own body. It is likely that the first symptoms will include feeling dizzy, weak, or light-headed. Some individuals notice excessive sweating or feel the pulse in their head. All personnel should look out for any other individuals who are, or appear to be, suffering from the heat exposure. Symptoms of Heat Stress should not be ignored, because of pressure of work.



The consumption of sufficient quantities of water in order to avoid dehydration is vital. In normal conditions, the body loses 2.5 litres of water in a day, but when performing strenuous work in the heat, this quantity can increase to 1.01.5 litres of water in an hour. Thirst only occurs when there is already some dehydration, so water should be drunk even when not thirsty. Individuals should be encouraged to drink one cup of water at least every 15 minutes, if not more frequently. Urine should be light in colour, and of normal volume. Salt supplementation is NOT required. The body obtains all the necessary salt from a normal diet.



As stated above, new employees from cold countries ( fair skinned crew ) just returned after leave , may require a period  of 3 days of ‘acclimatization to cope with hot work environments. The acclimatization process is lost, if exposure stops for prolonged periods of time.



In areas where Heat Stress is possible, Heat Stress management should include the following:-

Administrative measures such as regular breaks, taking breaks in a cool refuge, accessible drinking water, and minimisation of physical work rate.

Modified engineering and work practices, including shading with parasols , reflective barriers for radiant heat, temporary insulation barriers, spot cooling from a fan, air ducting or air conditioning, personal cooling devices, and special scheduling in order to carry out heavy work at a cooler time of day.



All personnel should limit their own exposure to heat as far as possible, and take breaks in a cool environment, when necessary. Do not wear unnecessary clothing, e.g. T-shirts underneath boiler suit overalls. First aid plans and medical arrangements must be in place to treat any individuals overcome with Heat Exhaustion and Heat Stroke.



The colour of an individual's urine is a simple method for monitoring their state of dehydration. Basically, urine should always be very light in colour. The darker it gets, the more dehydrated the individual is. It is very important, even if individuals are only mildly dehydrated, that they increase their consumption of water. Additionally, they should need to urinate, at least, at the normal frequency.



Emergencies and first aid

If any individual suffers from an effect due to exposure to heat, they must obtain prompt medical attention, and inform there supervisor. If anybody observes that any other individual is suffering from the effects of heat, or is faint or unconscious, they must:-

Remove the individual from the hot environment,

Obtain medical attention immediately,

Cool the individual down preferably by moistening the skin and fanning it.

Do not immerse the individual in cold water.

Keep the individual horizontal,

If there is vomiting, make sure the airway remains open by turning the individual on to their side.





COLD STRESS:



There are many publications on board ( like training manual ) which give precautions for cold and hypothermia.



The body is made up of a central core containing the vital organs (brain, heart and kidneys) which needs to be maintained at a constant temperature of 37oC (98.6oF), and a peripheral envelope made up of skin, muscles, fat and bones, whose temperature can vary greatly without ill effects.



An individual gains body heat from food and muscular activity, and loses it at approximately the same rate to the environment, thereby maintaining a constant core temperature. Additionally, if the core body temperature drops below normal, the peripheral blood vessels constrict, decreasing blood flow to reduce heat loss from the surface of the skin, and shivering generates heat from muscular activity. This also helps maintain a constant central core temperature.



Key factors for Cold Stress :

Low temperatures from being in refrigerated compartments, being immersed in cold water, atmospheric conditions such as strong winds, cool winds (or both), and sea spray/ rain or dampness are all environmental factors that can cause Cold Stress.

Wind chill, which is a combination of ambient temperature and wind velocity, is a crucial factor when working outside. For example, when the actual air temperature of the wind is 4oC , and its velocity is 30knots (56km/hr), the exposed skin experiences conditions equivalent to a still-air temperature of 12oC !  A dangerous situation of high heat loss can therefore occur for any individual exposed to high winds and low temperatures.



Other risk factors that contribute to Cold Stress by increasing susceptibility or the effects of the cold include:-

Wearing inadequate or wet clothing,

Taking alcohol, nicotine or caffeine,

Taking certain medications,

Having a cold,

Having certain medical conditions, such as diabetes and heart disease,



The human body ( especially dark skinned crew ) is generally not well equipped to cope with a cold environment, and prolonged exposure to low temperatures may cause:-



Frostbite

This is caused when ice crystals form in the tissues of exposed body parts. If only the superficial tissue is involved, this is known as "Frostnip". This can destroy tissue or lead to an infection. The first signs of frostbite include pain in the nose, fingers or toes, which eventually turn pale and numb. Frostbite is serious, if the skin starts to harden or turn blotchy or blue.



Trench Foot ( or Immersion Foot)

This occurs when an individual stands in water at nearfreezing temperatures, for extended periods. There are

three stages of Trench Foot:-

In the mild stage, there is red skin, swelling and numbness,

In the moderate stage, there is bleeding and nerve damage,

In the severe stage, there will be gangrene.



Hypothermia

This occurs when the body loses too much heat and becomes cold, and may result in death. Early signs are blue lips and fingertips, shivering, slurred speech and stumbling or falling.



Here are the effects of hypothermia in more detail, related to the core body temperature:

Core temperature Deg C hypothermia effects

37o  Normal body temperature

36o  Judgement may be affected

35o  Feels cold, looks cold (blue lips and fingertips), Severe shivering,



Definition of hypothermia threshold.

DANGEROUS HYPOTHERMIA BELOW 35oC.

34o Change of personality (becomes withdrawn, or ‘switches off’),

Confused, slurred speech, stumbling or falling, inappropriate behaviour, e.g. sheds clothing,lack of appreciation (doesn’t care).

33o  Consciousness clouded, shivering stops, incoherent.

32o  Heart stoppage a significant risk, heat loss will continue unless protected, limbs stiffen.

31o  Becomes unconscious.

24o  Survival unusual if any colder.



Cold can also exert an adverse psychological impact. Discomfort and tiredness, due to the body using energy to keep warm, can lessen an individual’s concentration, and can result in increased errors and accident rates.

There is also an increased risk of accident or injury, as fingers can become numb and immobile, and impair an individual’s ability to carry out delicate tasks, hold objects, climb ladders etc.



There are a number of additional effects of cold:



Chilblains.

These are an inflammation of the hands and feet due to exposure to cold and moisture.



Fingertip fissures.

These are deep and very painful, and can occur where the fingertips are exposed to prolonged, or repeated cold conditions.



Cold Burn.

This is the instantaneous freezing of skin when touching a very cold object, especially metal,



Windburn.

This effect causes dry skin.



All personnel should learn the signs and symptoms of the effects of Cold Stress, and what to do to help any other affected shipboard personnel.



Appropriate protective clothing that is specially designed for cold weather should be worn, with special attention being given to covering the feet, hands, face and head.  SILVER COLOUR (FOOD ALUMINIUM FOIL) IS A BAD ABSORBER AND BAD RADIATOR OF HEAT.



(Note: Up to 40% of body heat can be lost through the head when it is exposed!) Warm gloves and hats should be worn, and footwear that is not too tight. Multiple layers of clothing can be more effective than, single layer but thicker clothing.



Also:-

 Avoid conditions and activities where possible, which cause sweating, as this can soak clothing, which reduces its insulation ability, and can increase heat loss by its evaporation.



And avoid having wet feet for long periods of time, and ensure socks are dry before putting them on. Remove wet socks and footwear after work. If the feet become wet, then dry them thoroughly and massage them to promote circulation.



There are a number of controls which can be used to keep warm:-

Make the best use of on-site sources of heat,

Shield work areas from draughty or windy conditions,

Use a heated shelter where there is prolonged exposure to the equivalent wind-chill temperatures of -6°C (21°F) or colder,

Where the air temperature is below -29oC , or an equal wind-chill effect exists, the ships management team will decide whether to continue operations that involve working outside. If operations proceed, the SMT will determine and implement precautions (e.g. taking regular breaks in a warm refuge, and monitoring the condition of all individuals).



There are also some safe working practices which should be adopted in exceedingly cold conditions:-

Allow for a period of adjustment to the cold before embarking on the full work schedule,

Set an appropriate pace of work, with extra breaks being taken when needed, Reduce the number of activities performed outside, as much as possible,

When it is necessary for individuals to work in these cold conditions, the work should be undertaken during the warmest hours of the day, and any activities involving lengthy periods of static posture should be minimized,

Ensure individuals remain hydrated, e.g. drink fluids,



Use a buddy system during outside working, ensuring no individual is working on their own.

Apply moisturiser to dry skin.

Remember try to KEEP WARM AND DRY!

STAY ALERT to your own needs and problems, and the needs and problems of other shipboard personnel.



Emergencies and First Aid

Cold Burns

If a body part becomes attached to cold metal, warm water or other fluid (even urine) should be used to gently separate the body part from the metal.



SEEK MEDICAL ATTENTION.

Frostbite:-

Move the individual to a warm dry area and apply warmth, such as body warmth from hands, to the affected part.

Do not leave the individual alone.

Breathe on to the affected part, or place the affected area in water at body temperature, maximum 37oC.

Remove any wet or tight clothing, or tight jewellery that may cut off blood flow to the affected area,

Do not rub the affected area, because severe rubbing causes damage to the skin and tissue.

After the affected area has been warmed, it may become puffy and blister. The affected area may have a burning feeling or numbness. Do not break blisters that form as a result of frostbite. When normal feeling, movement, and skin color have returned, the affected area should be dried and wrapped to keep it warm. If there is a chance the affected area may get cold again soon after, do not attempt to warm the skin. If the skin is warmed, and then becomes cold again, it will cause severe tissue damage.



SEEK MEDICAL ATTENTION as soon as possible.

Hypothermia incurred on board:-

Move the individual to a warm, dry area. Remove any wet clothing and replace with warm, dry clothing or wrap the individual in blankets (i.e. keep the individual warm and dry),

Do not leave the individual alone,

Have the individual drink warm sweet drinks (sugar water or sports-type drinks) if they are alert; avoid strong drinks with caffeine (coffee, tea, or hot chocolate); warm milk or soup are alternatives,

Have the individual move their arms and legs to create muscle heat. If they are unable to do this, place warmbottles or hot packs, (maximum temperature 37oC(98.7oF)), in the armpits, groin, neck, and head areas.

Do not rub the individuals body or place them in a warm water bath, SEEK MEDICAL ATTENTION as soon as possible.



CAPT AJIT VADAKAYIL
( 29 YEARS IN COMMAND )

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