Heat Stress

My Life Monday

Doing too much on a hot day, spending too much

time in the sun or staying too long in an overheated

place can cause heat-related illnesses.

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Heat attack

Hot temperatures and high humidity stress the body’s ability to cool itself, resulting in heat sickness. It is important to recognise the symptoms at an early stage in order to guard yourself from serious consequences.

Know the difference

It is important to note the difference between various

heat illnesses.

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• Dehydration-is the loss of fluids from the body. The

human body needs water for vital organs such as the

brain, kidney and heart to function properly.

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• Heat rash- is a skin irritation caused by excessive

perspiration.

• Heat cramps- are severe and painful cramping of

the muscles due to imbalances in body fluids

and excessive perspiration.

• Heat syncope or fainting- dizziness that can

result in fainting when standing continuously

under the hot sun for a long time.

• Heat exhaustion- results when losing body fluids through perspiration during heat exposure.

The body cools off by evaporation of sweat but gets exhausted when the sweat exceeds the volume of water or fluid drunk.

• Sun burn- is a painful skin condition which occurs as a result of overexposure to the ultra-violent rays of the sun. This can damage the outer layers and inner tissues of the skin. It can also lead to skin cancer.
• Heatstroke or sunstroke-is a deadly heat illnesses.

It occurs when the body’s control temperature

system stops functioning. The body temperature

rises rapidly, the sweating mechanism fails and

the body is unable to cool down. This can lead

to death, brain damage or permanent disability if emergency treatment is not provided.

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How to recognise, treat and avoid heat illnesses?

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Temperature & Humidity Combined

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Below is a diagram indicating the temperature and humidity level that you need to be careful of.

Relative Humidity

Temperature

Engineering Controls

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• General Ventilation

General ventilation can dilute hot air with cooler air (generally brought in from the outside). This technique clearly works better in cooler climates than in hot ones. Large areas or entire buildings identified as high heat areas may require a permanently installed ventilation system to reduce temperature levels. In smaller areas, portable or local exhaust systems may be more effective or practical.

• Local Ventilation

Reduce heat stress by increasing the airflow and velocity with fans and other movers in the work area (as long as the air temperature is less than the person's skin temperature). If the air temperature is higher than about 100° to 104°F, skin warming may offset any advantage gained by evaporative cooling. Because this method does not cool the air, the increased air flow must contact the worker directly to be effective. This control will have little, if any, positive effect on workers wearing vapor‑barrier clothing.

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Engineering Controls

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• Air Treatment / Air Cooling

This control measure differs from ventilation because it cools the air by removing heat (and sometimes humidity). Air conditioning and air treatment devices may be expensive to install and operate. Nonetheless, mechanical refrigeration can be effective in specific areas such as "cool rooms" (used as recovery areas near hot jobs). Portable blowers with a built‑in air chiller are effective for cooling asbestos abatement (and similar) enclosures. The main advantages of blowers are portability and minimal set‑up time.

• Radiant Heat Reduction

Reflective heat shields and insulation will reduce radiant heat. With sources of radiation such as heating pipes, it is possible to use both insulation and surface modifications to achieve a substantial reduction in radiant heat. If shields are used, it is important to minimize their influence on the cooling effects of air flow.

• Shade

Shade will reduce radiant solar heat and is a widely recognized control measure. Shading the work area, rest areas, or equipment or enclosures can significantly decrease the heat load.

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Administrative and Work Practice Control

• Scheduling

If possible, perform potentially hot jobs when heat stress conditions are at their minimum. Allow latent heat in equipment to dissipate before work begins. Schedule work for the cooler part of the day, and schedule routine maintenance and repair work in hot areas for the cooler seasons of the year.

• Fluid Replacement

Place ample supplies of liquids close to the work area. Preferred drinks are low-sodium, non-carbonated, non-alcoholic, and non-caffeinated. They should be provided at 50°‑ 60°F. Because the normal thirst mechanism does not ensure sufficient fluid intake, encourage workers to drink small amounts on a frequent basis, e.g., one 4-ounce to 6-ounce cup every 20 minutes. The taste of commercially available balanced electrolyte replacement drinks may also encourage fluid intake. (These products are perfectly acceptable when diluted 50% in water.) Although some commercial electrolytereplacement drinks contain salt, this is not necessary for acclimated individuals who generally add enough salt in their diets.

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Administrative and Work Practice Control

• Acclimation

Most people get used to heat exposure up to a point. This is called acclimation and it results in less cardiovascular demand for a given activity. The worker will sweat more efficiently (increasing evaporative cooling) and may lose less salt, thus will more easily maintain normal body temperature. Acclimation decreases the risk of heat‑related illnesses and associated unsafe acts.

Deliberate acclimation involves exposing employees to work in a hot environment for progressively longer periods. For workers with recent experience (within two weeks) in jobs where heat levels may produce heat stress, NIOSH recommends the following regimen: 50% of normal exposure on day one, 60% on day two, 80% on day three, and 100% percent on day four. For new workers who will be similarly exposed, the regimen should be 20% on day one, with a 20% increase in exposure each additional day.

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Administrative and Work Practice Control

• Work/Rest Cycles

Prescribed periods of work and rest are based on specific heat indices and workload estimates (e.g., ACGIH-TLVs). These prescribed levels are based on the assumption that the work is repetitive, controlled, and continuous over an eight-hour shift, and that the rest area is in an environment similar to that in which the exposure occurs.

• Recovery Times

Recovery may be required for any heat stress exposure. Recovery is complete when the person's physiological state has returned to its pre-exposure condition. This means that excess (stored) body heat has been dissipated, lost fluid has been replaced, and electrolytes are in balance. To permit dissipation of stored body heat, the recommended recovery area should be subjectively cool.

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Administrative and Work Practice Control

• Buddy System

Working in pairs or small teams allows appropriately trained workers to observe each other for signs of heat-related disorders. Employees may also share work activities to reduce metabolic heat production.

• Personal Monitoring

An individual's physiological response to heat stress can be monitored with a variety of instruments available on the market. The instruments measure skin or ear canal temperature as a surrogate for core body temperature. Some instruments also measure heart and respiration rates. Unfortunately, there is limited consensus in the scientific community on how to interpret the results.

Most individuals can be trained to monitor their own heart rate. Healthy, acclimated workers should avoid prolonged work/environment combinations that cause their heart rate to exceed the recommended maximum heart rate, MHR when taken during the first minute of rest. (MHRs appear in the table below.) The heart rate should drop to 110-120 beats per minute following the first minute of rest.

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Administrative and Work Practice Control

• Check Times

A prescribed check time (CT) schedule can augment self-determination. Check times are intervals at which a heat stress-trained supervisor or observer (including a co-worker or "buddy") must seek explicit confirmation from individual heat stress-trained workers that each can continue work. That is, the observer determines if there are obvious symptoms of heat disorders, or if there is any sense of diminished capacity. If so, the exposure is terminated and rest is required. Using CTs requires each worker, at regular intervals, to explicitly assess his/her physiological state and ability to continue work, rather than waiting for symptoms to appear.

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Administrative and Work Practice Control

• Self-Determination

Appropriately trained workers can help monitor their own heat condition. Training should emphasize that heat stress can affect an individual's ability to reason clearly. This may cause them to fail to recognize signs and symptoms of heat stress. For this reason, self-determination must be augmented by the heat awareness program, worker training program, and check time and buddy system controls described in these guidelines.

• Other Administrative Controls

Reduce the physical demands of work (such as excessive lifting or digging) by using powered equipment, increase the number of workers assigned to a task, use relief workers, and limit worker occupancy in confined areas.

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Heat Awareness Condition

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• A "Heat Awareness Condition" is declared when the potential for heat stress is significant.
• The "Condition" is based on the daily weather forecast of the National Weather Service (NWS) or other competent forecast. (Use the table below to compute NWS values.) If extremely hot weather is predicted for the next day or days, a "Heat Awareness Condition" is declared to ensure that all aspects of this procedure are in place, and that personnel awareness is heightened. Extremely hot weather is defined here as any of the following:
• Ambient temperature in excess of 95° F (=35° C)

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Heat Awareness Condition

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• NWS apparent temperature (AT), or heat index (HI) in excess of 90° F (=32° C)
• A "Heat Awareness Condition" may exist at many project sites throughout the summer. During a "Heat Awareness Condition", the hazards and controls of heat are continuously emphasized with each employee and supervisor during TSTI. Workers should be instructed to interrupt heat exposure before they feel excessive discomfort or symptoms of any heat-related disorder.
• The "Heat Awareness Condition" is based on publicly available values that makes the program understandable to most employees. It also makes the program more practical at projects with limited access to WBGT monitoring equipment. Some projects advertise a "Heat Awareness Condition" by posting the predicted heat index at the front gate on a sign in the shape of a thermometer.

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General Precautions

DW-HSE-TM035

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Hydrations

The best way to avoid heat strokes and other heat disorders is to keep your body well hydrated. Drink a lot of water if you are exercising or working in hot conditions. Doctors usually recommend consuming eight or more glasses of water per day.

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Ventilation

Remain in cool areas where your body can cool itself. If working in hot conditions, try to take a break to regain energy and to avoid overexposure to the sun’s rays.

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Clothing

What you wear plays a big factor in how your body will handle the heat. Light clothing and loose fitting clothing will help your body in breathing and cooling itself naturally. It is fine to wear a hat or cap to shield yourself from the sun but once you feel warm, remove it. This usually traps the heat inside your body.

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Limit yourself

It is also important to watch the amount of activities you are participating in during hot days. Don’t overdo it. Heat stroke and other disorders can take affect in less than an hour. If you feel yourself get warm and suffocated with the heat, it’s best to take time out and rest in a shady area.

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Desert conditions

In desert environments one may not be aware that they are

perspiring due to rapid evaporation.

Warning!

• You need to learn to drink, even when you are not thirsty.

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• By the time you feel thirsty you are already 10% dehydrated

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• Urine colour gives indication of hydration state ie,� (if urine is dark drink more)

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DW-HSE-TM035

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The color of Urine tells you how dehydrated you are!

Extremely Dehydrated

Drink Water Immediately

Mildly Dehydrated

Drink More Water

Not Dehydrated

HYDRA CHECK -

NOTE: This is a general guide only and in no way replaces medical advice. Not applicable for person taking medicine and supplemental vitamins.

Prevention

• Start drinking water� ( before you start work),
• Drink water� ( As much as you need),
• Check your Urine colour� (note the urine color),
• Ensure adequate ventilation,
• Rotate work� ( from hot to cool areas),
• Report to your Supervisor or the Nurse at first sign of any problem,
• Keep an eye on� your work mates

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Remember!

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