Heat Stress Heat Stress: –The amount of heat to which a worker body is exposed to based on external and internal factors: Environmental Factors ( sun, air temperature, humidity & temperature of surrounding ) Body Heat (metabolic)

S S Cooling Conduction Convention Radiation Evaporation Body’s Heat Balance System H H Internal Heat source Muscle activity Digestion Breathing H External Heat source Air temp. Hot surrounding objects

The Body’s Cooling System: Body’s response to heat can be compared to your car’s cooling system Coolant (blood) is circulated by a pump (heart) from hot inner core to a radiator (skin cooled by the evaporation of sweat). When temperature is increased, it can be sensed by thermostat (hypothalamus) coolant flow is redirected by a system of pipes, valves and reservoirs (blood circulation system).

Normal Cooling Mechanism controlled by an organ “hypothalamus” located in the centre of brain sends out hormones which: change heart rate start sweating increase blood flow to the skin When “hypothalamus” work well The core temp drops Hypothalamus regulates homeostatic functions: -body temperature -thirst/urine output -food intake Hypothalamus

Why Cooling Mechanisms Fail? 1.So much sweat is lost that result with; Dehydration The body cannot cool itself by sweating and the core temperature rises 2.Salt loss causes heat cramps 3.So much of the blood flow goes to the skin that other organs cannot function properly

What are the health effects of heat stress?

Heat Cramps Causes This normally happens after hard physical work. Most often to people who aren’t used to the heat, who sweat a lot or don’t drink enough fluids. Symptoms Severe pain and cramps in legs and abdomen, fainting or dizziness, weakness, profuse sweating and headaches. Treatment Stop activity, rest in cool place, drink lots of water or sports beverage Painful muscle cramps, usually in legs or abdomen, warn that heat stress is developing

Heat Exhaustion Causes excessive loss of body fluids and important salts in sweat due to overexposure to high temperatures and humidity. Symptoms Heavy sweating Worker is pale and tired Nausea and vomiting Headache, blurred vision Dizziness and fainting Treatment Get to the shade, cool off, drink lots of water, cold wet towels or ice, fan and elevate legs above heart.

Heat Stroke Symptoms Headache, nausea, dizziness, skin is red, dry and very hot (sweating has ceased). No sweating, Disorientation, unconsciousness, convulsions and death. Causes The body’s temperature regulation mechanism fails and sweating stops. The Core body temperature rises dramatically Heat exhaustion Can progress to Heat stroke Treatment: Remove to cooler location, loosen clothing, immerse in cool water, wrap in wet sheets, cold compresses to the head, neck and groin.

Heat Stroke Heat stroke is a medical emergency and a life threatening condition

who is at risk? People with: Overweight Very small body size Physical condition Lack of heat acclimatization Heart disease, high blood pressure Diabetes

Job Risk factors Factors related to heat stress: Heavy work Extended shifts Heavy clothing PPE and respirators Exposure to any toxic agent Body generates more heat during heavy work

Heat Stress Controls and Management: Cool building/process Reduce job demands Provide fans/ventilation in working area PPE (personal proactive equipment) Awareness Drinking lots of water Encourage drinking (Babylyte / re-hydration drinks)

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