 Thermoregulation  Heat gain, storage and loss  Heat strain and related illnesses  Risk factors for heat strain  Risk assessment and control

“reaksi fisik dan fisiologi tenaga kerja terhadap temperatur sekitar lingkungan yang berada diluar zone nyaman manusia (pekerja)”

Zone nyaman pekerja didasarkan pada standar: - ASHRAE –American Society of Refrigeration, Heating, and Air-Conditioning Engineers. - ASHRAE standard outlines human comfort zones based on temperature and humidity.

Kesetimbangan Panas External Heat Source Cooling Internal Heat Source (Muscular Activity) H

Normal body temperature Kondisi optimal tubuh manusia akan mempertahankan suhu tubuh 37°C

Temperature Regulation is a “balancing act”

- Proses dimana tubuh beradaptasi pada variasi suhu dilingkungan sekitar.  Proses ini akan berlangsung selama kurang lebih 3 minggu  Menurunnya berat badan 1.5% karena dehydration

Hypothalamus – organ utama di otak yang mengatur/menyesuaikan suhu tubuh dengan mengendalikan hormons, dengan cara: - Meningkatkan denyut jantung - Berkeringat - Meningkatnya aliran darah di permukaan kulit

Aliran darah akan mendinginkan permukaan tubuh dari panas yang berlebihan melalui permukaan kulit.

Ada 4 cara pelepasan panas: Convection Radiation Evaporation Conduction

 Internal dan eksternal  70-80% kerja otot - metabolic heat

 Perpindahan panas melalui udara Hot air rising Air cooling Cool air descending

Radiation aliran energi dari sebuah sumber ke lingkungan sekeliling/sekitar.

Proses perubahan cairan menjadi gas. Keringat berubah menjadi upa air. Sweat droplet Sweat vapor

Proses dimana energi dipindahkan melalui kontak langsung. HotCold

Heat Rash (prickly heat):  Sebab: tersumbatnya pori-pori dan saluran keringat.  Gejala: kulit memerah, gatal, nyeri dan iritasi.  First Aid: Menjaga kebersihan, mengeringkan keringat, pakaian longgar, konsult ke dokter bila sakit berlanjut.  Seriousness: Ringan/Relatively minor.

Radiation Burns (Sunburn)  Cause: radiasi UV yg diserap kulit.  Symptoms: kulit mengering, lebam, kerusakan jaringan kulit.  First Aid: Menutup kulit yang terkena, menggunakan krim anti UV (sunscreen). Membungkus bagian kulit yang terbakar.  Seriousness: Minor to relatively serious.

Transient Heat Fatigue:  Cause: kehilangan cairan yang mengurangi sirkulasi.  Symptoms: Kelelahan umum (tiredness or fatigue)  First Aid: Memperbanyak minuman dan beristirahat.  Seriousness: Dampak singkat.

Heat Syncope:  Cause: mengumpulnya darah kebagian extremities bawah dan menyebabkan berkurangnya supply darah ke otak.  Symptoms: Syncope berarti “pingsan”  First Aid: korban ditidurkan terlentang dengan kaki dinaikkan horisontal. Bila sadar diberikan minuman.  Seriousness: Korban butuh satu/dua hari untuk sembuh, hingga mampu beraklimatisasi.

Heat Cramps:  Cause: hilangnnya cairan elektrolit dalam darah menyebabkan kram pada otot.  Symptoms: Otot cramp, bagian anggota badan dan perut.  First Aid: Minum cairan elektrolit dan istirahat.  Seriousness: membutuhkan istirahat.

Heat Exhaustion: Cause: Kurangnya cairan seluruh tubuh membuat dilatasi pembuluh darah berlebihan. Symptoms: Mual, pusing, lemah, sakit kepala, kabur pandangan, profuse sweating, cold/wet (clammy) grayish skin, tidak sadar, coma dan meninggal.

Heat Exhaustion (continued) : First Aid: pertolongan ditempat yang dingin, a face down position, minuman, segera dibawa ke unit UGD. Seriousness: Sangat serius

Heat Stroke:  Cause: Kerusakan pada sytem pengaturan panas tubuh (hypothalamus), fails and sweating stops.  Symptoms: dingin, gelisah tidak bisa istirahat, irritasi, muka merah, disorientation, hot/dry skin (not always), collapse, unconsciousness, kejang and death.

Heat Stroke (continued) :  First Aid: segera dibawa ke UGD.  Seriousness: Heat Stroke is a MEDICAL EMERGENCY.

Indirect Heat-Related Health Effects: Menurunkan kinerja Potensi kecelakaan Masalah Reproduksi Heart/Lung Strain

Predisposing Factors:  very small body size  poor nutrition  overweight  over 40 years old (the older the more sensitive)  previous heat illness  heart disease  high blood pressure  diabetes  skin disease  liver, kidney, and lung problems

Predisposing Factors, cont’d:  physical activity  poor physical condition  fatigue  excessive clothing  dehydration  being female  being pregnant  alcohol, caffeine, nicotine intake  Sunbathing

Drugs that interfere with body’s thermo- regulation: Heat production:  thyroid hormone  amphetamines  TCA’s  LSD Decrease thirst:  Haldol Decrease sweating:  antihistamines  anticholinergics  phenothiazines  Benztropine

 Accurate temperature measurement is crucial for determining thermal stress.  WBGT (Wet Bulb Globe Temperature) is the accepted method for determining true temperature  Accounts for air currents, relative humidity, solar load

Heat Stress Monitor takes readings from, and calculates WGBT by: -Dry Bulb Thermometer -Wet Bulb Thermometer -Globe Temperature

For indoor or shaded environments: WBGT = 0.7 x T nwb x T g T nwb = natural wet-bulb temperature T g = globe temperature For direct sunlight exposure: WBGT = 0.7 x T nwb x T g x T db T db = dry-bulb temperature

Using the reading from the thermostat on the west wall, convert that temperature to WBGT using the following info: -WB = 64.1 F -GT = Temperature reading from thermostat

Step 1 : Convert F temps to C -5/9 (temp F) –32 = temp C *5/9 (64F) –32 = 17.77C *5/9 (thermostat F) –32 = ?

WBGT = 0.7 x WB x GT WBGT = ? WBGT =

Verification of readings : Using WB temp and WBGT from monitor, calculate the corresponding GT, which should agree with the thermostat…if it’s accurate. * GT = (WBGT – 0.7(WB))/0.3 * convert temp to F - 9/5(Temp C) + 32 = Temp F

 WBGT is used by Industrial Hygienists to determine the workload requirements/restrictions for work areas, using Heat Stress/Strain TLV.

Engineering controls Administrative controls Personal protective equipment

- Use machinery instead of people where applicable - Take steps to cool building or worksite - Use thermal barriers (mylar reflective surfaces) - More?

-Conduct training on Heat stress/strain -Work during coolest part of day -Co-worker observation -Implement work/rest schedule -More?

-Drinking adequate amounts of fluids -Protective clothing (light colors reflect heat) -Protective equipment (vests, fans) -More?

Cooling vest

How Much Water is Enough?  More than you want just to satisfy your thirst  Sources of water are: 1. Fluids - 1 cup or 8 oz = 240 mL every 20 min 2. Foods - fruit & veggies are 90% water  Why 10-15°C? … to maximize the amount you drink (not too cold, not luke warm)  Does it need to be delivered to the work station? … depends on workplace logistics …

What to drink:  Electrolyte drinks (e.g. Gatorade) are usually not needed for typical North American diet (can be used for first aid).  Stay away from caffeinated, carbonated, diet drinks, and alcohol as they take water out of your body.  Water is the best; juices and/or no caffeine sport drinks are also good (juices contain energy restoring glucose).

% weight loss fluid loss time*effect & symptoms (* timing may vary based on intensity of work and heat/humidity) 1%0.75 L1 hr unnoticed (at 1.5% weight loss you are considered dehydrated) 2%1.5 L2-3 hrs loss of endurance, start to feel thirsty, feel hot, uncomfortable 3%2.25 L3-4 hrs loss of strength, loss of energy, moderate discomfort 4%3 L4-5 hrs cramps, headaches, extreme discomfort 5-6%3.5-4 L5-6 hrs heat exhaustion, nausea, faint 7+%5+ L7+ hrs heat stroke, collapse, unconsciousness

Fans:  Purpose of a cooling fan is primarily to increase the rate of sweat evaporation but it also cools by convection if the air is cooler than the skin  Fan coolers may interfere with local exhaust ventilation for contaminant control, therefore be careful in where they are placed

Fans, cont’d:  The lower the relative humidity the better the evaporation the more effective the cooling  If the relative humidity is close to 100% the fan will no longer increase evaporation of sweat  The closer the air temperature is to skin temperature (35-36°C) the less effective the cooling  if the air temperature exceeds skin temperature then the fan may even heat up the body (like a convection oven)!

 Notice the ACGIH Heat Stress/Strain TLV’s take into account the workload as well as the work/rest cycle.  Also to note that the TLV’s make a few assumptions regarding acclimatization, clothing, water and salt intake, as well as the ability of most workers to work continuously at 38C.

 Light: standing with light work at machine/bench using mostly arms; using table saw  Moderate: walking about with moderate lifting or pushing; scrubbing in a standing position  Heavy: shoveling dry sand; cutting with a hand saw  Very Heavy: shoveling wet sand

The following correction factors for the WBGT should be used:

work demands:lightmoderateheavyvery heavy 100% work; (breaks incl.) not allowed 75% work; 25% rest not allowed 50% work; 50% rest % work; 75% rest AcclimatizedUnacclimatized

 Heat Stress/Strain measurements (WBGT) should be taken prior to work being performed, to allow for measures to be taken to protect exposed individuals.  Anticipated workload, work/rest cycle, clothing should be taken into account in determination.  If work/rest cycle is not constant, time- weighted average should be used in determination.

Take readings:  Select a representative spot to place your thermometer(s) and/or hygrometer  Designate someone to take readings on an hourly basis (on the hour) and record them  If activities are altered in response to the heat (slow down, more breaks, water distribution) record the details including the time and the degree  If heat stress health conditions appear record time and describe symptoms and situation

Things you can check:  Look for typical heat strain symptoms; feeling over-heated, fatigue, headache, nausea, weakness, dark concentrated urine, etc.  Sweat that drips off your body no longer allows for cooling by evaporation; thus, unless there’s another medical reason for it, this is a sign that your body is heating up  Check your pulse; heat stress is unlikely if your pulse rate is under 100 beats per minute after 1 minute rest.

 Just as high temperatures have far- reaching effects on the body, cold temperatures present their own challenges to the thermal regulation of the human body.  Let’s examine what the effects of cold temperatures are, what health effects cold temperatures present, and methods for treatment of cold-related injuries.

 As we see, the four causes of heat loss in a hypothermic environment are convection, radiation, evaporation, and conduction.  The large difference is that in hypothermic environments, you are trying to retain heat, instead of releasing it to the environment.

Determining the risk of cold-injuries is done using the following formula: Heat Retention + Heat Production > Cold Factors or Heat Retention + Heat Production < Cold Factors

- Heat Retention: - Size/shape (Eskimo vs. Masai) - Insulation (Clothing type/# of layers) - Fat (Used as insulation) - Shell (Blood in core of body) These are positive factors. Increase of any or all of these factors decreases risk of injury.

- Heat Production - Activity level - Shivering response - * Limited by: - Fitness level - Nutrition - Fluid intake

- Cold Factors: - Temperature - Humidity - Wind The total of these represents the challenge to the thermo-regulation of the human body. If Retention + Production < Cold Factors, Hypothermic condition could develop.

 “a decrease in the core body temperature to a level at which normal muscular and neurological functions are impaired” – Medicine for Mountaineers  Hypothermia is possible at any temperature under 98.6 degrees, if the right conditions exist (lack of insulation, increased heat loss, etc.)

“Umbles” – Stumbles, Mumbles, Fumbles, and Grumbles  Shows decreased physical and mental capacity.

Mild Hypothermia: - core temperature 98.6 – 96 F - non-voluntary shivering -complex motor functions impossible -vasoconstriction to periphery

Moderate Hypothermia: - core temperature 95 – 93 F - loss of fine motor coordination - slurred speech - violent shivering - paradoxical undressing - apathetic attitude

Severe Hypothermia: - core temperature 92 – 86 F or below - shivering in waves (violent then pause) - person curled in fetal position to conserve heat - muscle rigidity develops - pale skin/dilated pupils - reduced pulse

-at 90 degrees F, the person goes into hibernation, slowing heart rate and respiration, shunting blood to peripheral tissues. -at 86 degrees F or below, the person looks dead, but is still alive…barely. Severe Hypothermia is LIFE THREATENING!

Although hypothermia is well known, there are other cold injuries. -Frostnip -Frostbite -Immersion foot (trench foot)

Frostnip is the freezing of upper layers of the skin. Characterized by: - white, waxy skin. - general numbness Frostnip is generally reversible and does no major tissue damage.

Gently warm area by blowing warm air on it or by placing it near a warm body part. DO NOT rub the area! Rubbing can rupture frozen cells, causing extensive damage. Frostnip is a warning sign of possible frostbite*

Frostbite is a freezing of the surface and deep layers of tissue. Characterized by: - white, and feels “woody” - numbness, possible anesthesia - deep frostbite can affect bone and muscle - purple/black color is from ruptured blood vessels

 Immerse affected area in 105 – 110 degree F water until thawing is complete. - part will be extremely painful  Wrap affected part in sterile gauze  Affected part should not be used for anything - keep part from refreezing

Immersion foot is caused by prolonged exposure of the feet to wet, cool conditions. Characterized by: - yellowish, smelly feet - possibly numb - sloughing of skin tissue/itching *Immersion foot may cause permanent damage to foot tissues, leaving person susceptible to cold injuries in future.

- Careful washing and drying of feet. - Keep feet dry as much as possible. - Keep off feet as much as possible until healed.

TERIMA KASIH