Heat Stress in the Workplace

Jeannette Combes, OHN Canada Bread Atlantic Region Occupational HealthAtlantic Region, Occupational Health Nurses Association of Nova Scotia

www.ohnans.com

March 27, 2008; The Nova Scotia Safety Conference, “The New Culture of Safety”

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Acknowledgements

Dr Barbara Keddy RN PHD – Information on yMenopauseDr Donald Haig – Lifemark Columbia Health –i f ti R t t W k d C St diinformation on Return to Work and Case Studies.John Oudyk – CIH, ROH, Occupational Hygienist, Occupational Health Clinic for Ontario Workers IncOccupational Health Clinic for Ontario Workers Inc

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Learning Objectives

Why worry about Heat Stress?Discuss some external heat source controls.Health Effects of Heat StressDiscuss Pre-disposing factors to heat stressDiscuss Pre-disposing factors to heat stressWho is typically vulnerable. to heat stress illnesses.Heat exhaustion, heat stress, heat syncopy, prickly heat, heat strokestroke.Monitoring the workplace

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Why Worry about Heat Stress?

Heat can kill!Heat can kill!Work-related heat stroke fatalities: 1990 t d t d d ll ti1990: student, second day collecting

garbage2001: bakery worker in Barrie

If global warming is happening, heat stress will become more important

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stress will become more important

Hurricane Mitch over the Caribbean 1998, (Health Effects of Climate Change, Environmental Health Effects Perspectives, April 2007)

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Desertification in Hebei Province, China 2000 (ref: Health Effects of Climate Change, Environmental Health Effects Perspectives, April 2007)

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External Heat Source Controls

At the sourceReplace/isolate heat producing processesBlock radiant heat with barriers (shade)

Along the pathAlong the pathIsolate worker from heatAir condition workplace (booth)Capture hot air with exhaust ventilationCapture hot air with exhaust ventilation

External Heat sources

hot weather

radiant heat sources - Ovens

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Internal source controls:

At the source HReduce workload

improve ergonomics, provide assistance, increase relief time

Internal

H t Hincrease relief timeslow down

Provide adequate waterActively cool body

Heat sources

muscle activity

H

Gradually acclimatizeEnsure good nutrition and rest

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Promote Cooling

Wear loose clothes that allow sweat to evaporate easily (cotton)

Take internal heat sources into S

S

Coolingaccount when using any personal protective clothing that prevents sweat from evaporating

Sg

evaporationof sweat

evaporating

Wash clothes regularly and maintain good personal hygiene

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CoolingHeat H

S S

Cooling- evaporation- radiation

Heat Balance

H

S S - convection- conductionHH

External

Internal

Heat sources- radiation

convection InternalHeat sources- basal metabolism

- convection- conduction

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basal metabolism- activitymuscle activity

Transient Heat Fatigue:

Symptoms: General feeling of tiredness or fatigue.

First Aid: Fluid replacement and restand rest.

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Heat Rash (prickly heat)

Symptoms: Skin becomes reddened and may itch, feel prickly or hurt.

First Aid: Practice good personal hygiene; keep the skin clean and the pores unclogged, allow skin to dry, wear loose clothing, see doctor if rashloose clothing, see doctor if rash persists.

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Symptoms: Syncope means “fainting ” First

Heat Syncope (fainting) Symptoms: Syncope means “fainting.” First

signs are dizziness, feeling light-headed and perhaps nauseous, then the person may faint. Usually occurs in the beginning of heat stress season before the circ lation

(fainting)

heat stress season before the circulation system is adapted.

First Aid: Lay victim in a cool location yhorizontally with feet elevated. If conscious, give fluids. Treatment the same as shock.

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Heat Cramps:Symptoms: Cramping of either active

l ( l ) i l t

Heat Cramps:

muscles (arms, legs) or involuntary (usually abdominal) muscles (or both).

First Aid: Replenish electrolytes through drinking of fluids such as Gator-Ade, Squincher, PowerAde, etc-Ade. Rest in a

l i tcool environment.

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Heat Exhaustion:

Symptoms: Nausea, dizziness, weakness headache, blurred vision, profuse

ti ld/ t ( l ) i h kisweating, cold/wet (clammy) grayish skin, unconsciousness, coma and death.

First Aid: Place victim in a face down position in a cool location administerposition in a cool location, administer fluids if the victim is conscious. If unconscious, seek medical care or transport to a medical emergency room.

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Heat Stroke

Life threatening medical emergencyLife threatening medical emergency resulting from failure of the body’s normal thermoregulatory mechanismsnormal thermoregulatory mechanisms resulting in elevation of body temperature to extreme levels usuallytemperature to extreme levels usually greater the (41C) producing multisystem tissue damage and organmultisystem tissue damage and organ dysfunction.

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Heat Stroke:Heat Stroke:

Symptoms: Chills, restlessness, irritability, euphoria, red face and skin, disorientation, hot/dry skin (not always), collapse, unconsciousness, convulsions and death.unconsciousness, convulsions and death.

First Aid: Immediate, aggressive cooling of the victim’s body using wet cloths, immersion y g ,into cold water or alcohol wipes. Transportto emergency medical facility ASAP!

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Heat Stroke Treatment

Secure the airwayyRemove patient’s clothingMonitor temp with rectal probe and Urinary Output with FoleyImmediate cooling with evaporative methods or immersion (stop when body temp reaches <102 2 F)immersion (stop when body temp reaches <102.2 F) Administer oxygenAdminister IVF with D5 1/2 NS or D5NS, or LR,Check glucoseCBC, Lytes BUN Creatine, lactate, coags, DIC, urinalysis

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Heat Stroke – Lab Findings

decreased Na, K, Ca, and Consumption coagulopathyPO4Increased BUNHyperuricemia

Concentrated urineDehydrationproteinuriayp

Lactic acidosisLeukocytosisHemoconcentration

Tubular castsMyoglobinuriaElevated AMIP

HemoconcentrationThrombocytopeniaFibrinolysis

EKG changes*** Elevated AST/ALT ***

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Development of Heat Strokehttp://www.ttuhsc.edu/SOM/physiology/Pressley/Course/S_Shock.GIF

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Pathophysiology

Specific cellular mechanism underlying the failure of p y gthermoregulatory homeostasis is not completely understood.P l d h t t d i ifi tProlonged heat stress produces significant increases in peripheral vasodilation as skin blood vessels dilate in an attempt to dissipate heat eventually producing a reduction of the thermal gradient between the core and the skin.As severe heat stress continues the cutaneousAs severe heat stress continues, the cutaneous blood flow decreases and failure to perfuse the skin with heated blood from the core results in

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dramatically increased rate of heat storage.

Classic Heat Stroke

Victims are usually aged, often bedridden, persons confined to poorly ventilated homes without air conditioning during summer heat waves

465 deaths in Chicago 1995 certified as heat relatedVictims of Classic Heat Stroke commonly suffer from chronic diseases, alcoholism, or mental illness that predispose to heat illness.Patients are often taking anticholinergics, antiparkinsonian drugs, or diuretics that impair the ability to tolerate heat stress and therefore increase risk.

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Watch out for each other!

A worker heading into a heat gstroke will no longer realize what’s happening to him/her

It is vital that co-workers be able to recognize what’s happeningto recognize what s happening and intervene

Without quick attention, the co-worker may die!

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Indirect Health Effects:Indirect Health Effects:

Reduced Work Performance: tired, fatigued workers perform with d d ffi ireduced accuracy, efficiency

Increased Accidents: tired, fatigued workers are more susceptible t id t d i jto accident and injury

Reproductive Problems: heat has been shown to reduce both male and female fertility and can be a problem for the fetusand female fertility and can be a problem for the fetus

Heart/Lung Strain: if you already have heart, lung, kidney or circulatory problems; heat stress is an added strain on yourcirculatory problems; heat stress is an added strain on your body which in severe situation may precipitate serious episodes of acute problems

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P di i F tPredisposing Factors:

very small body sizeoverweight

40 ld (th ld th iti )over 40 years old (the older the more sensitive)previous heat illnessheart diseasehigh blood pressurediabetesinactivityinactivityphysical activity

l t ’ ll l bl

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…sooner or later we’re all vulnerable …

… with all these vulnerabilities who typically gets heat stroke?typically gets heat stroke?

young physically fit y g p y ymalesand sick older people

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What’s the Law? (May vary from province to province)

General Duty Clause:25(2)(h) “… an employer shall, … take every precaution reasonable in the

f fcircumstances for the protection of a worker;” taken from: OH&S Act

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Screening WBGT (in °C ):

work demands: light moderate heavy very heavy

100% work; (breaks incl.)

29.527.5

27.525.0

26.022.5

not allowed

75% work; 25% rest 30.529.0

28.526.5

27.524.5

not allowed

50% work; 50% rest 31.530 0

29.528 0

28.526 5

27.525 030.0 28.0 26.5 25.0

25% work; 75% rest 32.531.0

31.029.0

30.028.0

29.526.5

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AcclimatizedUnacclimatized

TLV® Clothing Criteria:Requires a penalty be added to the WBGT measurement (do not

dd t th t d d!) f t i t f l thi hi h hi d thadd to the standard!) for certain types of clothing which hinder the evaporation of sweat:

clothing type: add to measurement

summer work clothes 0°C

cloth (woven material) overalls +3.5°C WBGT (~ +5° to +7°C Humidex)( +5 to +7 C Humidex)

double-cloth overalls +5°C WBGT (~ +7° to +10°C Humidex)

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Cl thi IClothing Issues:

Thomas Bernhard, has done research on specific types of clothing and calculated exact clothing factors

He appears to use the 50th percentile for his correction factors whereas the TLV appears to

hpp

use the 95th percentile

thus, for cotton overalls, his recommendations is , ,around 2°C WBGT correction factor instead of the 3.5°C WBGT correction factor cited in the TLV

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When are you acclimatized?When are you acclimatized?acclimatization requires up to 3 weeks to be fully established and is

ti bl d d ft 4 dnoticeably decreased after 4 days: the TLV® documentation suggests as a criteria: exposed for 5 of last 7 daysreviewing the Jun-Sept/01 weather data for Toronto there were only 2 dayswhich satisfied this criterion (Aug 8 & 9/01)( g )“Hot spells in Ontario seldom last long enough to allow acclimatization.”

(taken from Ontario Ministry of Labour Heat Stress Guideline: http://www.gov.on.ca/LAB/english/hs/guidelines/gl_heat.html)

Dr Bernard is of the opinion that all workers in Ontario are acclimatizedDr. Bernard is of the opinion that all workers in Ontario are acclimatized once you’re into the summer

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Acclimatized version:Humidex1 Response Humidex2

25-29°C supply water to workers on an “as needed” basis 30-33°C

post Heat Stress Alert notice; 30-33°C encourage workers to drink extra water;

start recording hourly temperature and relative humidity 34-37°C

34-37°Cpost Heat Stress Warning notice; notify workers that they need to drink extra water; ensure workers are t i d t i t

38-41°Ctrained to recognize symptoms

38-39°C

provide 15 minutes relief per hour; provide adequate cool (10-15°C ) water; at least 1 cup (240 mL) of water every 20 minutesworker with symptoms should seek medical attention

42-43°C

40-42°C provide 30 minutes relief per hour in addition to the provisions listed previously; 44-45°C

43-44°C if feasible provide 45 minutes relief per hour in addition to the provisions listed above 46-48°Cabove.

45°C or over

only medically supervised work can continue49°C

or over

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Workload Categories:

At the detailed analysis stage the TLV® requires detailed time-weighted average calculations of the workload:

activity level category: workload (kcal/hr)light up to 249light up to 249moderate 249-343heavy 343-447

very heavy 447+

• It is important to note that the heat stress TLV® is based on data collected from army

it ( i ht 154 lb 20 ld)

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recruits (average weight 154 lbs., 20 yrs old)

Workload Adjustments:

Dr. Bernard is convinced there is enough of a safety factor in the TLV to handle differences in age & weight

NIOSH Heat Stress Documentation actually gives anNIOSH Heat Stress Documentation actually gives an example of weight correction

Ergonomists tell us you need to take age, fitness and sexErgonomists tell us you need to take age, fitness and sex into account when evaluating metabolic demands

Issues such as dehydration, medications, medical conditions and pregnancy are also of concern to theconditions and pregnancy are also of concern to the workforce

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Problems with using the TLV:1. Most workplaces don’t have WBGT meters (expensive) and even those that do

can’t be at all places at oncecan t be at all places at once

2. Reading the tables is confusing; calculating the metabolic rates and time-weighted averages gets quite complicated

3. Adjusting metabolic rates for weight and age puts attention on the individual instead of the work environment and makes it an individual evaluation

4. The WBGT appears to downplay heat stress (e.g. @ 38.7°C and 25% RH the WBGT is 28 0°C (75% rest starting point))WBGT is 28.0 C (75% rest starting point))

5. It is much easier to manage heat stress on a group basis as opposed to dealing with individuals in the same group differently. Talk to your workers.

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August 9 2001: Kim Douglas Warner DiedAugust 9, 2001: Kim Douglas Warner Died of Heat Stroke

di t E i t C d A t 9 2001 tdaccording to Environment Canada on August 9, 2001 outdoor temperature in Barrie is 33.4°C, and humidity was 30%; so the outdoor humidex was 36°C and the outdoor WBGT was 24.8°C Passed away Monday Night. Age 44.

if temperature in the bakery was estimated to be 52°C and if the humidity inside was 10%, then Humidex would have been 54°C for the workplace (33°C WBGT)workplace (33°C WBGT)

http://www.labournet.net/world/0108/bakery1.html

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CAW Request

Kim Warner Douglas was a CAW membersoon after the incident, the CAW approached OHCOW to find a simpler way of evaluating heat stress than the WBGT (Humidex?)the Oshawa GM assembly plant was used as the “guinea pig”GM management had input into the developmentHumidex plan promoted among unions and implemented in numerous workplaces

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How do we convertHow do we convert WBGT to Humidex?

1 use moderate unacclimatized WBGT category as1. use moderate unacclimatized WBGT category as the basis the warning and activity restrictions

h li ti d t th b i f2. use heavy unacclimatized category as the basis for the alert and program initiation

3. correlated Humidex with WBGT using calculator based on a formula correlating WBGT with dry bulb & wet bulb measurements (i.e. humidity)

4. looked for workplaces to collect data in for the summer of 2002 to check WBGT to Humidex t l ti

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translation

H id R PlHumidex Response Plan:Humidex action

30-33 alert & information & water34-37 warning, education & double water

restrict activity 25% & actively monitor for signs of38-39 restrict activity 25% & actively monitor for signs of heat strain

40-42 restrict activity 50% & actively monitor for signs of heat strainheat strain

43-44restrict activity 75% & actively monitor for signs of heat strain

45+ stop work

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Humidex Days (Apr 15 Oct 5/02):(Apr 15-Oct 5/02):

Humidex (% work) Toronto Island Buttonville

30-33(100%)32 28

34-37(100%)20 28

38-39(75%)13 7

38-39(75%)

40-42(50%)4 5

43-44(25%)1 2

45+0 0

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45+(0%)

Heat stress death 1990 - Inquest Findings:

Brian Freeman, arts student, on the second day on a summer job as a garbage collector experienced a heat t k di d 17 d l tstroke; died 17 days later

No training to recognize symptomsWBGT too difficult to apply and doesn’t take into account vulnerabilitiesvulnerabilitiesRather than relying on the TLV, train workers to enable them to self-regulate (recognize symptoms and know how to reduce heat stress with breaks and fluid intake)to reduce heat stress with breaks and fluid intake)Have medical history done by your OHN annually and identify workers at risk. Some may not know they are at risk.issues around malignant hyperthermia, a genetic condition (1 in 200) which makes people more susceptible to heat strain

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“Managing” the Problem?Managing the Problem?

varied approach even within the same union and same employervaried approach even within the same union and same employersome collective agreements have temperature or Humidex criteria spelled out (e.g. an auto parts manufacturing plant in Kitchener had 34°C Humidex shutdown - but not anymore … )others use the ACGIH TLV® and take WBGT measurements (spot measurements, fixed location - area, personal - very few as per TLV®

documentation)others simply “manage” their way through the situationothers simply manage their way through the situation

IF IT WORKS … GREAT!A Few Practical Issues ………

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Medical Activities

Appropriate Medical Activitiespp pEducate Heat exposed workers in collaboration with Safety and IH (?union)Pre-assignment and Periodic ScreeningReturn to WorksEmergencies with First Aiders (Training andEmergencies with First Aiders (Training and Intervention)On site Medical Screening (RN with protocol + MD g ( pfollow up)

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Why Medical Controls

For Heat Stress specifically:p yEarly detection “safety net” example: ALCAN (350 middle aged+

workers, 45% personal risk factors, 8-12 near misses per summer, no acute cases)

ACGIH applies to 95% of health young acclimatized reasonably dressed, well hydrated males. KINDAreasonably dressed, well hydrated males. KINDA HARD TO FIND…Olympic Track Team!

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Education

Awareness/Vigilance is an important Safety Tool especially for an acute aggressor. Important activity of Safety Program.

“What (IH), So What (MD), Now What (Manager/Safety Rep)”( ), ( ), ( g y p)

Yearly sessions of 1-2 hours given to small “natural” work groups. Based on info in their own work environment. Repeated as needed to update IH/surveillance info, if increased risk found, or cases detected (near miss), , ( )

Impact is hard to measure. Well accepted. Increased short term knowledge (awareness?vigilance?)

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Drink WaterDrink WaterDrink WaterDrink WaterA li i i d dAcclimatization does not decrease your

body’s need for water.

Drink plenty of water!

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What to drink?

Electrolyte drinks (e.g. Gatorade) are usually not needed for typical North American diet (can be used for first aid fortypical North American diet (can be used for first aid for cramps).

Stay away from caffeinated carbonated diet drinks and alcoholStay away from caffeinated carbonated, diet drinks and alcohol as they take water out of your body.

Water is the best; juices and/or noncaffeine sport drinks areWater is the best; juices and/or noncaffeine sport drinks are also good (juices contain energy restoring glucose).

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DehydrationDehydrationDehydrationDehydration

To prevent dehydration, take advantage oftake advantage of

scheduled water breaks!

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Dehydrationtaken from: OH&S Canada Volume 69, Number 5, page 52, May 2000

fluid loss time* effect & symptoms (* ti i b d i t it f k d h t/h idit )(* timing may vary based on intensity of work and heat/humidity)

0.75 L 1 hr unnoticed (at 1.5% weight loss you are considered d h d t d)dehydrated)

1.5 L 2-3 hrs loss of endurance, start to feel thirsty, feel hot, uncomfortable

2.25 L 3-4 hrs loss of strength, loss of energy, moderate discomfort

3 L 4 5 hrs cramps headaches extreme discomfort3 L 4-5 hrs cramps, headaches, extreme discomfort

3.5-4 L 5-6 hrs heat exhaustion, nausea, faint

5+ L 7+ hrs heat stroke, collapse, unconsciousness

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5+ L 7+ hrs heat stroke, collapse, unconsciousness

H M h W t iHow Much Water is Enough?

More than you want just to satisfy your thirst

Sources of water are:Sources of water are:1. Fluids - 1 cup or 8 oz = 240 mL every 20 min2. Foods - fruit & veggies are 90% water

Why 10-15°C? to maximize the amount you drink (not too cold notWhy 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 …workplace logistics …

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Eat HealthyEat HealthyEat HealthyEat Healthy

You can and should replace essential elements lost during sweating;You can and should replace essential elements lost during sweating;during sweating;

Eat a balanced diet rather than taking salt t bl t d i ki

during sweating;

Eat a balanced diet rather than taking salt t bl t d i kitablets or drinking expensive sports drinks.

tablets or drinking expensive sports drinks.

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Cooler Fans

Purpose of a cooling fan is primarily to increase the rate of p g p ysweat evaporation but it also cools by convection if the air is cooler than the skinFan coolers may interfere with local exhaust ventilation for ycontaminant control, therefore be careful in where they are placed and how they are pointed

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Cooler Fans (li it ti )Cooler Fans (limitations)

If the relative humidity is over 75-80% the fan ywill no longer increase evaporation of sweat

The closer the air temperature is to skin temperature (35-36°C) the less effective the

licoolingif the air temperature exceeds skin temperature then the fan may even heat up the body (like a convection oven)!

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Wear the Gear?

Reference: www. http://www.smh.com.au

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Personal Protective Equipment ?Personal Protective Equipment ?Special cooling vests or ice vestsSpecial cooling vests or ice vests have been developed to wear under chemical–resistant suits?

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IH Controls

IH controls:Fractionate thermal dose by rest work/cycles (see ACGIH handbook)Modify work (metabolic) loadModify work (metabolic) loadA/C rest areas to push down calculated heat loadIce vests, reflective insulated suits, vortex tubes , ,(need compressed air) Hard to calculate impact unless HR/core temp monitoring.

NB: Don’t use synthetics in radiant env. They melt and stick!

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Return to Work

Mainly worried about cardiac and renal disease. Heat can shift CV i 1 2( ) A i H ACV compensation 1-2(rare) American Heart Assoc. classificationAcclimatization is lost after 5-7 daysW t h t f l t h f t illWatch out for convalescent phase of acute illnessNew meds/substance abuse (EtOH, sympatheticomimetics)What to do with pregnant women??Wh t b t / lWhat about pre/ menopausal women.

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Hot Flashes! Power Surges?

Caused by hormonal changes.y g

Affected by lifestyle and medications.

Diminished level of estrogen

Affects the hypothalamus which controls sleep, sex, appetite, body temperature.p

The drop in estrogen confuses the hypothalamus, the ‘thermostat’

And reads “TOO HOT”.

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Tricks to Alleviate Hot Flashes.

First, there are practical things: wear layered clothing, no turtle necks, carry a fan, or wear less to bed if these are night sweats. Sleep and work in a cool room. Avoid hot showers, saunas, hot tubs.Do not wear or sleep on or in wool, synthetics or silk.Second, watch the diet. Avoid foods like spices, caffeine, chocolate, alcohol. Keep ice water on hand.

http://www.ellenedith.com/cartoons/womenswit/wowit_f.jpg

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More tricks to alleviate Hot Flashes

Third, exercise. Many women who exercise regularly appear to have less flashes or night sweats.Fourth, learn to say no!Fifth, inform your colleagues if you suffer from heat., y g ySixth, relaxation and stress reduction techniques, e.g. yoga, massage, tai-chi.

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Emergencies

EmergenciesEmergenciesWork on Emergency Response from the site to the ER (coordinate with local Health providers)Part of general triage system for any worksite critical eventworksite critical eventTrain specifically for Heat Imbalance pathology (start with co-workers)pathology (start with co workers)Rehearse, Rehearse, Rehearse

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Pregnancy

www.speedysigns.com

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Pregnancy Demands

Essentially affects every system in the women’s body and many of those changes are a direct result of major pregnancymany of those changes are a direct result of major pregnancy hormones including estrogen, progesterone, human chorionic gonadotropin, human placental lactogen and relaxin.These hormones are responsible for respiratory, CVS, GI, GU,

l k l t l ki d h i d h h l i l dmusculoskeletal, skin, and hair and physochological and emotional changes.By the end of pregnancy women require 15% to 20% more Oxygen demands of maternal oxygen consumption and fetal yg yg poxygen needs.Short of breathPregnant women who perform physical labor at work should be given extra time to complete their tasksgiven extra time to complete their tasks.

Reference: Littleton, L.Y. & Engebretson, J.C. (2002) Maternal, neonatal and women’s health nursing. Albany, NY Delmar.

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References

1. The U.S. Department of Labour. Occupational Safety & Health Administration. Heat Stress. The OSHA Technical Manual Section III: Chapter 4. Retrieved from the internet at pwww.ohsa.gov June 2006.2. University of Florida, Environmental Health and Safety Finance and Administration. Heat Stress Policy. Retrived from the internet at http://www.ehs.ufl.edu/General/heatstrs.pdf June 20063. Wikipeida, the Free Encyclopedia. Wet Glove Temperature. Retrieved from the internet at

iki di / iki/W t B lb Gl b T t J 2006www.en.wikipedia.org/wiki/Wet_Bulb_Globe_Temperature June 20064. Patty’s Industrial Hygiene & Toxicology. Heat Stress: Its Effects, Measurement & Control. Chapter 21, Vol I, Part A 4th edition.5. Construction Safety Association of Ontario. Heat Stress; Guidelines for recognition, Assessment and Control in Construction. Retrieved from the internet at www.csao.orgJune 2006June 20066. United States Coast Guard. Coast Guard Cutter Heat Stress Program. Retrieved from the internet at www.uscg.mil/ccs/cit/cim/directives/CIM/CIM_6260_17.pdf June 20067. Canadian Centre for Occupational Health and Safety. Hot Environments & Health Effects. Retrieved from the internet at www ccohs ca/oshanswers/phys agents/heat health html June 2006www.ccohs.ca/oshanswers/phys_agents/heat_health.html June 20068. Occupational Health Clinics for Ontario Workers. Humidex Response Plan. Retrieved from the internet at www.hchsa.on.ca/new/OHCOWHumidex/plan.pdf9. Canada Bread Company Limited Heat Stress Program Policy. Issued May 2003, Revised June 2005.

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