WORKING IN HOT WEATHER Mohawk College by benbenzhou


									WORKING IN HOT WEATHER                                are outside. Depending on the particular
                                                      source and your exposure to it, radiant heat
                                                      can significantly add to the overall heat
AWARENESS &                                           stress burden.
INFORMATION                                           Clothing
Working,      playing     or                          Lightweight summer clothing typically
exercising in the hot,                                consists of pants and a shirt. Additional
muggy days of summer brings the risk of               clothing or body coverings, such as hard
experiencing heat-related disorders ranging           hats, helmets or sports equipment for
from minor irritation of a heat rash to serious       example, add to the overall heat stress load.
conditions such as fainting, heat exhaustion
or potentially fatal heat stroke.                     Personal/Individual Factors
                                                      Some       personal   medical    conditions,
Learn about heat stress, symptoms and                 medications and individual levels of fitness
prevention measures to protect yourself and           may affect how you are able to cope with
others. (refer to Table #1 on page 4 for a            heat. Be sure to consult with your physician
summary).                                             if you are concerned about heat exposure.

Contributors to Heat Stress                           How Does The Body Cope with
Temperature and Relative Humidity                     Heat?
As the air temperature increases, your body           The human body has mechanisms that help
must work harder to keep cool.                        maintain a safe and relatively steady internal
                                                      core temperature of 37°C:
Humidity is a measure of the amount of
                                                         Sweating (cooling effect of evaporation)
moisture in air. At higher humidity levels,
                                                         Increasing blood flow to the extremities
sweat does not evaporate as easily and this
can contribute to heat stress.                           Increasing breathing rate.
Metabolic Heat Load - Physical Effort
Exercising, playing or performing physical            Sweating and Dehydration
activities generates body heat. This                  Sweating combined with inadequate fluid
metabolic heat load also adds to the overall          replacement is the biggest culprit when it
heat stress burden and the body’s                     comes to suffering serious, adverse health
mechanisms must work harder to keep cool.             effects. Sweating can lead to dehydration
                                                      and subsequent complications.      At high
Radiant Heat Sources                                  humidity levels [muggy weather], sweat
Radiant heat refers to heat [energy] emitted          does not evaporate well and the body’s
from sources such as ovens, furnaces or               ability to cool itself is reduced.    This
other hot processes, or from the sun if you           increases the risk of overheating and
                                                      becoming dehydrated.

                                             Page 1 of 5
Acclimatization                                      However, during hot muggy weather or heat
Acclimatization refers to a gradual                  waves, the effectiveness of building air-
adaptation of an individual to cope with             conditioning systems can be strained and
tolerate heat stress. Acclimatization is a           indoor      conditions       can       become
slow, complicated process and only occurs            uncomfortable. This generally does not
after physical activity under heat stress            pose a significant risk to healthy individuals.

A person will not be fully acclimatized to a         Humidex Rating
sudden higher level such as during a heat            A widely used measure to provide heat
wave. In Ontario, summers are not hot                stress awareness for the general1 population
enough for workers doing light work (sitting,        is Environment Canada’s “Humidex” rating.
standing, light arm work) to be considered           The Humidex is a subjective rating of how
acclimatized. This is important because you          hot the temperature “feels” based on various
must be careful to avoid working or                  combinations of temperature and relative
exercising intensely if it becomes very hot          humidity. It’s important to note that Humidex
and/or humid.                                        is determined from charts using temperature
                                                     and relative humidity measurements and is
PEOPLE AT RISK                                       not measured directly.
Anyone can be affected by heat stress.
Those generally at highest risk of suffering a       The Humidex can be used as an indicator of
heat-related disorder are those who:                 discomfort in offices, where the physical
       Work outdoors and/or in close                 demands and radiant heat sources do not
       proximity to significant heat sources         significantly contribute to the heat load.
       such as furnaces, ovens or hot
       asphalt.                                      The general ratings and comfort ranges are
       Perform strenuous work as this                summarized in the chart on page 5.
       contributes to the body’s overall heat
       burden.                                                  Note: Media reports of Humidex
       Don’t take regular breaks in cooler                      refer to the general outdoor
       areas (e.g. shady or air-conditioned                     conditions.     These may vary
       area).                                                   considerably and may not be
       Don’t consume enough fluids.                             representative of your particular
       Are susceptible because of a medical                     location or environment.    So, it’s
       condition.                                               important    to  take   site-specific
       Ignore symptoms of heat stress.                          temperature and relative humidity
                                                                measurements and determine your
                                                                own when referencing the Humidex
HEAT STRESS AND INDOOR WORKERS                                  ranges.
For indoor office workers, the risk of heat
stress is usually low because of the                 COPING WITH HOT WEATHER
relatively low physical effort required to           Here are some tips to help you cope with
perform tasks; the absence of significant            hot, humid weather and protect yourself
heat sources; cooling provided by fans or            from heat stress:
building air-conditioning systems and the
availability of water and other fluid                           Wear light coloured and lightweight
replacements.                                                   clothing.

                                                         People of all ages [e.g. young and elderly]

                                            Page 2 of 5
        Keep hydrated by drinking plenty of                    Seek medical attention if you feel
        cool fluids (preferably water). Drink                  dizzy or light headed.
        at least one cup every 20 minutes -
        even if you aren’t thirsty!                            Contact your supervisor if you have
                                                               concerns regarding working in the
        Take rest breaks in cool or shady                      heat
                                                               Watch for signs of heat stress in co-
        If you must work outside, try to avoid                 workers.
        working in the peak temperatures.

        Schedule work for cooler periods of                    Never ignore signs of heat
        the day (early morning or evening).
        Reduce the amount of physical effort
        required to perform strenuous tasks.


Click here to view the Ministry of Labour's Heat Stress Guideline

Click here to view CCOHS Information on Humidex and Heat Stress

Please contact the Occupational Health and Safety Department at extension 2225 if you have
any questions regarding working in the heat. Remember to always…

                                      Think Safe! Be Safe!

Occupational Health & Safety Office
Released: May 2012

                                                 Page 3 of 5
                                                          Table #1

                      Cause                    Symptoms                         Treatment                       Prevention
               Hot humid                                               Change into dry clothes often
                                          Red bumpy rash with                                               Wash regularly to keep
Heat Rash      environment; plugged                                    and avoid hot environments.
                                          severe itching.                                                   skin clean and dry.
               sweat glands.                                           Rinse skin with cool water.
               Heavy sweating from        Painful cramps               Move to a cool area; loosen
               strenuous physical         commonly in the most         clothing, gently massage and
               activity drains a          worked muscles (arms,        stretch affected muscles and         Reduce activity levels
               person's body of fluids    legs or stomach) which       drink cool salted water (1/4-        and/or heat exposure.
               and salt, which cannot     occur suddenly at work       1/2 tsp. salt in 1 litre of water)   Drink fluids regularly.
     Heat      be replaced just by        or later at home.            or balanced commercial fluid         Workers should check
    Cramps     drinking water.                                         electrolyte replacement              on each other to help
               Cramps occur from salt     Heat cramps are serious      beverage. If the cramps are          spot the symptoms that
               imbalance resulting        because they can be a        severe or don't go away after        often precede heat
               from failure to replace    warning of other more        salt and fluid replacement,          stroke.
               salt loss from heavy       dangerous heat-induced       seek medical aid. Salt tablets
               sweating.                  illnesses.                   are not recommended.
                                                                                                            Reduce activity levels
               Fluid loss and
                                                                       GET MEDICAL                          and/or heat exposure.
               inadequate water
                                                                       ATTENTION. Assess need for           Drink fluids regularly.
               intake and standing
                                          Sudden fainting after at     CPR. Move to a cool area;            Move around and avoid
               still, resulting in
                                          least two hours of work;     loosen clothing; make person         standing in one place for
    Fainting   decreased blood flow
                                          cool moist skin; weak        lie down; and if the person is       too long. Workers
               to brain. Usually
                                          pulse.                       conscious, offer sips of cool        should check on each
               occurs in
                                                                       water. Fainting may also be          other to help spot the
                                                                       due to other illnesses.              symptoms that often
                                                                                                            precede heat stroke.
                                          Heavy sweating; cool
                                                                       GET MEDICAL
                                          moist skin; body
                                                                       ATTENTION. This condition            Reduce activity levels
                                          temperature over 38°C;
               Fluid loss and                                          can lead to heat stroke, which       and/or heat exposure.
                                          weak pulse; normal or
               inadequate salt and                                     can kill. Move the person to a       Drink fluids regularly.
                                          low blood pressure;
  Heat         water intake causes a                                   cool shaded area; loosen or          Workers should check
                                          person is tired and weak,
Exhaustion     person's body's cooling                                 remove excess clothing;              on each other to help
                                          and has nausea and
               system to start to break                                provide cool water to drink;         spot the symptoms that
                                          vomiting; is very thirsty;
               down.                                                   fan and spray with cool water.       often precede heat
                                          or is panting or breathing
                                                                       Do not leave affected person         stroke.
                                          rapidly; vision may be
                                          High body temperature
               If a person’s body has
                                          (over 41 C) and any one
               used up all its water                                                                        Reduce activity levels
                                          of the following: the        CALL AMBULANCE. This
               and salt reserves, it                                                                        and/or heat exposure.
                                          person is weak,              condition can kill a person
               will stop sweating.                                                                          Drink fluids regularly.
                                          confused, upset or acting    quickly. Remove excess
     Heat      This can cause body                                                                          Workers should check
                                          strangely; has hot, dry,     clothing; fan and spray the
    Stroke     temperature to rise.                                                                         on each other to help
                                          red skin; a fast pulse;      person with cool water; offer
               Heat stroke may                                                                              spot the symptoms that
                                          headache or dizziness.       sips of cool water if the person
               develop suddenly or                                                                          often precede heat
                                          In later stages, a person    is conscious.
               may follow from heat                                                                         stroke.
                                          may pass out and have

                           Never ignore signs of heat stress!

    Ministry of Labour Heat Stress Health and Safety Guidelines, May 2011

                                                          Page 4 of 5
                                                Table #2
                                 HUMIDEX RATINGS AND COMFORT RANGES

        100%   95%   90%   85%     80%     75%   70%     65%     60%   55%      50%   45%   40%   35%   30%   25%   20%
21 °C     29    29    28    27      27      26    26      24      24    23       23    22
22 °C    31    29    29    28       28     27    26       26      24    24       23   23
23 °C    33    32    32    31       30     29    28       27      27    26       25   24    23
24 °C    35    34    33    33       32     31    30       29      28    28       27   26    26    25
25 °C    37    36    35    34       33     33    32       31      30    29       28   27    27    26
26 °C    39    38    37    36       35     34    33       32      31    31       29   28    28    27
27 °C    41    40    39    38       37     36    35       34      33    32       31   30    29    28    28
28 °C    43    42    41    41       39     38    37       36      35    34       33   32    31    29    28
29 °C    46    45    44    43       42     41    39       38      37    36       34   33    32    31    30
30 °C    48    47    46    44       43     42    41       40      38    37       36   35    34    33    31    31
31 °C    50    49    48    46       45     44    43       41      40    39       38   36    35    34    33    31
32 °C    52    51    50    49       47     46    45       43      42    41       39   38    37    36    34    33
33 °C    55    54    52    51       50     48    47       46      44    43       42   40    38    37    36    34
34 °C    58    57    55    53       52     51    49       48      47    45       43   42    41    39    37    36
35 °C          58    57    56       54     52    51       49      48    47       45   43    42    41    38    37
36 °C                58    57       56     54    53       51      50    48       47   45    43    42    40    38
37 °C                               58     57    55       53      51    50       49   47    45    43    42    40
38 °C                                            57       56      54    52       51   49    47    46    43    42    40
39 °C                                                             56    54       53   51    49    47    45    43    41
40 °C                                                                   57       54   52    51    49    47    44    43
41 °C                                                                            56   54    52    50    48    46    44
42 °C                                                                                 56    54    52    50    48    46
43 °C                                                                                       56    54    51    49    47

                                 Humidex                    Degree of Comfort
                                 20 – 29                        No discomfort
                                 30 – 39                       Some discomfort
                                 40 – 45              Great discomfort; avoid exertion
                                46 and over           Dangerous; possible heat stroke

                                Never ignore signs of heat stress!

                                                         Page 5 of 5

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