Baby, It’s Cold Outside!

Baby it’s Cold Outside!

It’s finally here…. Old man winter has made his presence known here in Saskatchewan.  Along with cold temperatures we have had wind chills as well which makes it feel even colder out there.  There are three main factors that modify our response to cold: air temperature, air movement (wind speed), and humidity.  For those who have to work in our sometimes harsh winter environment, these challenges have to be counterbalanced in order to work safely.  A few things to keep in mind while reading this article are the following:

  • Air Temperature is measured in degrees Celsius or Fahrenheit by an ordinary thermometer.
  • Wind speed is measured in meters per second or kilometers per hour or miles per hour. The following is a guide for estimating wind speed:
    • 8 km/h – light flag moves
    • 16 km/h – light flag fully extended
    • 24 km/h – raises a newspaper sheet
    • 32 km/h – causes blowing and drifting snow
  • Humidity or rather wetness effects body temperature as water conducts heat away from the body 25x faster than dry air.

Whenever wind speed increases a person feels colder regardless of the air temperature.  This combined effect of wind speed and cold air temperature is known as the ‘wind chill’.  Basically it is the calculation of the feel of what the air temperature would be on exposed human flesh.  The following is chart representing wind chill hazards and what to do as per Environment Canada:

Table 2
Wind Chill Hazards and What To Do
Wind Chill Exposure Risk Health Concerns What to Do
0 to -9 Low risk
  • Slight increase in discomfort
  • Dress warmly
  • Stay dry
-10 to -27 Moderate risk
  • Uncomfortable
  • Risk of hypothermia and frostbite if outside for long periods without adequate protection.
  • Dress in layers of warm clothing, with an outer layer that is wind-resistant.
  • Wear a hat, mittens or insulated gloves, a scarf and insulated, waterproof footwear.
  • Stay dry.
  • Keep active
-28 to -39 High Risk: exposed skin can freeze in 10 to 30 minutes
  • High risk of frostnip frostbite: Check face and extremities for numbness or whiteness.
  • High risk of hypothermia if outside for long periods without adequate clothing or shelter from wind and cold.
  • Dress in layers of warm clothing, with an outer layer that is wind-resistant
  • Cover exposed skin
  • Wear a hat, mittens or insulated gloves, a scarf, neck tube or face mask and insulated, waterproof footwear
  • Stay dry
  • Keep active
-40 to -47 Very high risk: exposed skin can freeze in 5 to 10 minutes

(In sustained winds over 50 km/h, frostbite can occur faster than indicated.)

  • Very high risk of frostbite: Check face and extremities for numbness or whiteness.
  • Very high risk of hypothermia if outside for long periods without adequate clothing or shelter from wind and cold.
  • Dress in layers of warm clothing, with an outer layer that is wind-resistant.
  • Cover all exposed skin.
  • Wear a hat, mittens or insulated gloves, a scarf, neck tube or face mask and insulated, waterproof footwear.
  • Stay dry
  • Keep active.
-48 to -54 Severe risk: exposed skin can freeze in 2 to 5 minutes

(In sustained winds over 50 km/h, frostbite can occur faster than indicated.)

  • Severe risk of frostbite: Check face and extremities frequently for numbness or whiteness.
  • Severe risk of hypothermia if outside for long periods without adequate clothing or shelter from wind and cold.
  • Be careful. Dress very warmly in layers of clothing, with an outer layer that is wind-resistant.
  • Cover all exposed skin
  • Wear a hat, mittens or insulated gloves, a scarf, neck tube or face mask and insulated, waterproof footwear.
  • Be ready to cut short or cancel outdoor activities.
  • Stay dry.
  • Keep active.
-55 and colder Extreme risk: exposed skin can freeze in less than 2 minutes
  • DANGER! Outdoor conditions are hazardous.
  • Stay indoors.

 

Although there are no maximum exposure limits for cold working environments in Canada, there are guidelines that can be used to create safe work plans and protect the health and safety of workers who may be exposed to colder temperatures.  The Saskatchewan Department of Labour developed a “work warm-up schedule” which has been adopted by the American Conference of Governmental Industrial Hygienists (ACGIH) as Threshold Limit Values for cold stress.  This “work warm-up schedule” gives guidance for warm up breaks that may be needed when working in colder temperatures.  As the wind speed increases and/or when the temperature decreases additional breaks should be taken.  All non-emergency work should be stopped at temperatures of -43 degrees Celsius if there is no noticeable wind.  The following chart outlines the break times in more detail:

 

jan-9-chart

Note:

  • Applies to moderate to heavy physical work in any 4-hour period
  • Warm-up breaks should be in a warm environment for 10 minutes
  • Norm breaks means the normal break after 2 hours of work
  • Guidelines apply to workers wearing dry clothing
  • If there is limited physical activity, apply the schedule one step lower (more protective)

So what else can we do to prevent the adverse effects of cold?

  • Equipment design – when working below the freezing point, machines and tools should be designed so that they can be operated without having to remove gloves or mittens. Also metal handles and bars should be covered with a thermal insulating material.
  • Emergency procedures – the provision of first aid and obtaining medical care should be outlined clearly and at least one fully trained person should be assigned each shift with the responsibility of attending emergencies.
  • Training – Supervisors and workers should be trained regarding working safely in cold environments and be familiar with the adverse effects of exposure to cold.
  • Personal Protective Equipment – Protective clothing should be selected to suit the temperature, weather conditions and job design. Dress in layers with a wind resistant outer layer.  Almost 50% of body heat is lost through the head so wear a hat (a wool cap or liner under a hard hat can reduce excessive heat loss).  Felt lined, rubber bottom, leather topped boots with removable felt liners are best for heavy work in cold temperatures since the leather is porous allowing the boots to breathe and let perspiration evaporate.  Always keep your socks dry so carry extra pairs with you.

Remember to listen to the weather forecast and plan ahead!

 

References:

http://www.ccohs.ca/oshanswers/phys_agents/cold_working.html

https://www.getprepared.gc.ca/cnt/rsrcs/sfttps/tp201101-eng.aspx

 

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