Health and Safety Report
Volume 11, Issue 1

On Topic

Working on Ice Covered Water: Reducing Risksprint this article

Every winter there are people who fall through the ice into frigid water and get severely injured or die from hypothermia or drowning.

Those who work in extreme outdoor elements, including on ice over water, face great risk to their personal safety. Some of the occupations at high risk include rescue workers, environmental research teams, geophysical and support industries, scientists, and utility workers. There are however, safety precautions that can be taken to reduce the risk and prevent injuries and deaths. Understanding ice is a first step.

About ice

Fresh water freezes at 0° C and sea (salt) water at minus 2° C. But not all ice is created equal. Ice strength depends on quality and colour of ice, its thickness, the presence of cracks, ice and air temperatures, snow cover, as well as the size and depth of the water under the ice, currents, and distribution of the load on the ice.

Solid, clear blue ice forms when water freezes and is generally the strongest. White opaque ice (snow ice) that is formed when water-snow mixtures freeze on top of ice, has high air content, and is not as strong.

Ice must have a minimum density to be considered safe to walk or travel on, and the thickness and hardness required increase in proportion to the weight of the load and how it is distributed on the ice sheet. On both rivers and lakes, warm inflow from springs and currents can make the ice thinner. A sudden drop in air temperature can make ice become brittle and unsafe for use for 24 hours. Essentially, there is no absolutely "safe" ice.

Measurement charts from Work Safe Alberta (PDF) provide guidelines to help determine the thickness, strength and safety of the ice.

Careful attention should be given to reduced ice thickness close to shorelines.

Safety Precautions

You take a risk every time you go out onto ice. When working on ice over water, extreme caution must be used and additional safety measures should be taken. The following are a few practical tips to help keep you safe:

  • Everyone involved in work over ice must be trained in the hazards involved, safety precautions to be taken, basic rescue procedures, and emergency plans to be followed in the event of a breakthrough on the ice.

  • Wear layers of clothing that provide protection from wind and low temperatures but that wouldn't get in the way of your ability to swim or float if you fell through the ice. Wear a personal flotation device (PFD) and mitten-like ice claws. However if you are in a vehicle and the PFD would hamper your escape, do not wear one.

  • Take safety equipment with you such as a rope, and ice picks (keep in your pocket for easy access if you end up in the water), and carry a small personal safety kit that includes a pocket knife, compass, whistle, fire starter kit and cell phone.

  • Bring extra clothing, socks and gloves to change into if you fall through the ice or get wet.

  • Wear appropriate footwear (rubber treads, crampons) to prevent slipping.

  • Check the shoreline for signs of recent changes in water levels; if the ice is snow-covered, look for wet areas.

  • Measure the ice prior to use to determine whether it is thick enough to support the expected load.

  • Monitor the air temperatures for several days prior to going onto the ice and continue to observe them while working on the ice. If the ice is thick enough for the intended load, it should be safe to use if the air temperature has stayed below 0°C.

  • Buddy up. Never go out on the ice alone, and stay off the ice if there is any chance that it may be unsafe. Plans, including a return time, should be left with someone as a follow up measure. A cell phone, satellite phone or two-way radio is recommended for working at remote sites.

  • Check the ice on foot using an ice chisel to probe every 45 m (150 feet). If the chisel goes through, turn around and retrace the exact same steps back to shore. People on foot testing the ice should carry long poles, throw ropes, and an ice auger as rescue aids in case of a breakthrough, or be securely roped together, with minimum spacing of 15 m (50 feet).

  • Stay away from wet cracks, seams, pressure ridges, slushy areas and darker areas that may indicate thinner ice. Listen for loud cracks or booms coming from the ice; on river ice it may mean the ice is about to break up or move; on large lakes (several acres) this may be a harmless contraction.

  • For vehicle safety on ice, there are many factors that must be considered such as the load and conditions determining vehicle speed, and if doors and windows should be opened, and seat belts worn, to allow for easy escape. The resource list can provide you with more detailed advice.

These are just a few general precautions to ensure you don't let safety slip when working on ice covered water. You can find more detailed information and guidance in the links provided below.

Additional resources

OSH Answers

Take the Chill Out of Working in the Coldprint this article

Every winter parts of Canada are plunged into freezing temperatures and frigid cold. This is bad news for outdoor workers such as construction and utility workers, geologists, firefighters, and loggers for whom working in the cold can not only be hazardous to their health but also life threatening. The good news is that there are steps you can take to stay warm and safe, and take the chill out of working outside in the cold.

There are three challenges that must be addressed to enable workers to be safe in the cold: air temperature, air movement (wind speed), and humidity (wetness). Aside from several layers of protective, dry, clothing, and a healthy mix of physical activity, regular warm up periods can help you work safely in, and defend yourself from the cold.

How cold is too cold to work?

In Canada, there are no maximum exposure limits for cold working environments. The "work warm-up schedule" developed by the Saskatchewan Department of Labour has been adopted by the American Conference of Governmental Industrial Hygienists (ACGIH) as Threshold Limit Values (TLVs) for cold stress.

Effects of cold stress

Hypothermia (low body temperature) is the most common cold injury. Prolonged exposure to the cold causes the body to lose energy faster than it is produced, dropping body temperature. Warning signs are numbness, stiffness, drowsiness, poor coordination and sometimes even a lack of desire to get out of the cold. If any symptoms of hypothermia are present, immediately call for emergency assistance (911).

Frostbite is the second most common cold injury. Noses, ears, cheeks, fingers and toes are most often affected. The freezing constricts blood vessels, which impair blood flow and may cause permanent tissue damage. If only the skin and underlying tissues are damaged, recovery may be complete. However, if blood vessels are affected, the damage is permanent and could result in the amputation of the affected part.


Educate and inform workers and supervisors about symptoms of overexposure to cold, proper clothing habits, safe work practices, physical fitness requirements for work in cold, and emergency procedures. Clearly outline procedures for providing first aid and obtaining medical care and assign at least one trained worker per shift the responsibility of attending to emergencies.

Make heated warming shelters such as tents, cabins or rest rooms available for those who work continuously in sub-zero temperatures. Pace the work such that workers won't sweat excessively. If such work is necessary, provide proper rest periods in a warm area and allow employees to change into dry clothes. Give new employees enough time to get acclimatized to cold and protective clothing before assuming a full work load.

What to wear - top to bottom

To stay safe and dry, insulate yourself against cold temperatures, wind, and humidity with clothing appropriate for the type of work you will be doing and in the conditions you will be performing it. Wear several layers of loose clothing so you can regulate your comfort; remove a layer before you get too warm and start sweating, or add a layer if you are too cold. Under extremely cold conditions, heated protective clothing should be made available.

When you are using face protection in extremely cold conditions, make sure your eye protection is separated from your nose and mouth to prevent eye shields or glasses from fogging and frosting. Wear a wool knit cap or a liner under a hard hat to prevent heat loss.

If fine manual dexterity is not required, gloves should be used below 4°C for light work and below -7°C for moderate work. For work below -17°C, mittens should be used.

Wear socks that will stay dry and that are the right thickness for your boots - not so thick that they make your boots tight and squeeze your foot - and not so thin that they make your boots loose and cause blisters. Have extra socks so you can dry your feet and change socks during the day.

Keep your feet warm in felt-lined, rubber bottomed, leather-topped boots that breathe and let perspiration evaporate. However, if work involves standing in water or slush (e.g., fire fighting, farming), be sure to wear waterproof boots. While they protect the feet from getting wet from cold water, they also prevent the perspiration from escaping. Socks will become wet more quickly and increase the risk for frostbite.

Other prevention tips

  • Avoid using alcohol, nicotine or other drugs that may affect blood flow and cause the body to lose heat and thus increase the risk of hypothermia.

  • Don't expose yourself to cold temperatures after a recent shower or bath.

  • Keep moving; avoid sitting or standing still for long periods of time.

  • Take regular breaks from the cold in warm places.

  • Eat properly and frequently to maintain body heat and prevent dehydration.

  • Drink fluids (hot non-alcoholic beverages or soup) often especially when doing strenuous work to keep warm and hydrated. Limit the amount of caffeinated drinks as they can dehydrate you and cause you to lose body heat.

More information from CCOHS

Working in cold environments (Threshold Limit Values) fact sheet

Health effects and first aid fact sheet

General effects of working in the cold fact sheet

Cold Weather Workers Safety Guide

Health and Safety To Go

Podcasts: Welding Safety and Winter Drivingprint this article

This month's Health and Safety To Go! podcasts provide welding safety tips and feature a timely encore presentation on winter driving tips.

Feature podcast: Welding: Don't Get Burned

Everybody knows that welding can be a dangerous activity. This tips-based podcast explores the occupational hazards associated with welding, and offers some concrete precautions and recommendations for staying safe on the job.

The podcast runs 2:21 minutes. Listen to the podcast now.

Encore Podcast: Winter Driving Tips

CCOHS shares tips on how to drive safely in extreme weather such as snow, ice and slush.

The podcast runs 3:25 minutes. Listen to the podcast now.

CCOHS produces free monthly podcasts on a wide variety of topics designed to keep you current with information, tips, and insights into the health, safety, and well-being of working Canadians. You can download the audio segment to your computer or MP3 player and listen to it at your own convenience... or on the go!

See the complete list of podcast topics. Better yet, subscribe to the series on iTunes and don't miss a single episode.


Get the Picture: GHS Pictograms and Hazards print this article

The US Occupational Safety & Health Administration (OSHA) has recently implemented the Globally Harmonized System for Classification and Labelling of Chemicals (GHS). For the first time ever, OSHA labels will be required to show a pictogram to help convey hazard information. In Canada, we are starting to see the GHS pictograms on (Material) Safety Data Sheets and product labels. Within the next few years, WHMIS (Workplace Hazardous Materials Information System) will also implement the GHS.

To help workers identify the hazards identified by GHS and understand the new information they are seeing, CCOHS has developed a colourful, easy to read poster. As with all CCOHS awareness posters, it can be downloaded for free as a PDF and is also available for sale as a 16"x 25" print (double-sided, with English on one side and French on the other).

More information about the GHS Pictograms and Hazards poster.

Related CCOHS Resources


WHMIS After GHS: An Introduction, free

WHMIS After GHS: How Suppliers Can Prepare, free

HazCom 2012 for Workers

Key topic page: Chemicals & Product Safety


MSDS -> SDS: Not Just Dropping the "M"

WHMIS Hazard Symbols


Implementing a Chemical Safety Program

MSDS Publications

WHMIS After GHS Fact Sheets, free

WHMIS After GHS: Preparing for Change




Last Word

Milestone: By the Numbersprint this article

This issue marks the ten year anniversary of the Health and Safety Report. Since that very first article on Safety Urban Legends: Fact or Fiction?, we have produced 114 issues of the newsletter, providing practical information in 569 articles to help you work more safely. We have covered countless topics that covered the gamut of health and safety including nanotechnology, occupational disease, ergonomics, mental health, workplace bullying and violence, safe work practices, hazard alerts and more.

Today there are more than 32,000 subscribers to the Report in over 100 countries around the world - from Algeria, to Monaco, to Brazil, and of course to Canada. And through the years we have tried our best to stay abreast of current and emerging issues related to workplace health and safety to keep you up to date. There is one thing that has never changed: our commitment to providing you with credible information, guidance and resources that are relevant and useful.

Help us as we continue in this tradition of striving for excellence in the Health and Safety Report. Tell us your health and safety challenges and/or what topics you would like to see in the Report, and help us provide information you can use.

On behalf of the production and editorial team, thank you for subscribing to the Health and Safety Report.

Lynda Brown


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