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6 100-BZM-01-IGDO ©2025, Workplace Safety & Prevention Services (WSPS) 1 877 494 WSPS (9777) | 905 614 1400 | WSPS.CA injured or drowning swimmers 6. Cold-Water Shock and Hypothermia Hazards Prevention Tips Hypothermia can occur in many environments and is defined as a core body temperature below 35.0 °C. Symptoms range from intense shivering with mild hypothermia to confusion, loss of coordination, and even death for severe hypothermia. Cold water shock is different. It is a set of involuntary physiological reactions specific to having the face and/or body suddenly immersed in cold water. The cold water causes involuntary gasping, further increasing drowning risk even in strong swimmers, along with hyperventilation, rapid heart rate, and even cardiac arrest from severe constriction of blood vessels. Hypothermia can also result if exposure extends beyond a few minutes. Common causes of hypothermia and cold-water shock in waterfront operations include: • Installing or removing docks and swimming areas early or late in the season when water temperatures are below 21°C (70 °F) • Wind chill, even on relatively warm days (even worse if the individual is wet) • Guarding in cool weather due to the inability to Know Your Water Temperatures and the Danger Zone • Cold water shock begins compromising breathing at temperatures below 25 °C (77 °F). At a water temperature of 21°C (70 °F), controlling breathing becomes difficult. Treat water below this temperature with caution. As the temperature falls, it becomes progressively harder to control breathing. • Water temperatures of 15°C (60 °F) and below are immediately life- threatening if rapid submersion occurs. Maximum intensity cold shock and complete loss of breathing control results. Drowning and death can occur in seconds due to involuntary gasping. If the worker survives the initial cold- water shock, hypothermia progresses rapidly and death is possible. Policies and Safe Work Practices • Consider avoiding the use of the waterfront, waterfront maintenance, and waterfront staff training when water temperatures are below 21°C (70 °F). • Where waterfront operations are required and where water entry is possible but not expected at water temperatures below 21°C (70 °F), develop measures and procedures to minimize the risk of cold-water shock and hypothermia. Dress for safer immersion. Assume workers WILL get become submerged. Safe work practices for non-entry activities such as maintenance may include providing drysuits with thermal clothing underneath, wetsuits, or immersion and floatation survival suits. • Safe work practices for water-entry activities, including training and rescue, at water temperatures below 21°C, include wearing wetsuits, avoiding rapid entry into water instead choosing gradual entry, and acclimatization. Acclimatization is a slow process where staff slowly develop control over their breathing and reduce the intensity of the cold-water shock reaction. Note that acclimatization does not reduce the risk of hypothermia, nor does it eliminate cold-water shock risks entirely, especially where the worker is submerged unexpectedly. • Consider closing the supervised waterfront when air temperatures are forecast to remain below 18°C for the duration of the day. Prolonged staff exposure to cool temperatures poses unique risks to aquatic staff. The necessity of light clothing (swimsuit, shorts and T-shirt) that will not hinder rescue eliminates using layers and thermal clothing to maintain body temperature in cool weather. Alternately, if maintaining supervised swimming, develop written measures and procedures to keep lifeguards warm, including access to an enclosed warming shelter that has supplemental heat in the form of central heating, radiant heater(s), and/or electric blanket(s). Provide frequent warm- up breaks.

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