Staying Warm and Safe

As winter sets in, outdoor workers need to reaquaint themselves with the art of dressing right and staying warm. Workers who are at risk of cold exposure span a gamut of industries that include construction, transportation, utilities and telecommunications, first response, military, meat packaging and fishing, hhuntng and trapping.

Cold affects work performance in many ways. Working in freezing temperatures lowers work efficiency by impairing mental alertness. It also hinders manual tasks by compromising dexterity, reducing muscular strength and causing stiffened joints. All these factors can heighten the likelihood of accidents.

A person’s heat retention and tolerance to cold depends on body structure (such as the size and shape of the body and the layer of fat under the skin), certain reflex and behavioural mechanisms that retain heat within the body and the outfits they wear. Other predisposing conditions that makes one more susceptible to cold injury include age, diseases of the blood circulation system, injuries resulting in blood loss or altered blood flow, previous cold injury, fatigue, smoking or consumption of alcohol and use of certain drugs or medication.

Gender is another an influencing factor, with studies showing that women’s response to cold differ from that of men. Core body temperature cools more slowly in women, and they are not usually able to create as much metabolic heat through exercise or shivering. The rate of cooling of the extremities like the feet and hands is also faster among women. As a result, women are generally at a greater risk of cold injury.

A cold environment presents challenges through air temperature, wind speed and humidity. In order to work safely, these challenges have to be counterbalanced by proper insulation through layered protective clothing, physical activity and controlled exposure to cold.

In Canada, the legislation in some jurisdictions provides a range of acceptable temperatures for specific circumstances; other jurisdictions use the Threshold Limit Values for cold stress as published by the American Conference of Governmental Industrial Hygienists (ACGIH). Some Canadian jurisdictions have adopted these TLVs as occupational exposure limits, while others use them as guidelines.

To protect outdoor workers from the adverse effects of cold exposure, warm-up breaks should be scheduled according to weather conditions, such as when wind or temperature increases. For continuous work in temperatures below the freezing point, heated warming shelters such as tents, cabins or rest rooms should be made available.

The work should be paced to avoid excessive sweating, as this would cause the clothing near the skin to become wet, thereby increasing the risk of cold injuries. For those who engage in physically strenuous tasks, proper rest periods in a warm area should be allowed for employees to change into dry clothes should excessive perspiration occur. New employees should be given enough time to get acclimatized to cold and protective clothing before assuming a full work load.

Apart from scheduled warm breaks, the risk of cold injury can be also minimized by proper equipment design, safe-work practices and appropriate clothing. For work below the freezing point, the ACGIH recommends that metal handles and bars should be covered by thermal insulating material; machines and tools should be designed so that they can be operated without having to remove mittens or gloves.

Emergency procedures for providing first aid and obtaining medical care should also be outlined, and at least one trained person should be assigned the responsibility of attending to emergencies for each shift. Employees and supervisors involved with work in cold environments should be trained to identify symptoms of hypothermia, safe-work practices and emergency procedures in case of cold injury.

When selecting personal protective equipment (PPE) for protection against the cold, one needs to consider weather conditions, the level and duration of activity and job design. Clothing should be worn in multiple layers, as the air between layers of clothing provides better insulation than a single thick garment. Layering also enables the wearer to remove a layer when it starts to get too warm.

For work in wet conditions, the outer layer of clothing should be waterproof. If the work area cannot be shielded against wind, an easily removable windbreak garment should be used. Under extremely cold conditions, heated protective clothing should be made available if the work cannot be done on a warmer day. It is also important to keep clothing clean since dirt fills air cells in fibres of clothing and destroys its insulating ability. Cotton is not recommended as it tends to get damp or wet quickly, losing its insulating properties. Wool and synthetic fibres, on the other hand, retain heat when wet.

The article is based on information provided by the Canadian Centre for Occupational Health and Safety in Hamilton, Ontario.