Cold : A risk factor for MSDs
Working in a cold environment poses health hazards. Direct exposure to cold can lead to serious conditions such as hypothermia and frostbite. Furthermore, cold temperatures increase the risk of musculoskeletal disorders (MSDs) and can result in workplace accidents.
In a neutral environment, the body maintains a stable temperature of 37°C (98.6°F). However, when exposed to cold for extended periods, some parts of the body may adapt, while others may become weakened or even deteriorate.
Let us explore how cold affects our bodies and how it contributes to the increased risk of MSDs.
The effects of cold on the body
When exposed to cold, the body activates mechanisms to retain heat, such as cutaneous vasoconstriction. Shivering can increase the production of body heat by up to 500%. Additionally, the body compensates for heat loss by generating its own heat, primarily through the conversion of energy from food and the effects of physical activity.
Unlike heat, where the body can acclimate, cold only allows for a limited tolerance in certain areas of the body – but this does not equate to full acclimatization.
The hypothalamus, a gland located at the center of the brain, functions as the body’s thermostat. Thermoreceptors located on the skin—primarily on the face, ears, hands, and feet—as well as along the spinal cord, detect the body’s internal temperature and the temperature perceived externally. This information is then transmitted to the hypothalamus.
The body’s ability to maintain a stable temperature is known as homeothermy, which enables optimal metabolic function. Here are some key physiological factors important for the body’s heat production:
- Food intake;
- Energy reserves (glycogen*);
- Physical activity;
- Shivering – a reflex response that increases heat production when needed. However, this reaction can only be sustained for a few hours due to the depletion of muscle glycogen reserves and resulting fatigue.
Furthermore, we are not all affected by the cold in the same way. Various factors influence our resistance, including specific medical conditions, different metabolic rates, age (children and the elderly), and hormonal causes.
Cold and MSDs
According to INRS recommendations, a work environment is considered cold when the air temperature is below 18°C (64.4°F).
Certain professions require working in cold environments:
- The food industry (slaughterhouses, frozen product packaging, cold storage rooms, etc.);
- Outdoor work in winter (construction, agriculture);
- The transportation and logistics sector;
- Work in refrigerated warehouses.
Cold can have several impacts on the body, such as increased fatigue, loss of dexterity, numbness, and cramps. It can also be a direct or indirect cause of workplace accidents. For instance, cold may lead to drowsiness or varying degrees of pain, which can result in accidents such as slips, falls, or lapses in attention, thereby increasing the risk of incidents.
Working in the cold can reduce mental performance (longer reaction times, slower decision-making, etc.) and impair sensation and dexterity (as early as 15°C/59°F). This can lead to an increase in the force applied during physical effort, raising the likelihood of musculoskeletal disorders (MSDs).
As previously mentioned, the body is particularly vulnerable to cold—note that hypothermia sets in below 35°C (95°F). Working in cold conditions therefore raises the risk of MSDs, exacerbated by insufficient rest, extreme postures, and repetitive movements. Combined with low temperatures, the body becomes even more exposed.
Environmental factors can indirectly aggravate the risk of MSDs. When individuals are subjected to these factors, their vulnerability increases.
Examples of environmental factors include noise levels, vibrations, dust, lighting, and most notably, exposure to cold. Cold disrupts manual activity and leads to imprecise movements, frostbite, cramps, hypothermia, reduced blood flow to the fingers (linked to Raynaud’s syndrome), and more.
The Raynaud’s syndrome is a circulatory disorder that primarily affects the fingers and, in some cases, the toes. Exposure to cold triggers symptoms such as paleness, a sensation of cold, and loss of sensitivity that can last from a few minutes to several hours. Workers in certain professional sectors are more prone to developing Raynaud’s disease.
Aggravating factors in cold environments
Often caused by cold and the work environment, humidity is an aggravating factor. In addition to increasing the body’s sensitivity to cold, humidity can make surfaces slippery, thereby increasing the risk of falls and workplace accidents.
Cold being a sensitizing factor for the body, shocks or vibrations worsen the situation. Indeed, the body becomes much more sensitive as the musculoskeletal structures are weakened due to the cold.
Solutions for improvement
The French labor Code does not specify minimum working temperatures or provide particular provisions related to working temperatures. However, employers are required to train, inform, and implement preventive measures to reduce health risks associated with working in cold environments.
In terms of regulation, Article R4213-7 of the Labor Code states that: “The equipment and characteristics of the work premises are designed to allow the temperature to be adapted to the human body during working hours, considering the work methods and the physical constraints borne by workers.”
Additionally, according to the decree of January 8, 1962: “During periods when workers who are habitually assigned to outdoor workstations are subjected to special conditions due to exposure to bad weather, employers must provide at least one non-alcoholic hot beverage.”
Some other preventive measures include :
- Limiting exposure time to cold to promote operator versatility and increase job rotations;
- Teamwork : at least two people working in refrigerated rooms to enhance worker safety (< -30°C);
- Wearing gloves when handling objects at temperatures < 0°C;
- Prohibiting cold work for pregnant women when the temperature is below 0°C (Article R234-4**).
Conclusion
Sources :
INRS – https://www.inrs.fr/risques/froid/accidents-effets-sante.html
Resistance to cold : https://www.europe1.fr/societe/pourquoi-nous-ne-sommes-pas-egaux-face-a-la-sensation-de-froid-3587141
Exposure to cold : https://www.cchst.ca/oshanswers/phys_agents/cold/cold_general.html
Labor Code : https://www.legifrance.gouv.fr/loda/id/LEGIARTI000006676880/1962-01-20/#LEGIARTI000006676880
Raynaud’s Syndrome : https://www.ameli.fr/assure/sante/themes/phenomene-raynaud/definition-symptomes-causes#:~:text=Le%20ph%C3%A9nom%C3%A8ne%20de%20Raynaud%20est%20d%C3%A9clench%C3%A9%20le%20plus%20souvent%20par,absentes%20lorsqu’il%20fait%20chaud.