Well-drilling is one of the occupations in which workers have to be extremely careful and observant when it comes to heat stress. This is because of the obvious environmental factors of outdoor labor and the job locations where workers may be far removed from both medical help and adequate means of cooling.
Environmental factors that can lead to heat stress in well-drilling include the temperature, radiant heat from the sun, and exposure to heat through convection or conduction from being near to or handling hot equipment. Low air velocity also plays a role, as does high humidity. Sweating is an important means by which the body maintains a stable internal body temperature. If the air is moving, the breeze helps sweat evaporate and cools down the body. However, sweating is only effective if the humidity level is low enough to permit evaporation.
Clothing affects evaporation as well. Personal protective equipment (PPE), such as vapor-barrier coveralls, hinders the body’s ability to thermoregulate by sweating.
Another factor is work demand. Work produces metabolic heat, which will raise the core body temperature if it is not effectively dissipated.
Personal factors affect how susceptible a worker may be to heat stress disorders. General physical fitness, consumption of alcohol or prescription medications, and prior heat injury all impact the responses of the body to heat.
Forms of Heat Stress Disorders
Heat stress disorders occur when the worker’s body loses its ability to regulate its core temperature. The body cannot rid itself of excess heat through sweating, which is the primary means of heat dissipation.
Heat stroke is the most dangerous of the heat stress disorders. A worker may
appear confused, agitated, or irrational, or even lose consciousness. Breathing may become faster and deeper than normal. The core temperature may be as high as 109°F (43°C). Other symptoms may include hot but dry skin that may be red or pale blue due to insufficient oxygen, although someone suffering from exertional heat stroke may have wet skin.
Heat stroke victims can die without treatment. Medical assistance should be summoned immediately. In the interim, the victim should be moved into the shade, or air conditioning if available, and the body cooled with cold water or ice packs applied to the wrists, arm pits, groin, or neck. Small quantities of water — a half glass every 15 minutes — should be given to the victim to drink, but not so much as to induce vomiting. When the body temperature has come down to about 102°F (39°C), body cooling can be stopped, but the victim should be kept in a cool place. It is imperative that people who work in hot conditions, especially in isolated outdoor areas, know the symptoms of heat stroke and the first aid techniques required to stabilize a victim until medical assistance arrives. This training can mean the difference between life and death.
Other forms of heat stress include heat exhaustion, which usually results when a worker is sweating and not replenishing fluids. The person may have clammy, moist skin and a pale or red complexion, and may experience thirst, fatigue, headache, dizziness, or nausea. The best solution to heat exhaustion is for the worker to rest in a cool area and drink an electrolyte solution (like a sports drink) that quickly restores potassium, calcium, and magnesium salts.
Workers suffering from heat stress may experience heat cramps from failing to replace their bodies’ salt loss due to sweating. Drinking water or a 0.5% salt solution and massaging the cramping muscles help to relieve the symptoms.
Heat rash may appear if profuse sweating causes the sweat glands to become clogged. The skin becomes itchy with small red spots and is sensitive to radiant heat. If not treated, heat rash can be very uncomfortable (it is also known as prickly heat) and can lead to infection. It can be prevented by resting in a cool place, allowing the skin to dry, and keeping the skin clean.
Preventing Heat Injury
Many engineering controls that can be used to prevent heat injury indoors, such as ventilation or isolating the heat source, are not practical or possible for workers at well-drilling operations. This is why training in preventing, recognizing, and treating the effects of heat stress should be an essential component of any well-drilling company’s health and safety plan.
Well-drilling workers in the field can incorporate some basic safety measures into their work practices to prevent heat stress disorders. The most important is fluid replenishment. Some workers may be reluctant to drink plenty of fluids because they do not want to stop constantly for bathroom breaks, but when workers are laboring in a hot environment, sufficient fluid replenishment is critical. Thirst is not a good indicator of the need for water replacement. Workers should take a drink every 15 to 20 minutes.
Other good work practices involve administrative controls such as rotating workers away from heat sources, avoiding heavy work during the hottest hours of the day, and providing shade and, if possible, air conditioning where workers take their breaks. Frequent breaks out of the sun should be encouraged. PPE that may be trapping body heat should be removed during the breaks. Another administrative practice is to reduce the work load so that workers are not producing so much metabolic heat in the first place. A buddy system should be in place so a worker is never alone in a hot environment; in case the worker suffers from heat stress disorders, a trained co-worker will be able to recognize the symptoms and help.
Acclimation is very important. New workers and workers returning to the job after more than a couple of days’ absence need to gradually become accustomed to working in the heat. It makes no difference how many years of working in hot conditions a worker has under his belt. Depending on the environment and other factors, it can take seven to 14 days to become acclimated or reacclimated, even if the worker has been away for as little as one week. Heat acclimation is lost much faster than it is gained.
Well-drillers in the field may benefit from PPE originally developed by the aerospace industry, such as reflective clothing or ice vests that circulate cooling fluid. My favorite race car drivers wear this type of PPE too. It provides an effective means of cooling. However, the weight of the garment along with its accessories should be considered when used in the well-drilling industry.
Industrial hygienists have various qualitative and quantitative methods for evaluating heat stress, taking into account the thermal environment, work demands, clothing, and the worker’s subjective comfort level. They may also use instruments such as personal heat strain monitors to measure the worker’s physiological responses. Industrial hygienists are not typically in the field with well-drillers; therefore, other than maintaining physical fitness and a healthy lifestyle, the most valuable tool that workers have when working in a hot environment is their training — knowing the prevention techniques, signs, symptoms, and first aid that could save their own, or a co-worker’s, life.
To access a list of industrial hygiene consultants who specialize in hot weather safety issues, visit the American Industrial Hygiene Association website at www.aiha.org and go to the consultants listing.
About the Author
Margaret Wan, PhD, works with Kaiser Permanente’s National Environmental Health and Safety Department. She is a member of the American Industrial Hygiene Association and serves on the association’s Ergonomics and Communications and Training Methods Committees.
