Heat stress prevention among farmers heading into Michigan’s summer
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EmailA tragic case study of fatal heat stroke illustrates why acclimation, rapid cooling and proactive employer prevention plans are necessary to save lives when high temperatures and physical labor combine.
As another Michigan summer is in full swing, it is important to be aware that hot weather is a hazard that can become lethal. An agricultural worker can overheat, leading to heat-related illness. Human bodies produce heat internally and the amount of heat produced increases with the intensity of work activity. On hot days, the internal heat produced through work activities plus high outdoor temperatures makes it more likely for the body to overheat. This is what happened when hot weather became a fatal hazard for a Michigan farmer.
Michigan fatality case study example
A male farm worker in his early twenties had been working in a field for about eight hours, staking posts for eggplant growth. This was his third day working that season. In the mid-afternoon, he began to complain about feeling hot. He was moved into the shade and given water. The maximum outdoor temperature for that day was 94 degrees Fahrenheit and had been above 90 F for several days. The farm worker became unresponsive and was transported to the hospital, where his temperature was recorded at 107.7 F. Ice bags, cold sheets and a fan were placed on him. Unfortunately, it wasn’t enough; he died the next day, with the cause of death listed as heat stroke.
While death is an extreme outcome of hot weather, even less severe outcomes can lead to time away from work. However, heat-related illness is preventable. It is helpful to know what contributes to heat stress to protect yourself and others.
What can increase the chance of heat-related illness?
- The weather: temperature, humidity and radiant heat from the sun.
- As humidity increases, it becomes harder for the body to remove excess heat and maintain the correct internal temperature.
- The temperature in full sun (no clouds) or partly cloudy/overcast can be 13 F or 7 F higher than in the temperature in the shade.
- Acclimatization or heat tolerance: through acclimatization (in Spanish), the human body becomes more efficient at removing excess heat and maintaining the correct internal temperature.
- New and returning workers require about five days (and up to 14 days) to safely adjust to a full outdoor workload.
- Note: According to OSHA, nearly three out of four fatalities from heat illness happen during the first week of work.
- Clothing and personal protective equipment (PPE):
- Clothing and PPE can prevent the human body from cooling by trapping heat and moisture.
- Workload:
- Physical work increases the human body’s internal temperature and may also increase dehydration due to loss of water through sweat.
- Personal factors:
- Dehydration, obesity, high blood pressure and other medical conditions (e.g., heart/respiratory disease, diabetes or a cold) add additional stress as the body tries to maintain the correct internal temperature, decreasing heat tolerance and increasing the likelihood of overheating.
- Some prescription medications can cause dehydration, prevent the body from sensing how hot it is or impair the body’s ability to maintain the correct internal temperature. Always check the label and speak with your medical provider.
- Sunburns can prevent the body from sensing how hot it is, which prevents the body from cooling itself.
- Prior heat-related illnesses can increase risk.
- Coffee, caffeinated drinks and alcohol are all diuretics, causing dehydration.
What does heat-related illness look like?
Heat-related illness can range from mild to severe. It is important to be able to recognize these signs and symptoms and know how to respond appropriately.
Call 911 immediately if severe symptoms occur such as confusion, slurred speech, loss of consciousness, seizures, nausea, vomiting, rapid pulse, high body temperature, hot dry skin or heavy sweating. After calling 911, move the person to a shaded or cool place and help lower their temperature by providing active cooling in the form of an ice bath, cold towels, and/or fans, and removing outer layers of clothing. Do not leave the person alone. For milder but still very serious form of overheating, lower the person’s body temperature and seek medical attention when a person working in hot conditions complains of being tired, thirsty, dizzy/lightheaded or is irritable.
Rhabdomyolysis (or rhabdo) is associated with heat stress and prolonged physical exertion. Symptoms include muscle cramps/pain, dark urine or reduced urine output, weakness and exercise intolerance. In response to symptoms, stop activity, drink liquids such as water and seek immediate medical care. Make sure to ask to be checked for rhabdo.
Signs and symptoms of mild heat stress can vary from a skin rash to muscle cramps to fainting. Heat rash appears as red bumps on the skin, often on the neck, upper chest or in skin folds. If you notice signs of heat rash, move to a cooler area, apply a cold compress and keep the area dry without ointments or creams. Muscle cramps, spasms, or pain usually in the legs, arms, or abdomen can be a result of heat cramps. If you experience heat cramps, move to a cooler area, drink water or an electrolyte beverage, and eat a snack. If fainting or dizziness occurs due to heat, move to a cooler area, sit or lie down and slowly drink fluids. Monitor symptoms and seek medical attention if in doubt.
What can you do to stay safe?
It is best to prevent heat stress by staying hydrated (in Spanish), taking breaks in a shady or cool area, changing any face coverings that become wet, and dressing appropriately for the heat. Take time to acclimate to sudden changes in conditions such as temperature and humidity. Employers should have a written heat stress prevention plan, acclimate workers when conditions change, establish an appropriate work/rest schedule (in Spanish), provide a shaded break area along with clean, cool water, and provide training to supervisors and employees on recognition of signs and symptoms.
If heat-related illness does occur, it is important to have a response plan and to look out for one another, as coworkers often first notice signs of heat stress in another employee.
Also make sure to identify hazardous heat conditions throughout the day by keeping track of the temperature, humidity, and where the work is being done, such as full sun, partly cloudy, or shade. Tools such as the OSHA-NIOSH Heat Safety Tool (in Spanish), a phone app, can help with keeping track of the weather, planning outdoor work activities, and remind you of first aid for heat-related illness.
Farm workers are at risk of heat stress due to the nature of physical outdoor work. Monitor daily maximum temperatures and humidity to better assess the possibility of heat stress and note that personal factors of each worker can increase risk. Learn the signs and symptoms of various heat-related illnesses and the appropriate response to signs you observe of symptoms you feel. If you are in doubt, call 911. Prevention is key to reducing and eliminating heat-related illnesses, so stay hydrated, take breaks and acclimate when the weather or work changes. If heat-related illness occurs, have an emergency response plan and ensure all workers on the farm are aware of the plan. Heat-related illnesses can be serious and even deadly, but it is preventable by assessing the risk and having an established prevention plan.
This work was supported by the AgrAbility Competitive Program of the USDA National Institute of Food and Agriculture (NIFA), grant number 2022-41590-38121, and cooperative agreement U60-OH008466 from the National Institute for Occupational Safety and Health.
Additional Resources
OSHA – Prevent Heat Illness at Work infographic in English and Spanish – consider posting this in an area where workers will see it.
MIOSHA Heat Illness Prevention Page with a customizable written prevention plan, training, and fact sheets.
OSHA Heat Illness Prevention Page with resources for both employers and employees.
