Don't get beat by the summertime heat

John Shutske and Jim Versweyveld
On this day, it was 93⁰F at 11:30 a.m. with a 52% humidity – putting the “Heat Index” at 102⁰F (higher if in direct sunshine), a condition considered to be 
moderately high risk requiring extra precautions and awareness.

Summertime can be a big challenge for farmers and their employees as they work through long days with high temperatures and humidity levels. We usually begin to hear about heat stress in the later weeks of May or early June through shortly after Labor Day.

In recent years, the ‘dog days’ of summer with high heat and humidity have started earlier and earlier, and dangerous conditions occur more often. There has been a lot written for farmers in recent years about the importance of protecting animals from hot and humid conditions, but we need to pay equal attention to our health and the well-being of hired workers and family members.

Most of the statistics around health-related deaths and health problems in agriculture come from those who work in crop production. One study found that the rate of farm worker deaths from heat stroke was 20 times higher than the rate for US civilian workers overall.

This can include tasks where we have outside exposures or work in unventilated, hot locations. Some examples would include baling hay, operating a skid steer offers only limited shade, calf care, performing outside maintenance on buildings, working inside a hay or grain storage area, or hand labor in the field or garden.

Heat-related illness can develop quickly and can then rapidly progress into deadly stages. Because heat stress (that includes heat exhaustion and/or heatstroke) affects our thinking and mental processes, sometimes we do not recognize or feel the negative impacts. Unfortunately, if we don’t act, this can be deadly. Unrecognized heat exhaustion – an early but dangerous stage of heat-related illness – will rapidly progress to heatstroke. A significant percentage of people who develop heatstroke will die.

When high air temperature is combined with a high relative humidity, a direct measurement of water vapor in the air, our body is unable cool itself effectively because sweat does not evaporate quickly.

It’s common to see weather forecasters on TV or through weather apps refer to the “heat index.” This is a measurement that incorporates both the temperature and humidity. When the heat index is forecast to be 90 or higher, extra precaution is vital, though heat stress can and does occur at lower levels.

A heat index above 103 is considered VERY high risk. Also, if working in sunlight, the sun exposure adds up to 13.5 degrees to the heat index. So, you might hear your weatherperson say that “today’s heat index is going to be 85 degrees F,” but if it’s bright and sunny, the actual heat index felt by your body will be 98.5 degrees.

The humidity level is important because when we ‘work up a sweat’ it helps cool us. Evaporation of moisture from our skin means that heat is moving from the skin into the surrounding air. But…high humidity levels dramatically slow sweat evaporation.

Sunshine also adds to this effect as exposed skin and clothing also heats up due to the sun’s radiation. When our body temperature gets too high from working in these conditions, it  impairs a person’s ability to think correctly and make complex (or even simple) safety-related decisions. Heat stress slows down our reaction time. Heat and humidity lead to us not using important personal protective equipment for key farm activities. All these impacts of high temperature and humidity lead to increased risk of injury.

It's also important to note that youth and older people have a higher risk for heat-related health issues since they can have a more difficult time regulating body temperature. In the case of kids, they have a smaller body mass-to-surface area ratio as compared to adults. This is like having a motor vehicle with an undersized radiator. It’s more complex with older people, but as we age, we are not as effective at cooling ourselves as a result of circulatory changes and our sweat glands do not function as efficiently as younger people.

During any physical activity, the body generates heat. The greater the intensity of the work, the more heat. A person’s ability to stay cool also depends on clothing, conditioning to heat and humidity, and level of health and fitness along with the factors connected to age. Air movement due to natural breezes or fans help carry away heat.

What Should I Look for to Avoid Heat Stress?

Here are a few indicators of heat-related illness and recommendations for treatment from the American Red Cross:

Heat exhaustion:  Unchecked, heat exhaustion will progress toward heatstroke. Symptoms are cool, moist, pale, or flushed skin with heavy sweating, headache, nausea, or vomiting, dizziness, and exhaustion. A person with heat exhaustion may have rising body temperature, but not always. If heat exhaustion is suspected, the person must be moved to a cool, shaded place. Clothing should be loosened, and moist cloths applied to the forehead, wrists, and chest to cool down. An alert person should slowly drink cool fluid every 15 minutes. If symptoms do not improve after an hour or if they refuse fluids, vomit, or lose consciousness, call 9-1-1. Any person with underlying health conditions (kidney, lungs, heart, etc.) should see a doctor right away.

Heatstroke: Heatstroke must be treated as a life-threatening emergency. Call 9-1-1 without delay. Symptoms are hot, red skin, changes in consciousness, a rapid and/or weak pulse, and rapid, shallow breathing. A person experiencing heatstroke can have a high body temperature — sometimes as high as 103-105 degrees Fahrenheit (or even higher). Skin will often feel dry, but not always. While waiting for help, the person must be cooled quickly by being carefully immersed in cool (but not cold) water or applying saturated cloths with cool water. Fans can be used to speed cooling. A person with heatstroke should sip cool liquids, but only if they are alert. The person should be monitored continuously until help arrives as in any urgent first-aid situation.

What are some steps to help farmers, family members, and workers reduce heat stress?

  • Plan difficult jobs during cooler times of the day—of course, this usually means early in the morning or late in the day.
  • Allow employees to gradually adjust to hot conditions over several days by initially exposing them to short work periods and more frequent breaks. But, even for those who comfortable in the heat, monitor and supervise their condition closely.
  • Drink often! Water is the usually the best drink for outdoor work. Occasional sports drinks are okay for most people. Avoid sugary soda and caffeine.
  • Where it’s possible, work in shaded, ventilated areas (with either a fan or breeze) whenever possible.
  • Watch for high temperature/high humidity outdoor conditions and adjust assignments to reduce risk.
  • Wear lightweight, breathable clothing. Light colors are cooler.
  • Wear a loose-fitting, wide-brimmed hat to provide sun protection.
  • Apply sunscreen to protect against sunburn and skin cancer.
  • Salt tablets are not recommended unless advised by a doctor.

·       Anyone who must restrict fluid intake because of a medical condition should check with a doctor about safe work in hot weather.

Resources for medical assistance for workers without health insurance

Some employers have hired workers who are not insured or have other limitations if they need emergency medical care. This should never limit a person’s ability to get needed medical care and treatment.

In Wisconsin, people who live or work on a farm can receive information on various forms of assistance by calling 2-1-1. Additionally, there is a network of healthcare facilities and professionals who provide healthcare for special populations. This can include migrant and seasonal farmworkers and their families. Health Centers around the state can be found at:

These facilities are expected to provide comprehensive, culturally-competent primary health care services to everyone in the community. Health Centers provide care to populations facing barriers to health and health care, including (but not limited to) school-aged children, the elderly, pregnant women and infants, immigrants and refugees, the LGBTQ+ community, people with disabilities, and military veterans.

Bottom line…there’s a ton of work to be done on farms in the summer! The work is vital to farming businesses, families and local communities. But, it’s important that you take the risks associated with heat (and humidity) seriously so that you don’t get “beat by the heat!”

John Shutske is a professor of biological systems and engineering and is also an extension specialist at University of Wisconsin-Madison.
Jim Versweyveld

John Shutske, Extension Agricultural Safety and Health Specialist & Jim Versweyveld, Outreach Specialist, UW Madison Division of Extension, Farm Management Program