How to Mitigate Heat Stress
High temperatures are a common occurrence particularly in the Southwestern United States and workers in many outdoor agricultural operations are daily exposed to conditions leading to heat stress. While the high temperatures cannot be changed, steps can be taken to minimize heat stress of workers. Following is a brief list of how to mitigate heat stress:
- Help learn workers about how the body regulated its temperature and how heat dissipation affects the body's water supply (See the 12 key points to know about heat stress below).
- Scheduling strenuous jobs in full sun during early morning hours when it is cooler.
- Provide shade structures to reduce direct exposure from the sun. Shade structures reduce air temperatures and are ideal for stationary work such as filling pots with media, planting or transplanting container plants.
- Allow a period of acclimation for workers not used to working in high temperatures.
- Provide a fan in stationary work areas when possible. Moving the air can bring additional relief from high temperatures.
- Scheduling shorter durations of exposure to heat is preferable to fewer, longer exposures.
- Provide easy access to water (igloo, water fountain, back- or waist mounted hydration systems, personal water container). 60
12 Key Points to Know About Heat Stress
Heat stress is a build-up of heat in the body. Heat injury or illness is a disruption of physical or mental functions caused by the body's response to heat stress.
- Heat exhaustion is an acute heat injury with hyperthermia caused by dehydration. Early symptoms can include headache, dizziness, weakness, and irritability.
- More advanced symptoms of heat exhaustion include pale and clammy skin, confusion, loss of coordination, upset stomach, vomiting, and fainting.
- Insufficient fluid in the body is the #1 cause of daytime fatigue.
- Most people are chronically dehydrated and start their workday with a fluid deficit.
- The single best measure for reducing risks of heat stress is to drink water frequently throughout the day to replace the fluid that is lost as sweat, as much as 1 quart of water per hour during strenuous work in hot weather.
- Most people do not feel thirsty until their fluid loss is 2 percent or more of body weight and their performance is already reduced. Thirst is an unreliable, usually lagging, indicator for when the body needs water.
- The body operates best at a temperature of 98.6 °F. Both heat and the body's processes for getting rid of excess heat have effects on a person's comfort, performance, accident risk, and long-term health.
- Most of the heat load in a body, when working, comes from its own metabolism. About 3/4s of the stored calories that the body converts to move muscles turn into heat rather than motion.
- Hot weather and high humidity increase the risk of heat injury by slowing down the movement of heat from the body to the environment.
- Increasing blood flow to the body surface for cooling diverts some of the flow that brings oxygen and nutrients to muscles, brain, and other internal organs.
- The loss of fluid as sweat not only decreases the volume of blood to supply internal organs, but also reduces the ability to get rid of excess heat later.
Other Resources to Learn About Heat Stress and Possible Solutions:
Protecting workers from the effects of heat (pdf)
Preventing heat related illness among agricultural workers (pdf)
Skin Cancer Prevention for the Agricultural Employee -
This 16 min. DVD is available in English and Spanish and can be used to train employees on how to prevent the hazards of skin cancer when working in full sun conditions. It can be purchased through CALSMART.