The National Weather Service has graphical forecasts for many weather variables including heat index and wet bulb globe temperature which can be used to evaluate risk of heat stress. These predictive tools may be utilized to evaluate the risk of heat stress up to one week in advance and may aid in planning of field activities.

• Heat index: describes the apparent temperature based on air temperature and relative humidity in shady locations.
• Wet bulb globe temperature: incorporates air temperature, relative humidity, solar radiation, and wind speed. May be more representative of field-based working conditions.

To access these graphical forecasts, visit https://digital.weather.gov/ and select either Wet Bulb Globe Temperature or HeatRisk experimental (i.e., heat index) from the drop-down menu. Zoom in to your location by holding your cursor over the area and scrolling with your mouse, or use the provided Zoom and movement tools in the upper left of the graph.

Article By: The Rutgers Farm Health and Safety Working Group: Kate Brown, Michelle Infante-Casella, Stephen Komar and William Bamka

The outdoor nature of crop and livestock production exposes farmers and farm workers to variable weather conditions. During the summer months, periods of high heat can increase the risk of heat stress and heat-related illness.  

Farm employers can proactively reduce the risk of heat stress in farmworkers by providing training to all employees on heat exposure risks, prevention actions, and first aid. In this way, employees will be able recognize symptoms of heat-related illness in themselves and others, take preventative steps to mitigate risk of heat stress, understand personal risk factors, and know how to respond in case of emergency.  

• For resources to aid in worker training, check out the comprehensive Occupational Safety and Health Administration (OSHA) website on Working in Outdoor and Indoor Heat Environments. 

Once training is complete, farm employers may wish to reinforce training with posters in high traffic areas such as the common break area, near farmworker housing, or at the central display location. OSHA has developed a ‘Prevent Heat Illness at Work’ poster for this purpose (available in English and Spanish) as well as a pocket-sized pamphlet (available in 21 languages) for distribution among farmworkers.  

USDA Photo by Lance Cheung.

The Rutgers Farm Health and Safety Working Group, in partnership with New Jersey Farm Bureau, invites you to a two-part webinar series titled “Don’t Sweat Heat Stress in Agriculture”. The first webinar will take place tonight!

• Wednesday, June 5 from 7:00-8:00 PM
  • An introduction to heat stress issues in agriculture. We will also share tools farmers can use to evaluate heat risk and recommended resources for guidance on heat stress prevention.
• Wednesday, June 12 from 7:00-8:00 PM
  • An overview on signs of heat stress and corresponding first aid, as well as strategies for heat stress prevention. A panel of farmers will discuss their currently used strategies for employee management during periods of high heat.

You must register to attend these webinars by visiting https://go.rutgers.edu/heat-stress-in-ag. 

Questions? Contact Kate Brown, County ANR Agent with RCE-Somerset County, at 908-526-6293 x4 or kbrown@njaes.rutgers.edu.

Evaporation of sweat from skin is the body’s primary mode of temperature regulation on hot days. Clothing can impact heat and sweat production, as well as the rate of evaporation, so clothing decisions are important to prevent heat stress.  

Photo credit: Joe Proudman , UC Davis Western Center for Agricultural Health and Safety

Choose lightweight, loose-fitting clothing made of a breathable fabric like cotton which allows sweat to evaporate and air to move across the skin, cooling the body. Choose light-colored clothing, which reflects heat, and a wide-brimmed hat to shade around the head.

Generally, less clothing is desirable in hot environments, except when the air temperature is greater than 95°F or a person is working in the direct sun. In these cases, covering exposed skin can reduce the risk of heat stress. 

Personal protective equipment like gloves, respirators, and coveralls can significantly increase metabolic heat production, reduce evaporation of sweat, and increase the risk of heat illness. Schedule all tasks requiring PPE for cooler times of day such as morning and evening.  

New workers are vulnerable to heat-related illness because they have not acclimatized to working in the heat. Acclimatization is a physiological process that occurs when exposure to heat takes place gradually over an extended period. Once acclimatization is achieved, working in the heat results in production of a more dilute sweat (lower salt content) and less of an increase in heart rate and body temperature, reducing the risk of heat-related illness.  

One approach to achieving acclimatization is to limit occupational heat exposure to one-third of the workday during the first and second days, one-half of the workday during the third and fourth days, and two-thirds of the workday during the fifth and sixth days.

Photo credit: California Farm Bureau Federation

Additional Strategies For Worker Heat Acclimatization 

• Schedule new workers for shorter time periods in the heat, separated with frequent break periods. 
• Train new workers about heat exposure, symptoms of heat-related illness, and the importance of rest and hydrating with water even during non-work hours. 
• Monitor new workers closely for any symptoms of heat-related illness. 
• Use a system where new workers do not work alone. 
• If new workers talk about or show any symptoms, allow them to stop working. Administer first aid. Never leave someone alone who is experiencing heat stress symptoms. 

These increased precautions should last for 1–2 weeks. After that time, new workers should be acclimatized to the heat and can safely work a normal schedule. The acclimatization procedure should be repeated if a person misses workdays after days off due to illness, vacation, or other reasons for missing one week or more of job duties. For more information on acclimatization, check out this resource from NIOSH. 

The Rutgers NJAES factsheet on “Preventing Heat Stress in Agriculture” has been updated and is now available at https://njaes.rutgers.edu/FS747/. The factsheet provides basic knowledge about heat stress, first-aid treatment, and preventative measures that are important to both agricultural employers and workers. As the temperatures warm up, it’s time to get prepared for working in the heat!