Report From NIOSH Examines Heat-Related Deaths Among Crop Workers

June 19, 2008
The June 19 issue of the Morbidity and Mortality Report includes a study conducted by researchers at the National Institute for Occupational Safety and Health (NIOSH) of heat-related deaths among crop workers in the United States.

The report focuses on workers employed in outdoor occupations such as farming, who are exposed to hot and humid environments that put them at risk for heat-related illness or death. The report describes one such death and summarizes heat-related fatalities among crop production workers in the United States during 1992–2006.

During this 15-year period, 423 workers in agricultural and nonagricultural industries were reported to have died from exposure to environmental heat; 68 (16 percent) of these workers were engaged in crop production or support activities for crop production. The heat-related average annual death rate for these crop workers was 0.39 per 100,000 workers, compared with 0.02 for all U.S. civilian workers.

A Tragic Case Study

The NIOSH researchers included a case study from North Carolina that occurred in mid-July 2005. A 56-year-old, male, Hispanic worker with an H-2A work visa (i.e., a temporary, nonimmigrant foreign worker hired under contract to perform farm work) was hand-harvesting ripe tobacco leaves on a North Carolina farm. He had arrived from Mexico 4 days earlier and was on his third day on the job.

The man began work at approximately 6 a.m. and took a short mid-morning break and a 90-minute lunch break. At approximately 2:45 p.m., the employer’s son observed the man working slowly and reportedly instructed him to rest, but the man continued working. Shortly thereafter, the man’s coworkers noticed that he appeared confused. Although the man was combative, his coworkers carried him to the shade and tried unsuccessfully to get him to drink water. At approximately 3:50 p.m., coworkers notified the employer of the man’s condition.

At 4:25 p.m., the man was taken by ambulance to an emergency department, where his core body temperature was recorded at 108°F and, despite treatment, he died. The cause of death was heat stroke.

On the day of the incident, the local high temperature was approximately 93°F with 44 percent relative humidity and clear skies. The heat index was in the range of 86°–101°F
at mid-morning and 97°–112°F at mid-afternoon. Similar conditions had occurred during the preceding 2 days.

The worker had been given safety and health training on pesticides but nothing that addressed the hazards and prevention of heat-related stress. He reportedly only spoke Spanish. Fluids, such as water and soda, were always available to the workers in the field; however, whether the worker drank any of these fluids is unknown.

Preventing Deaths

Data aggregated into 5-year periods by the NIOSH researchers indicated that heat-related death rates among crop workers might be increasing. However, trend analysis did not indicate a statistically significant increase.

Prevention of heat-related deaths among crop workers requires educating employers and workers on the hazards of working in hot environments, including recognition of heat-related illness symptoms, and implementing appropriate heat stress management measures.

Heat-related illnesses range from minor heat cramps or rash to heat exhaustion, which is more serious and can lead to potentially fatal heat stroke. Heat stroke is characterized by a body temperature of greater than 103°F; red, hot, and dry skin (with no sweating); rapid, strong pulse; throbbing headache; dizziness; nausea; confusion; and unconsciousness.

Crop workers might be at increased risk for heat stroke because they often wear extra clothing and personal protective equipment to protect against pesticide poisoning or green tobacco illness (transdermal nicotine poisoning). Employers and workers must be aware that heat-related illness, which can have symptoms similar to pesticide poisoning and green tobacco illness, requires immediate attention.

The high proportion of heat-related deaths among foreign-born workers indicates that training and communications regarding the risk for heat-related illnesses should be provided in the workers’ native language.

Guidance to help agricultural employers establish a heat illness prevention program is available from NIOSH at and information from the National Ag Safety Database on identifying and treating heat stress can be found at OSHA has a Safety and Health Topics page devoted to heat stress and it can be found at

California and Washington state recently have nacted regulations requiring that employers take action to prevent heat-related illnesses and deaths among their workers, including providing training to supervisors and workers and ensuring the availability of fluids. These regulations were prompted by deaths and illnesses in both states in recent years.

The NIOSH researchers advise agricultural employers to develop and implement heat stress management measures that include:

  1. Training for field supervisors and employees to prevent, recognize
    and treat heat illness
  2. Implementing a heat acclimatization program
  3. Encouraging proper hydration with proper amounts and types of fluids
  4. Establishing work/rest schedules appropriate for the current heat indices
  5. Ensuring access to shade or cooling areas
  6. Monitoring the environment and workers during hot conditions
  7. Providing prompt medical attention to workers who show signs of heat illness.

“Employers and workers should be vigilant for signs of heat illness, not only in themselves but in their coworkers, and be prepared to provide and seek medical assistance,” noted the NIOSH team of researchers.

About the Author

Sandy Smith

Sandy Smith is the former content director of EHS Today, and is currently the EHSQ content & community lead at Intelex Technologies Inc. She has written about occupational safety and health and environmental issues since 1990.

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