A Multi-Level Approach to Heat-Related Illness Prevention for Agricultural Workers

Heat risks are preventable, yet are the cause of injury, illness, and death, particularly affecting outdoor workers. Heat events are predicted to be more frequent and occur for longer periods of time, and agricultural communities are looking for solutions. Few studies have examined approaches to heat illness that involve solutions for individuals, workplaces, and communities.

Project Overview

This project is developing and evaluating a multi-level approach to prevent heat illness by providing training tools and resources for employers, supervisors, and workers. The Heat Education & Awareness Tools (HEAT) toolkit was developed in collaboration with agricultural workers, growers, communities, educators, and other stakeholders. Field studies were conducted with workers with multiple farm partners, assessing the HEAT intervention and work, environmental, and housing conditions. Our research recorded workers’ heat exposure, tasks, signs of heat illness symptoms and biometrics. Also studied in real-life conditions is the possible association between heat strain during the workday and hot housing conditions.

Findings to Date

  • Results from a pre/post knowledge assessment of 83 workers showed that our HEAT training:
    • Improved knowledge scores 4x more than those without the HEAT training.
    • Improved most in the areas of risk factors and treatments.
  • Our physiological measures for heat strain (heart rate and core body temperature) showed greater heat strain with high effort and lower heat strain with older age.
  • Results from participants self-reporting heat illness symptoms found associations with higher heat exposure, 10+ years agricultural work, not being an H-2A guest worker, and walking > 3 min to get to the toilet at work. 
  • We found variation in farmworker housing ambient conditions and reduced sleep duration in barrack-type housing.

Next Steps

We are currently evaluating the relationship between ambient conditions during sleep in farmworker housing and sleep duration, and whether hot housing conditions may modify the effect of heat strain when working. As part of this research, activity monitor (sleep) data have been cleaned, the relationship between measured and self-reported sleep duration described, and preliminary analyses conducted. For our 2022 summer field work on shade and heat exposure, we are in the process of analyzing these data to inform best practices. This coming year we will be producing peer-reviewed manuscripts, infographics, and accessible materials in English and Spanish describing these study findings.

Our research team continues to provide technical input during recent Washington and Oregon rulemaking public comment periods. Also, we continue to work with PNASH’s Outreach Core to disseminate information on heat illness prevention, results of analyses, and the promotion of the HEAT Toolkit. Priorities for our next step dissemination are finding ways to engage trainers and small farms and expanding our reach to other states. Future research is needed in developing evidence-based best practices for acclimatization and optimal sleeping patterns in group housing.

Partnerships and Advisories

  • Washington State University, AgWeatherNet Program



Chavez Santos E, Spector JT, Egbert J, Krenz J, Sampson PD, Palmández P, Torres E, Blancas M, Carmona J, Jung J, Flunker JC. The Effect of the Participatory Heat Education and Awareness Tools (HEAT) Intervention on Agricultural Worker Physiological Heat Strain: Results from a Parallel, Comparison, Group Randomized Study. BMC Public Health. 2022 Sep 15;22(1):1746. 

Flunker JC, Zuidema C, Jung J, Kasner E, Cohen M, Seto E, Austin E, Spector JT. Potential Impacts of Different Occupational Outdoor Heat Exposure Thresholds among Washington State Crop and Construction Workers and Implications for Other Jurisdictions. International Journal of Environmental Research and Public Health. 2022 Sep 14;19(18):11583. 

Egbert J, Krenz J, Sampson PD, Jung J, Calkins M, Zhang K, Palmández P, Faestel P, Spector JT. Accuracy of an Estimated Core Temperature Algorithm for Agricultural Workers. Archives of Environmental & Occupational Health. 2022;77(10):809-818.

Marquez D, Krenz JE, Chavez Santos É, Torres E, Palmández P, Sampson PD, Blancas M, Carmona J, Spector JT. The Effect of Participatory Heat Education on Agricultural Worker Knowledge. J Agromedicine. 2022 Apr 17:1-12. doi: 10.1080/1059924X.2022.2058667. Epub ahead of print.

Krenz J, Chavez Santos E, Torres E, Palmández P, Carmona J, Blancas M, Marquez D, Sampson P, Spector JT. The Multi-level Heat Education and Awareness Tools [HEAT] Intervention Study for Farmworkers: Rationale and Methods. Contemporary Clinical Trials Communications. 2021 Jun 8;22:100795.

Report A Multi-Level Approach to Heat-Related Illness Prevention for Agricultural Workers 

Findings as reported at the end of year five are included in our annual report.

Principal Investigator: June Spector, MD, MPH, Associate Professor, Environmental and Occupational Health Sciences, University of Washington

NIOSH Funding Period 2016-2022