There are many heat stress prevention strategies for farmworkers that focus on correcting either individual behaviors (e.g., avoiding caffeinated beverages and bulky sweatshirts) or workplace conditions (e.g., providing shade and regular break periods). Yet, few heat stress-specific health plans take into consideration the conditions of the built and natural environment that farmworkers are returning to at the end of a long day in the fields.

Farmworkers at Risk, Even at Home

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By Gail Wadsworth and Vallerye Mosquera

With funding from University of California Sustainable Agriculture Research and Education Program, CIRS is partnering with Dr. Michael Rios and Vallerye Mosquera from UC, Davis, and Luis Magaña from the Organizacion de Trabajadores Agricolas de California, to complete a community-based risk assessment tool for heat stress.  This tool is unique in that it is focusing on the risk of heat stress to farmworkers within their communities.  In other words:  off the farm.

It is well established that agricultural work is dangerous.  California has the largest number of crop workers in the US, and thousands lose work time to occupational injury or illness every year.  On average, each year, 3,360 of the state’s farm laborers experience a permanent, on-the-job, disabling injury or illness. [i] In addition to the well-known risks of farm work such as accidents involving machinery, pesticide exposure and musculoskeletal injury, workers also face the threat of heat exposure that can result in illness and death.  Heat illness cases on California farms occur at a rate three times higher than in all of the state’s industries combined. [ii] Cal-OSHA’s records of heat illness investigations from 1990-2008 demonstrate that an absolute majority of fatal cases (58%) occurred in agriculture but farm employment comprises less than 15% of total employment for those industries, such as agriculture, construction and manufacturing, in which verified cases of occupational heat illness fatalities had occurred. [iii]

In July of this year, six deaths related to heat stress were under investigation, two of which were farm workers.  One of these deaths was a 47-year-old worker in Blythe California who died after operating a tractor in 102-degree heat. Relevant to these data is the suspicion that the number of heat-related deaths in the Central Valley of California may be underreported.  The heat wave of 2006 resulted in 50 reported deaths in the Central Valley and 140 deaths statewide. But some estimates indicate that more than 600 heat-related deaths may have occurred over the seventeen days of extreme heat.  According to Margolis, et al (2006), in that particular heat wave, 99% of the cases lived in zip codes where over 50% of residents were living below the poverty level. [iv] This statistic is significant as it reflects community attributes and the ability of residents, including farmworkers, to obtain services they need in the case of an illness.

Extensive research done by California Department of Health and the Natural Resources Defense Council showed a significant increase in visits to emergency rooms and hospitalizations for cardiac illnesses among Latinos statewide during the 2006 heat wave. [v] The implications of this extensive research are that many of the deaths due to heat illness may have been attributed to factors other than heat and will not be reported as heat related fatalities even though they may be.


While these statistics report mortality rates for individuals due to heat illness, they do not account for many of the problems leading to heat-related mortality that are environmental in nature and can be found in non-occupational settings where farmworkers live. In fact, some studies have stressed the "accumulation" effect of heat. A detailed look at community vulnerability to heat-related morbidity and mortality showed that there are interrelated factors that combine to increase vulnerability of populations and individuals. Given that climate change will result in higher average temperatures, one study on the topic concluded that “A community’s overall vulnerability reflects that of its constituent populations, as well as the capacity of its public health and emergency response infrastructure... factors that may influence both biologic response and exposure." [vi]

If factors within the community are such that farmworkers are not able to dissipate internal heat (lack of shade, no air conditioning, cool water) or unable to access necessary services (no telephone or transportation), these must be considered in addition to on-farm exposure factors. According to Tracie White (2007), "It can take only 48 hours of uninterrupted exposure to intense heat before the body’s defenses begin to break down.... The longer a heat wave continues the more susceptible the body becomes to illness." [vii] The 2006 heat wave is an example of what happens when there is no relief from the heat.

When considering heat stress morbidity and mortality among farmworkers, research must be done on factors in the community that either increase or contribute to the risk to these workers; including the ability to cool off after work. Thus, the ongoing research focuses on the social ecological factors that can lead to heat-related mortality that disproportionately affect farmworkers. These include factors that situate individual health in relation to intrapersonal, sociocultural, policy, and physical-environmental factors. [viii] Social ecology is an appropriate model for disease prevention and “provides a way of thinking about the planning of health promotion interventions that places a spotlight on the relationship between the environmental and behavioral determinants of health.” [iv] Therefore the relative health of individuals is shaped by a variety of institutional and policy sectors that determine how communities are planned, built, and whether support systems such as transportation, water quality, and medical response, among other forms of infrastructure, are put in place.

By identifying and assessing environmental and behavioral determinants in residential sites and community settings, the current CIRS research project will draw attention to existing environmental and policy barriers within these communities.  At the same time we hope to identify appropriate strategies to improve farmworker and rural community well-being that have implications for local policy and resource development.


[i] Workers Compensation Insurance Rating Bureau of California, “Exhibit 1,” Column D, Number of Permanent Indemnity Claims w/AWW,  2006 Average Wage and Frequency by Classification Projections for Policy Year 2006, April 22, 2005, San Francisco, CA; cf.

[ii] Fitzsimmons K Harrison R, “Tracking of Occupational Heath-Related Illness in California, 2000-2007,” Western Regional Epidemiology Network Conference, May 14, 2008.

[iii] Cal-OSHA, Heat-related accident investigations, 1990-2008, December 5, 2008.

[iv] 2006 Margolis, HG, A Gershunov, T Kim, P English and R Trent.  California Heat Wave High Death Toll: Insights Gained from Coroner's Reports and Meteorological Characteristics of Event.

[v] 2006. Dolney TJ, Sheridan SC. The relationship between extreme heat and ambulance response calls for the city of Toronto, Ontario, Canada Environ Res 101(1):94–103; 2006. Mastrangelo G, Hajat S, Fadda E, Buja A, Fedeli U, Spolaore P. Contrasting patterns of hospital admissions and mortality during heat waves: are deaths from circulatory disease a real excess or an artifact? Med Hypotheses. 2006;66:1025–1028.

[vi] Climate Change Public Health Impacts Assessment and Response Collaborative, California Department of Public Health and the Public Health Institute

[vii] 2007. Tracie White. Silent inferno California's summer disaster: 138 dead.  Stanford Medicine Magazine, Spring 2007

[viii] 1997. J. F. Sallis and N. Owen 1997, Sallis, James F., and Neville Owen. Ecological Models of Health Behavior. In Health Behavior and Health Education: Theory, Research, and Practice, eds. Karen Glanz, Barbara K. Rimer and Frances Marcus Lewis, 462-484. San Francisco: jomsey-Bass.

[ix] Alcalay, R., and R.A. Bell. 2000. Promoting Nutrition and Physical Activity through Social Marketing: Current Practices and Recommendations. Davis: Center for Advanced Studies in Nutrition and Social Marketing, University of California, Davis. P. 22.

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Vallerye Mosquera is a master’s student in Community and Regional Development at UC Davis. At UCD, she has served as a graduate student researcher for a study of immigrant and refugee serving organizations in the Sacramento region. She is also a part-time Bilingual Sexual Assault Victim Advocate for the Sexual Assault Domestic Violence Center in Yolo County. Prior to attending UC Davis, her work experience included outreach and environmental advocacy to Spanish-speaking communities in the United States and Latin America. Between 2005 and 2006, Vallerye earned a Bachelor’s degree in biology from the New College of Florida which led to a Fulbright research scholarship in Quito, Ecuador where she was responsible for evaluating social and environmental policies related to solid waste disposal. Mrs. Mosquera is fluent in Spanish and Portuguese.


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