The Hidden Health Costs of Extreme Heat Exposures on Outdoor Workers in the California Central Valley

California accounts for 16% of U.S. crop production, employing over 450,000 people in agriculture, two-thirds of which are of Latino ethnicity. The California Central Valley alone exports approximately $11 billion worth of agricultural commodities to foreign markets. Despite Occupational Health and Safety Administration (OSHA) regulations, heat-related illnesses and deaths have risen in past years. Occupational heat exposure is a ‘pernicious impact’, or an impact that requires trade-offs between what is generally assumed and valued as part of society (i.e., lower cost yet high-quality food) and what is healthy for an individual or population. Rising temperatures may have a direct impact on the economy through outdoor worker health and productivity, yet minimal research exists at the intersection of climate extremes, health, and economics, and/or the past and present trends of said interactions. Hence, the aim of this research is to integrate climate data and heat stress exposure assessments in the California Valley with agricultural productivity output. This approach entails transdisciplinary collaboration and data alignment across climate, social, economic, and health sciences to provide adaptable and practical solutions.

Agriculture productivity data include crop budgets and the derivation of the labor requirements for each crop, crop prices, production levels and acreage for each crop, and worker compensation scheme. Health-relevant heat indices (wet-bulb and wet-bulb globe temperatures (WBGT); heat index; human heat balance; thermal work limit) will be calculated using California Irrigation Management Information System (CIMIS) sub-daily station data, including measured solar radiation. Projected climate data will be provided through 25km resolution CMIP5 models for California. OSHA thresholds will be applied to WBGT estimates to determine the slowing or stoppage of work, and subsequently fed into agricultural productivity models to determine units of product lost due to decreased worker productivity. These new data will augment the ability to model the impacts of extreme heat on worker productivity as a co-variate in economic loss, thus enhancing adaptable and practical decision support in specific agricultural sectors. The analysis will highlight the serious trade-offs between future extremes, health, and labor productivity, and provide adaptive coping mechanisms for outdoor workers, in turn increasing the value of extreme impact analysis.