Developing Effective Protocols to Protect Farmworkers from Heat Stress and Illness While Working in Polytunnels.

HIGHLIGHTS: Farmworkers are at high risk of heat-related illness, especially those working in polytunnels. There is a gap in knowledge regarding working conditions inside polytunnels. Polytunnels are prevalent in California's Central Coast region. Recommendations to reduce the risk of heat-related illness among workers in polytunnels were formulated.

ABSTRACT: Polytunnels-also known as hoop houses-are used worldwide to grow certain crops year-round, primarily to protect plants from precipitation and cool temperatures. Farmworkers may be at increased risk in polytunnels due to higher temperatures and relative humidity. In the Central Coast region of California, polytunnels are commonly used to grow berries and other crops, but information on measures used to reduce heat stress in farmworkers working in polytunnels or how many workers are potentially exposed to these conditions is scarce. The purpose of this study was to: (1) estimate the area under polytunnels and the number of workers in them in California's Central Coast region; (2) assess current practices to manage heat and protect workers in polytunnels; and (3) use this information to develop proposed best practices for protecting farmworkers in polytunnels. Using satellite imagery and crop production records, the area under polytunnels in the region was estimated at 5,162 ha with a conservatively estimated 46,000 farmworkers. Through key informant interviews, we found that farms are generally following OSHA worker safety regulations. However, additional measures may be needed to protect workers because environmental conditions inside polytunnels are variable and difficult to predict. For instance, wet bulb globe temperature would be a more accurate measure of heat stress risk than temperature alone. We propose recommendations that follow the hierarchy of controls to reduce the risk of heat-related illness among workers inside these structures.