Heat and cold at work: Occupational accidents and apparent temperature in the primary and construction sectors across five spanish provinces

This study aims to evaluate the impact of Apparent Temperature (AT), a biometeorological index that estimates perceived thermal sensation, on occupational accidents in five Spanish provinces, while separately analyzing accidents in the primary sector (agriculture, forestry, livestock farming, and aquaculture) and construction. An ecological time-series study was conducted over a 17-year period. A Generalized Additive Model combined with a Distributed Lag Non-linear Model using a quasi-Poisson distribution was applied to estimate the association between daily occupational accidents and AT. In the two southern provinces, occupational accidents increase as temperature rises. In contrast, in Ávila, Cantabria, and Pontevedra, the relative risk (RR) of occupational accidents increases at thermal extremes (both low and high AT), although the effect is statistically significant only at low temperatures. In the primary sector, accidents in Cantabria and Pontevedra (the two northern coastal provinces) increase with AT. In Cantabria, the maximum number of accidents occurs at 34°C, where the risk is 1.73 times higher than at 14°C (the AT associated with the minimum number of occupational accidents [ATma]). In Pontevedra, the maximum is reached at 38°C, with a risk 1.48 times higher than at 19°C (ATma). Occupational accidents in construction are statistically significantly associated with AT only in Seville, reaching the highest risk at 40°C, where the risk is 1.38 times higher than at 21°C (ATma). The pattern of association between AT and workplace accidents varies across provinces, which may be influenced by climatic characteristics that, in turn, determine the type of professional activity carried out at different times of the year.