Occupational fatal injuries and extreme Temperatures: A case-crossover study in Italy

Climate change is increasing extreme heat events worldwide, with substantial health impacts. Workers are particularly vulnerable to heat exposure due to their limited ability to avoid exposure during physically demanding tasks. Previous studies have documented associations between high temperatures and non-fatal occupational injuries in Italy. However, no nationwide study has yet assessed the association between extreme temperatures and fatal occupational injuries.

To investigate the association between exposure to extreme temperatures and the risk of fatal occupational injuries in Italy.

A time-stratified case-crossover model was constructed on occupational fatal injuries reported to the Italian Workers' Compensation Authority (INAIL) between 2014 and 2019, with exposure measured by the Universal Thermal Climate Index (UTCI). Conditional logistic regression with distributed lag non-linear model was used to estimate the association. The odds ratios (ORs) curve was calculated relative to a reference UTCI value corresponding to thermal comfort conditions and a single point measure was calculated comparing the 99th with the 75th percentile. Stratified analyses were performed across demographic and occupational variables.

A clear increase in risk for high UTCI values was found. Compared with the 75th percentile (22.4 °C UTCI), the 99th percentile (31.2 °C UTCI) was associated with an odds ratio of 1.61 [1.22-2.14], corresponding to 84 [9-151] attributable deaths. The association was strongest on the day of exposure and was stronger among men, younger and older workers and in outdoor occupations such as agriculture and construction. Indoor heat producing activities also showed an association.

Extreme heat was associated with an increased risk of occupational death, particularly in agriculture, construction, indoor heat-exposed occupations and vulnerable worker groups. These findings confirm heat exposure as a major preventable occupational hazard and call for urgent, heat-specific nationwide prevention policies in the context of climate change.