The risk of heat-related accidents at work has decreased in Spain over recent decades

Extreme heat and cold are associated with a higher number of occupational accidents, but between 1989 and 2019 the risk of medical leave in Spain on days of extreme heat decreased from 19% to 13%, compared to days of moderate temperatures. This is the key finding of a study led by the Barcelona Institute for Global Health (ISGlobal), a center supported by the “la Caixa” Foundation, and published in Environment International. The research suggests that workers in Spain have been adapting to rising temperatures, possibly due to the Law on Occupational Risk Prevention implemented in 1997.

This law mandated routine inspections to ensure compliance with occupational health regulations, strengthened workers‘ rights to protective measures and training, and encouraged the creation of safety action plans in high-risk enterprises.

The study also reveals that heat adaptation has not been equal across all groups. Workers in the agriculture and hospitality sectors remain most vulnerable to heat-related injuries, which may result from lack of sleep, fatigue, dehydration, reduced psychomotor performance, and loss of concentration or alertness due to heat stress during work hours.

Working in Spain in summer

Studying the relationship between environmental temperatures and occupational accidents is particularly relevant for Spain due to “its relatively high summer temperatures, its economic cycles with intense and prolonged recessions, its climatic and socioeconomic diversity, its precarious working conditions and a significantly faster temperature increase than the global average,” says Constanza Vielma, ISGlobal researcher and first author of the study.

The analysis associated the average temperature and sick leave due to occupational accidents in 48 provinces of Spain over 32 years, from 1988 to 2019. This period includes years before the Law on Occupational Risk Prevention, the recessions of 1992–1993 and 2008–2013, the economic and immigration boom of 2000–2007, and the pre-pandemic economic recovery of 2014–2019. In total, the study covered more than 22 million occupational accidents.

Heat had a greater overall impact than cold

The team found that the temperatures at which the fewest workplace accidents occur in Spain are between 10 and 12ºC. Consequently, they considered that the increase in the number of occupational accidents occurring outside this optimal temperature range was related to either cold or heat.

Using this method, they estimated that 671,000 occupational accidents over the entire study period were due to non-optimal temperatures, i.e. an average of 20,900 accidents per year, accounting for 3% of all work-related accidents. However, the number of accidents attributable to heat or cold has steadily decreased since 1989.

Specifically, 2.7% of all occupational accidents could be attributed to heat, while only 0.3% were attributed to colder temperatures. This greater impact of heat versus cold occurred in all sub-periods analyzed.

The vulnerability of the Spanish hospitality industry

The research team identified several groups with increased vulnerability to occupational accidents:

Workers in agriculture, hospitality and construction were shown to be the most vulnerable to extreme heat, with particularly high risks in agriculture and hospitality. In the period from 2015 to 2019, these sectors had a relatively high risk of occupational accidents due to extreme heat (17% and 21%, respectively), compared to the overall risk for all workers (13%). It should be noted that the study does not include non-contract workers, who are even more vulnerable to all kinds of risks due to the lack of regulation surrounding their working conditions. The steady increase in the proportion of workers in tertiary services (including hospitality) over the last three decades could explain the increase in heat-related occupational accidents in this sector.

Vielma believes that “it is imperative to understand and address the unique vulnerabilities faced by Spanish hospitality workers in the context of rising temperatures, and to consider them alongside other groups traditionally vulnerable to heat, such as workers in agriculture and construction.”

Male workers, those under 35 years of age and those with less than one year of experience had a higher risk of occupational accidents in extreme heat than their counterparts. A possible explanation is the higher proportion of men, and especially young men, in physically demanding outdoor jobs that are more exposed to extreme temperatures. Additionally, evidence suggests behavioral differences between genders, with women more likely to adopt preventive measures and generally more aware of temperature-related occupational hazards.

The research also shows that workers in Spanish provinces with a higher percentage of people holding higher education degrees, were less vulnerable to extreme heat. The researchers suggest that higher education levels may improve workers’ ability to recognize and prevent occupational hazards; that jobs in these provinces are on average less risky (skilled); and, that the population in these areas may have better underlying health.

For extreme cold, women, people over 55 years of age and non-manual workers (those in managerial, technical, tertiary, clerical, office, counter, catering and hospitality, health, security and service occupations) were at higher risk of sick leave, possibly due to a higher risk of respiratory illness in indoor workplaces.

Preventive measures are needed

The study’s findings suggest that Spanish workers have gradually adapted to high temperatures. However, “during the warm months, preventive measures are needed for traditionally exposed workers (agriculture and construction), as well as for non-traditionally vulnerable sectors (hospitality) and young, male and less educated workers,” concludes Joan Ballester Claramunt, principal investigator of the European Research Council (ERC) EARLY-ADAPT project and senior author of the study.

“For vulnerability to cold, specific measures should target women, older adults, and tertiary service workers, especially in colder regions.” Addressing temperature vulnerability would improve worker safety, reduce accidents and bring economic benefits.

The study also highlights that the health effects of heat are influenced by inequalities between provinces and social determinants. Workers in highly exposed jobs, such as agriculture, construction and hospitality, are disproportionately at risk of accidents during summer. These jobs are more common in less economically developed, southern, and therefore hotter, regions of Spain.

For Ballester, “both research and policy initiatives are needed to address the inherent inequalities between and within countries.”

The results of this study will be incorporated into the Forecaster.health platform to create the first early warning system on the impact of temperature on occupational accidents in Spain and at European level. The tool already allows users to enter the date and the population subgroup for which they would like to receive actual predictions of temperature-related health events (mortality for now) within up to two weeks.