Extreme heat and work injuries in Kuwait's hot summers

Hot, desert Gulf countries are host to millions of migrant workers doing outdoor jobs such as construction and hospitality. The Gulf countries apply a summertime ban on midday work to protect workers from extreme heat, although without clear evidence of effectiveness. We assessed the risk of occupational injuries associated with extreme hot temperatures during the summertime ban on midday work in Kuwait.

We collected daily occupational injuries in the summer months that are reported to the Ministry of Health's Occupational Health Department for 5 years from 2015 to 2019. We fitted generalised additive models with a quasi-Poisson distribution in a time series design. A 7-day moving average of daily temperature was modelled with penalised splines adjusted for relative humidity, time trend and day of the week.

During the summertime ban, the daily average temperature was 39.4°C (±1.8°C). There were 7.2, 7.6 and 9.4 reported injuries per day in the summer months of June, July and August, respectively. Compared with the 10th percentile of summer temperatures in Kuwait (37.0°C), the average day with a temperature of 39.4°C increased the relative risk of injury to 1.44 (95% CI 1.34 to 1.53). Similarly, temperatures of 40°C and 41°C were associated with relative risks of 1.48 (95% CI 1.39 to 1.59) and 1.44 (95% CI 1.27 to 1.63), respectively. At the 90th percentile (42°C), the risks levelled off (relative risk 1.21; 95% CI 0.93 to 1.57).

We found substantial increases in the risk of occupational injury from extremely hot temperatures despite the ban on midday work policy in Kuwait. 'Calendar-based' regulations may be inadequate to provide occupational heat protections, especially for migrant workers.