Following the hottest May Day on record, heatwaves across the country continue with temperatures exceeding 30°C in many areas. As extreme temperatures trigger yellow and amber warnings from the UK Health and Security Agency, some employees are questioning whether they are permitted to work in such heat.
Legally, there is no set minimum or maximum temperature at which people are not allowed to work. However, employers are required to take several steps to ensure employee safety during extreme weather, which can pose health and safety risks.
Government Guidance on Workplace Temperature
Government guidance explains that there is no defined maximum temperature for safe work because many workplaces are hot due to the nature of the work itself, such as bakeries or foundries, rather than seasonal heat.
Employers must adhere to health and safety regulations, including maintaining a comfortable temperature and providing fresh, clean air. Official guidance states: "Employees should talk to their employer if the workplace temperature is not comfortable."
Construction Sites and Outdoor Work
For construction sites, the Construction (Design and Management) Regulations require reasonable temperatures in indoor areas. Outdoor work must be protected from harsh weather, and rest facilities must be kept at an appropriate temperature.
Under the Management of Health and Safety at Work Regulations, employers must assess risks and implement protective measures. The Health and Safety Executive notes: "All workers are entitled to an environment where risks to their health and safety are properly controlled. Heat is classed as a hazard and comes with legal obligations like any other hazard."
Heat Stress and Dehydration Risks
Workers in extreme temperatures may suffer heat stress, where the body's temperature regulation fails, influenced by air temperature, humidity, work rate, and clothing. Symptoms include:
- Inability to concentrate
- Muscle cramps
- Heat rash
- Severe thirst
- Fainting
- Heat exhaustion (fatigue, dizziness, nausea, headache, moist skin)
- Heat stroke (hot dry skin, confusion, convulsions, loss of consciousness)
Heat stress is a year-round concern in some workplaces like manufacturing plants, boiler rooms, laundries, and compressed-air tunnels. Dehydration is also a serious risk. The Health and Safety Executive recommends drinking cool water frequently in small amounts to compensate for sweating, noting that thirst alone is not a reliable indicator of dehydration. It advises: "When working at a high rate in heat stress conditions, workers should drink around 250 ml (half a pint) every 15 minutes."
