Periods of unusually warm weather can create significant health and safety challenges for businesses. Whether employees are working outdoors, in offices, warehouses, workshops or other indoor environments, higher temperatures can affect comfort, concentration, productivity and, in more severe circumstances, health.
With warmer periods becoming an increasingly important consideration for employers, businesses should understand their responsibilities and have practical arrangements in place for managing heat at work.
A common question during hot weather is: “How hot does it have to be before employees can stop working?”
There is no specific legal maximum workplace temperature and no single temperature at which work must automatically stop. The Health and Safety Executive (HSE) explains that workplaces and working activities vary too greatly for one maximum temperature to be appropriate. This does not mean employers can ignore high temperatures.
Under the Workplace (Health, Safety and Welfare) Regulations 1992, the temperature inside workplaces must be reasonable during working hours. Regulation 7 also requires excessive effects of sunlight on indoor workplace temperatures to be avoided.
The Management of Health and Safety at Work Regulations 1999 also require employers to assess risks to workers and introduce suitable controls. The HSE specifically identifies workplace temperature as a risk that should be considered for both indoor and outdoor work.
Therefore, the important question is not simply “What does the thermometer say?” but:
“Is the temperature creating a risk to the health, safety or welfare of our employees and are we doing enough to control that risk?”
Two employees working at the same air temperature may experience very different levels of heat exposure. The HSE identifies six important factors when considering thermal comfort:
For example, an office employee working at a desk in an air-conditioned environment will face very different risks from an employee undertaking strenuous manual work outdoors in direct sunlight.
Similarly, PPE can significantly increase the risk. Protective clothing may restrict the body’s ability to lose heat through sweating and evaporation. This is why employers should avoid relying on a particular temperature as their only trigger for action.
Heat stress occurs when the body’s normal methods of controlling its internal temperature begin to struggle or fail.
The risk can increase where employees undertake physically demanding work, work in humid conditions, wear restrictive PPE or protective clothing, work close to heat-producing equipment, or spend extended periods in direct sunlight. Early recognition is particularly important. According to the HSE, symptoms associated with heat stress can include:
At the most serious end of the scale is heat stroke. Symptoms can include confusion, convulsions and loss of consciousness and the condition can be fatal if it is not recognised and addressed quickly.
Employers should therefore ensure employees and managers understand the warning signs and know how to raise concerns.
Employers should consider high temperatures as part of their workplace risk assessment arrangements rather than waiting until employees become unwell. The assessment should consider the circumstances of the work, including:
The assessment should be reviewed when circumstances change, including during periods of unusually hot weather.
The controls required will depend on the workplace and the level of risk. Employers should prioritise measures that reduce heat exposure rather than relying solely on employees to cope with it.
Where reasonably practicable, businesses can consider:
The HSE specifically recommends measures including fans, ventilation, shading, repositioning workstations and insulating sources of heat.
Where environmental controls cannot adequately reduce exposure, working arrangements may need to change. This could include:
For higher-risk hot environments, the HSE recommends controlling both work rate and the length of exposure.
Dehydration is one of the most obvious risks associated with working in hot conditions. Employees should have ready access to suitable drinking water and should be encouraged to drink regularly rather than waiting until they feel extremely thirsty.
The HSE advises employers managing heat stress to provide cool water and encourage workers to drink frequently in small amounts. Drinking water is also a basic workplace welfare requirement.
Managers should therefore check that water supplies remain easily accessible, particularly for employees working outdoors, remotely or across large sites.
Employees working outside may face additional risks from direct sunlight and solar radiation. Consider providing:
Employers should also remember that hot weather can interact with other workplace hazards. Fatigue, reduced concentration and discomfort may increase the likelihood of mistakes when driving, operating machinery, working at height or undertaking safety-critical activities.
PPE presents a particular challenge.
Employees should not simply remove required PPE because they are hot. Where PPE is necessary to control a significant workplace hazard, removing it may expose the employee to a greater immediate risk.
Instead, employers should consider whether the work can be reorganised, exposure reduced, additional breaks introduced or alternative suitable PPE provided.
The HSE notes that protective clothing and equipment can contribute to heat stress and that specialised cooling systems or breathable protective fabrics may be appropriate in some hot environments.
The HSE advises employers to reassess the risks where workers report or complain about uncomfortable temperatures, agree appropriate actions and act on the findings.
Consultation is particularly useful because employees carrying out the work are often best placed to identify where heat is becoming problematic and which controls are practical.
Managing hot weather is much easier when arrangements are established before a heatwave arrives. Businesses should consider:
Having predetermined arrangements also helps managers make consistent decisions rather than improvising once temperatures have already become uncomfortable.