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Working temperatures – when is it too hot to work?

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The summer of 2018 is already being compared with the long, hot scorcher of 1976. Records have been broken across the UK, the words hose-pipe ban' are being whispered, and we're all suffering from sleep deprivation due to night-time temperatures that are in the high teens. It's hot, it's sticky, and, unless you're at the beach, it sucks the energy right out of you. The question is, when does it get too hot to work? Are employers legally required to keep your workplace within a certain range, and can you knock off work early if it gets too hot?

The simple answer is no. There isn't actually any legal requirement for employers to let you go home when it gets hot. The only guidance you'll find on the standard Gov.UK page on workplace temperatures is that all indoor workplaces must be reasonable'. There is no law stating what the minimum or maximum working temperatures are, so it's really down to the discretion of the employer. The guidance numbers range from a minimum of 16°C, or 13°C if employees are engaged in physical work. But they're exactly that - just guidance numbers. They're not enforceable by law.

More detailed guidance comes from the Health and Safety Executive, who state that employers have a duty of care towards their employees and should ensure that:

¥ Temperatures are kept at a comfortable level and that extremes of temperature should be avoided. This is also known as thermal comfort'.
¥ Clean, fresh air should be provided at all times.

The Six Factors

According to the HSE, there are six factors that can be directly related to thermal comfort. Air temperature alone is not an accurate or valid indicator of thermal comfort or, conversely, thermal stress. You need to take into account both environmental and personal factors:

Environmental factors:

¥ Air temperature
¥ Radiant temperature - any heat radiating from warm objects
¥ Air velocity - the speed at which air moves across an employee (for example, still or stagnant air that is artificially heated).
¥ Humidity - humidity levels can be said to be high when they are greater than 80%

Personal factors:

¥ Clothing Insulation - particularly relevant if you are required to wear PPE during your work
¥ Metabolic heat - the amount of heat given off during physical activity.

It can be very difficult to legislate on any of these, particularly personal factors. PPE is often a legal requirement, and metabolic heat will depend on the individual.

However, if environmental factors are giving cause for concern then you may be able to challenge your employer through either your union representative, or via legal representation. Remember, though, that there is no set limit in law so any legal challenges may be difficult. It's probably better to think about mediation rather than litigation.

Take a different approach

Rather than tackling the problem from a temperature point of view, it may be worth looking at it from a different angle - your employer's duty of care to ensure a safe and comfortable working environment. If you feel that your wellbeing is being put at risk due to your working conditions, then you can challenge your employer and ask them to address the situation. This is particularly true if you have underlying health conditions such as asthma that may be exasperated by extremes of heat, humidity, or poor quality air.

It is highly unlikely that you will get an instant response, but by pointing out to your employer that conditions are bad, you may be able to effect changes that will improve the situation later on. If they are unwilling to enter into any kind of dialogue, then you may need to ask a mediator to step in to get both sides talking again. Talk to a legal expert, professional mediator, or your union representative.

It looks like we're going to have a very long, hot summer, and if the temperature keeps breaking records then employers are going to have to look at the conditions their workers are operating in, both inside and outdoors.

Steven Judge Head of Employment Law Department can be contacted on 01323 434416 or email

Steven Judge



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