UK heatwave: When is it too hot to work? Can offices and schools close?

The UK is in the grips of a heatwave with schools and offices baking as the mercury continues to climb to sizzling highs.

Temperatures have reached 40C for the first time on record in the UK this week, leaving many employees sweating into their laptops, but how hot does it need to be before workplaces shut?

And is there a maximum temperature before sweltering school pupils are sent home in the heat?

Read more: UK heatwave: How hot is too hot?, Yahoo UK, 4-min read

Workplace guidance during a heatwave

Last year, during another UK hot weather spell, the TUC urged employers to make sure their staff are protected from the sun and heat after the UK Health Security Agency (UKHSA) issued a health alert.

While you might currently be baking in the boardroom, the idea that you can demand your boss send you home from work when it reaches a certain temperature is actually a myth in the UK.

Watch: Weather: Parts of the UK experiencing heatwave, Met Office says

However, while the Health and Safety Executive (HSE), under the Workplace Regulations of 1992, may not state a specific temperature, it does say that conditions in which employees work must be kept at a reasonable and comfortable level.

For example, if employers are calling people into the office they must assess the risk of those having to travel on stuffy public transport, and consider whether allowing their employees to work at home will be less harmful.

Or, if office temperatures become hot and uncomfortable, employers should consider adding fans to help lower the temperature of the room.

"Employers are also legally required to consider each employee's particular circumstances such as if they have a health condition that will be put at risk if they are working in an environment that is too hot," the spokesperson adds.

Read more: What happens to your body when you get too hot?, Yahoo Life UK, 4-min read

How can you keep cool in the office?

The HSE does issue advice as to what you can do to “improve thermal comfort in your workplace”.

Employees can:

• Dress more casually (with permission) or remove certain items of clothing to keep cool.

• Wear high-factor sun cream and take regular breaks in the shade if you work outside.

• Use a fan to increase airflow in the space in which you work.

• Drink plenty of water, taking care to avoid caffeine or fizzy drinks in order to stay hydrated.

• Take more frequent breaks than you usually would, somewhere cool.

• Work away from an area that is in direct sunlight if you work in an office or at home.

Employers can:

• Carry out a risk assessment (which they are required to do by law) and introduce any necessary or preventative measures.

• Give employees frequent rest breaks.

• Provide access to free water for all employees no matter the work environment.

• Try and reschedule outdoor work to times of the day that are cooler.

• Add in shaded areas where employees may be working.

• Allow employees to dress more casually if it means they will stay cooler.

• Consider whether work can be done from home, to avoid employees travelling on public transportation.

• Make sure that rooms in which employees are working are well ventilated and at a comfortable temperature.

• Educate employees on the signs of heat exhaustion and what they can do to keep cool.

The HSE has further tips and advice on what workers can do to try to stay cool in the heat.

Read more: Heatwave insomnia: 32 tips and tricks to help you sleep during hot weather, Yahoo Life UK, 8-min read

Is there a temperature schools should close?

Soaring classroom temperatures inside combined with baking heat outside could leave some parents questioning whether their children could be sent home in the heat.

But schools are actually subject to the same regulations as workplaces.

This means that although there is a minimum temperature a building must be for work or study to take place, there is no maximum.

Your child's school is responsible for the day-to-day welfare of your children on their grounds, adhering to the Health and Safety Executive (HSE) guidelines.

The government has also produced some guidelines for schools about what to do in a heatwave.

Protecting children indoors

• Open windows as early as possible in the morning before children arrive, or preferably overnight to allow stored heat to escape from the building.

• Almost close windows when the outdoor air becomes warmer than the air indoors.

• Use outdoor sun awnings if available, or close indoor blinds or curtains, but do not let them block window ventilation.

• Keep the use of electric lighting to a minimum.

• Switch off all electrical equipment, including computers, monitors and printers when not in use.

• If possible, use those classrooms or other spaces which are less likely to overheat, and adjust the layout of teaching spaces to avoid direct sunlight on children.

• Oscillating mechanical fans can be used to increase air movement if temperatures are below 35°C – at temperatures above 35°C fans may not prevent heat-related illness and may worsen dehydration.

• If necessary, consider rearranging school start, finish, and play times to avoid teaching during very hot conditions.

• Encourage children to drink plenty of cool water.