Code red. Code red. The UK declares the first-ever red alert national emergencyAfter the 2003 heatwave, the UK set up a five-level "heat-health alert system" from 0 to 4. This is the first time the level has been raised to Level 4. The Met Office has also issued the first red extreme heat weather warning. for heat. Today and tomorrow, forecasters expect temperatures to smash records, hitting 40C in England.

This extreme weather has already scorched mainland Europe. Tinder-box forests and strong winds have fed furious wildfires in France, Spain and Portugal. In the Portuguese town of Lousa, mercury soared to 46.3C, an all-time high.

Hotter than Ouargla in the Sahara Desert. Almost as hot as today's weather at Furnace CreekThe hottest recorded temperature, but probably not the hottest place on Earth. Satellite readings suggest the Lut Desert in Iran can reach a blistering 70.7C., Death Valley - which hit 56.7C in the summer of 1913. A world record.

It is not "a chance to play in the sun", warns UK Met Office chief Penny Endersby. In 2003, a catastrophic heatwave killed 70,000 people across Europe. Contingency plansPreparation for a possible event. Plans include rail speed restrictions, protection for people stuck in traffic, and more emergency hospital staff on duty. have been prepared by Cobra - the emergency committee that deals with storms, floods and terrorist attacks.

The Met Office advises people to change their "working practices and daily routines" to avoid heat stressWhen the body fails to cool down. It causes heat rash, exhaustion, muscle cramps, confusion and eventually a loss of consciousness.. Is it time to change the law?

Thirty-seven MPs have signed a motion to set a legal limit of 30C in all workplaces. They argue extreme temperatures cause: "dizziness, tiredness, asthma, throat infections, heat stroke and death". The Unite union supports the move, saying employers have a "legal and moral duty" to protect workers' health.

The same applies to schools. Teacher Nick Jones says it is "incredibly difficult" to sit exams in this heat. Teachers' unions want better ventilation and air conditioning in schools.

Government guidanceWorkers are protected by the Health and Safety at Work Act 1974 and employers are regulated by the Health and Safety Executive. says employers should keep temperatures "reasonable" and supply "clean and fresh air". But one size does not fit all, say supporters of the status quoA Latin phrase referring to the current or present situation.. Kitchen staff, steelworkers and factory engineers all put up with heat of 30C or more as part of the job.

If we all down tools in a hot spell, the nation would shudder to a halt.

This heat is "absolutely unprecedented", says the Met Office chief. The OED definition of a heatwave is "​a period of unusually hot weather". Climate scientists warn UK temperatures could top 40C every three to four years by 2100.

Europeans may have to get used to sweating it out. Other countries already set limits to protect health. China bans all outdoor work over 40C and the United Arab Emirates restricts work during the hottest hours of the day.

Yes: Of course, this is basic common sense. Above and below normal temperatures, people cannot do their job correctly and may become seriously ill. Governments should step in and keep workers safe.

No: The world is not that simple. Everyone has their ideal temperature and some jobs are by definition hot. As our climate heats up, we will have to learn to live and work at higher temperatures.

Or... Some of the hottest jobs are also the lowest paid. So instead of limiting working temperatures, we should offer higher wages for those who have to do sweltering work.