This weekend’s Austrian Grand Prix has been declared a heat-hazard race by Formula 1’s governing body the FIA.

The designation comes at any event where the temperature is forecast to exceed 31C at any time the cars are on track.

The ruling means drivers can use a mandated cooling kit that flows cooled liquid, such as glycol, through a system of pipes in a fireproof top worn under their overalls.

The cooling kit is not mandatory but any driver who chooses not to use it has to carry 5kg of ballast in their car to ensure he does not have a competitive advantage.

Austria is the first race this year to be declared a heat hazard, amid a heatwave across Europe that is establishing record temperatures in many countries, including the UK.

The rule was first introduced last year, when the Singapore and US Grands Prix ran under the designation.

Some drivers prefer not to use the cooling kit because of discomfort, and because there have been issues with the coolant running out before a grand prix is finished, in which case the liquid ends up at car temperature, which is considerably higher than ambient.

Temperatures in the cockpit of an F1 car can be more than 40C, and drivers are wearing several layers of fireproof clothing in addition to a balaclava and helmet, so overheating is a serious concern.