The FIA has clarified its ban on non-regulatory underwear and body piercings ahead of this weekend's Miami Grand Prix, going a step further by making it part of official scrutineering.
Motorsport's governing body caused a stir earlier this season when it announced a clampdown on underwear that failed to comply with the rules, as well as making clear that all piercings were prohibited.
The latter edict prompted an issue with seven-time F1 champion Lewis Hamilton who made clear that certain piercings in his right ear were "welded in" and he would have to "get them chopped off or something like that, so they'll be staying".
Ahead of the race in Miami, FIA race director Niels Wittich has issued a note to the teams outlining the scrutineering declaration form for this race has been amended as it now includes checks relating to 'compliant underwear' and 'the wearing of jewellery'
Clarifying matters, the note states that "In case of justified medical reasons, non FIA-approved underwear may be worn between the driver’s skin and the compulsory FIA-approved underwear.
"However, the use of synthetic, non-flameproof materials in contact with the driver’s skin is not authorised.
"Drivers and co-drivers can wear additional flameproof underwear, which is not FIA approved, between their skin and the compulsory FIA-approved underwear.”
Wittich has taken the additional step of explaining why such underwear and its positioning is crucial.
The note added the new rule had been introduced "to ensure that the FIA-approved flame-resistant clothing, including both the outer layer overalls and inner layer in contact with the skin, can operate effectively and provide the designed level of protection if exposed to flames.
"The use of non-flameproof materials in contact with the driver’s skin, and in particular synthetic materials, can reduce heat transmission protection and thus increase the risk of burn injuries in the event of a fire.
"In the worst-case such materials may melt which can hinder treatment in the event
of a burn injury."
With regard to the prohibition of body piercings or metal neck chains, drivers may be subjected to checks before the start of the event.
The FIA claim that "the wearing of jewellery underneath the required flameproof clothing can reduce the protection afforded by this equipment".
The note added that: "Metallic objects, such as jewellery, in contact with the skin can reduce heat transmission protection and thus may increase the risk of burn injuries in the event of a fire.
"The wearing of jewellery during the competition can hinder both medical interventions as well as subsequent diagnosis and treatment should it be required following an accident.
"The presence of jewellery can slow, due to the risk of 'snagging', the emergency removal of driver safety equipment such as helmet, balaclava, and overalls.
"In the case that medical imaging is required to inform diagnosis following an accident the presence of jewellery on the body can cause significant complication and delay.
"In the worst case, the presence of jewellery during imaging may cause further injury.
"Jewellery in and/or around the airway can pose specific additional risks should it become dislodged during an accident and either ingested or inhaled."
It is yet to be determined what action will be taken should Hamilton or any other driver defy the new regulations.