I havent been able to read the article, I tried on 3 different browsers but the headlines say it all.
Personally I think it is an urban myth as anesthetists have said that
1. the volume of gas required to apply a knock out to the occupants is to large without someone seeing it being done
2. without knowing the body mass of the occupants should they actually have the volume required they would more than likely kill them
also the gas required is expensive and why spend hundreds of euros in the likelyhood of stealing an old camera and a second hand laptop.
There has been a bit in the media about Jenson Button the racing driver being gassed at his holiday home in St Tropez but again it was the media who said it was gas, not the police or Jenson.
I think a lot of people who have been supposedly gassed were in a deep alcohol induced sleep, forgot to lock the doors/windows correctly and need a reason to explain their negligence. Burglars can and will get into most properties including motorhomes without disturbing the occupants and its usually the opportunist theives who will disturb everyone.
My advice is go enjoy your holiday and just apply common sense about your belongings when leaving the van, gas masks are not required, unless you have eaten a load of beans
