Haha, he has put on a bit of weight - does that make a difference then? He's not huge, probably not even classed as "overweight", just... "more solid" than he used to be
Temp. is same as it's always been I think, and no asthma or anything :shrug:
And it's a second floor flat, if that helps.
The age of the building, and possible minor mold spores in the air, are the greatest concern when someone suddenly starts snoring. If the house you are in never had any problems with that and was built after ~1980 (Is that Peterborough, County Cambridgeshire, or Peterborough, Ontario?) it shouldn't be a problem in most countries.
If he indeed put on a little weight, it might have gone to the back of the throat, too, and that's one of the most common causes of snoring. It's a genetic thing where weight goes first, so it doesn't need real overweight to lead to possible breathing problems in certain positions.
There are some insanely costly tools to train the jaw and neck muscles to help with this, but learning to and then playing the Didgeridoo does the same.
Other than that, weight reduction should help. ^_^