A question we're being asked quite a lot is whether the extra lengths we're going to in terms of hygiene to protect us from COVID-19 might cause us immune problems later because we're living lives that are too clean. This is the basis of what's dubbed the "hygiene hypothesis". But a report out this week says that, actually, it's the environment we've created - rather than the way we clean it - that matters, because modern living conditions and building materials select for the wrong sorts of microbes. Microbiologist and author of the report, Graham Rook, spoke to Chris Smith... Like this podcast? Please help us by supporting the Naked Scientists