Thinking about it in virus terms, I'd have thought that sitting in a field must be lower risk than walking down a busy street and a lot safer than shopping in a busy, air-conditioned supermarket. Showers and toilets might be considered higher risk but again, you're unlikely to be closer than several metres to anyone – I never saw anyone there when I was at Twitey's last year – and the risk from contacting surfaces is, again, lower than in a supermarket (fewer people, easier to keep the surfaces clean, nothing frozen, nothing to be consumed). That just leaves train, if you take one to get there.