From Matthew Parris's Times diary:

https://www.thetimes.co.uk/article/camerons-old-rival-has-given-his-shins-a-kick-xvv5vh6d3?shareToken=c7534baefb95653d9a76e23bcd074 109

Black mark on Covid

Expert opinion is now clear that it’s very rare to contract Covid-19 from
surfaces. But still the trilogy “hands, face, space� is intoned:
sacrosanct, a medical mantra. Government communications should understand
that if changed assessments of risk are passed on only when the risk is
being upped, and never when lowered, we do notice. A ratchet operates. This
irritates, undermining faith in all official warnings.

So on the London Tube I’ve resumed holding the handrails when climbing or
descending stairs and escalators. And guess what? You now get a thick black
line across your palm, when you never used to. I have a theory. Falling on
to handrails is an invisible rain of iron filings from carriage brakes,
wheels and rails. Normally, so many passengers’ hands continuously wipe
these handrails that no hand shows the mark. But when it’s only you, you
collect the lot. Then you touch your trousers, and all is lost. Someone
should examine the lungs of the mice that live between the rails.