Mask wearing on public transport looks likely to be with us for some time.
But the most recent figures from Transport for London (TfL) show there is still a significant minority that do not wear them.
Commuters have also complained to me about maskless rail staff who also ignore social distance regulations.
TfL said about 90% of its passengers wear masks.
Around 137,000 maskless people have so far been stopped from using London's public transport and told to wear a face covering since it was made mandatory on 15 June, latest figures show.
Most passengers do put on their masks when asked to do so by enforcement officers, TfL said.
However, around 9,800 people were prevented from boarding and a further 2,100 people were removed from services for not wearing a mask.
Those 2,100 people were then issued £200 Fixed Penalty Notices by TfL officers.
Of course, enforcement officers do have to check with every passenger if they are exempt from wearing a mask.
If a passenger says they have an exemption, staff must take their word for it, TfL said.
I put that to Siwan Hayward from TfL.
"That's the way the law is constructed. Some of my colleagues are frustrated that there's not a requirement to prove you're exempt," she said.
"However, my officers in TfL are all very well trained at getting honest answers out of people and will be able to make a judgement.
"We're pretty confident the system is working pretty well," she said.
Commuters have also complained that some rail staff do not wear masks when dealing with customers.
While there is no legal requirement for it, operators I spoke with said staff are told to wear a mask to "set an example to passengers" - unless, of course, they have a medical exemption.
One operator said: "We urge customers to let us know of specific instances where these standards are not being met so we can follow up robustly."