If there's one issue that angers commuters, it is other travellers not wearing face coverings.
The new law was introduced on 15 June and for the last month it has been mandatory to wear face coverings on public transport.
So is it working?
The authorities say 90% of people abide by it but there is plenty of anecdotal evidence that some are still not wearing a face covering and there are many examples of people not wearing the coverings correctly.
Transport for London (TfL) says compliance is higher on the Tube and in rush hour.
The authorities had spoken about social pressure playing a part in getting people to wear a mask, in the same way the alcohol ban on transport worked.
Now though it seems TfL and British Transport Police (BTP) are ramping up their enforcement.
In the first month, BTP across the UK, asked about 18,500 people to wear a covering and asked more than 800 to leave the network. TfL has warned more than 10,000 passengers.
In total BTP and TfL have issued 59 fines.
The enforcement officers we went filming with had to check with those not wearing a mask to see if they had an exemption first.
There are exemptions for children, for people with certain health problems and also if wearing a face covering would cause you "severe distress".
The law also says you can remove the covering for eating and drinking.
Transport employees are also exempt although all customer-facing TfL staff have to wear them - excluding bus drivers where it is a personal decision as they work within the sealed off cab.
The enforcement staff will not be able to cover the whole network and so social pressure will still play a large part in the new normal. The commuters we spoke to certainly thought everyone should be wearing one.
Heidi Alexander, deputy mayor for transport, told me: "We have really been quite pleased with compliance particularly on the Tube, particularly in rush hour, but this needs to apply 24/7.
"So whether on a bus or a Tube or a train, you should be wearing a face covering.
"We will continue to do all that we can to make sure people do understand that. That includes issuing fines, (and) refusing entry if necessary if they don't have a face covering, because it really is important to protect everyone."