As the train pulled into Oxford Circus, I made a split-second decision that haunts me to this day and kept it on. Big mistake. Huge. Without painting too graphic a picture, I bought a new mask at lunchtime.
But other than mercifully rare exceptions such as this, I cannot conceive of a reason why those without medical exemptions are incapable of wearing wear a mask on the Tube.
This week, Sadiq Khan called on the “selfish minority” of Londoners who refuse to wear face coverings on TfL services - a condition or travel - to do so. “Minority” might be a little generous - I’d say no more than half of people on my commute wear a mask, but I support the sentiment.
The Mayor then went on to suggest that hundreds of TfL enforcement officers across the network are just waiting to ask non-compliant passengers to leave transport services, a threat that might carry more weight if stations still seemed to have staff.
Politicians of all stripes like to pretend that the British public are the real heroes of the pandemic. This flattery suits their purposes - in a democratic system, it rarely pays to blame the electorate, as much as successive Labour leaders have tried.
But the wearing of face masks - or lack thereof - is an example of where the politicians really ought to dissolve the people and elect another. Some things in life require real sacrifice, others mere mild discomfort. Wearing a mask on the Tube barely even qualifies as the latter.
Of course face coverings - particularly of the flimsy, loose-fitting variety that cannot conceivably block minuscule aerosol particles - are unlikely to protect us from Covid alone.
But they help form one more layer of the so-called Swiss cheese model of pandemic defence, whereby the cumulative impact of imperfect responses - from social distancing to ventilation and vaccines - help to form a solid protection against transmission.
There are so many things individual citizens cannot control, from the speed of vaccine production to the temperature on the Central Line. But we can all wear a damn mask.