If you're still unconvinced wearing a mask on public transport is necessary, new research into the source of an outbreak of COVID-19 in China might change your mind.
A single person who didn't even realise they were infected with the deadly virus managed to pass it onto 23 other people on a bus making a round trip to a religious event in China on January 19.
According to the report in journal JAMA Internal Medicine, the asymptomatic patient wasn't wearing a mask - at that stage, there had only been about 500 confirmed cases in the entire world. No one knew at that stage the virus could be passed from person-to-person - that wouldn't be confirmed until March. The virus' ability to infect people via airborne particles wasn't confirmed until much later.
The super-spreader who unwittingly brought the virus aboard the bus had been at a dinner two days earlier with a group of 10, four of whom had recently travelled to Hubei province, where the outbreak was first detected in late 2019.
There were 68 passengers on the bus, which made a 100-minute round trip, 50 minutes a time, to the Buddhist event in Ningbo. Of the 23 who got infected, they were seated all over - from the front to the back - with the blame being put on the bus' air conditioning system.
"The investigations suggest that in closed environments with air recirculation, SARS-CoV-2 is a highly transmissible pathogen," the researchers wrote, using the virus' scientific name.
"Our finding of potential airborne transmission has important public health significance."
Up until that point, Ningbo - about 700km east of Wuhan - had no reported cases of the virus. The index patient didn't start showing symptoms until the day after the event.
The present cluster of cases in Auckland is believed to have partly spread via public transport, hence the new nationwide requirement for all passengers and drivers to wear masks.
Masks work not just by preventing the wearer from inhaling potential virus-carrying particles, but stopping any particles they might breathe out from travelling far - which is why even basic masks made at home are considered fine if more expensive surgical-grade masks can't be sourced.
The findings come after a Wellington man bragged about not wearing a mask on a train on Monday.
"Know your rights but don't be an asshole," Joachim Wanihi wrote, prompting many on social media to call him an asshole.
Drivers aren't expected to enforce mask-wearing for their own safety, but police can issue $300 instant fines if they catch people not wearing one without a good reason.
