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At first glance, taking public transportation seems like a particularly risky activity in the face of the coronavirus pandemic, but in several major cities where ridership has rebounded, there haven't been any outbreaks linked to subways, buses, or commuter railways, The New York Times reports.

In Paris, contact tracers have not found public transportation to be linked to any of the city's 386 coronavirus clusters between early May and mid-July. The same goes for Tokyo's famously busy system, and an Austrian study also did not tie any outbreaks to public transportation in the country.

The findings are encouraging, but come with some caveats: Ridership still falls short of pre-pandemic levels in most places, and those cities where passengers are taking public transportation in more significant numbers have mandated masks, disinfected trains and buses, and ramped up service to avoid overcrowding. Of course, that will likely be the blueprint for many cities going forward, at least while the pandemic continues.

The trickier aspect might have to do with contact tracing. Experts warn that it's challenging to trace an outbreak to public transportation because there's little chance people will remember their precise train car, and it's even more difficult to track down who else was in the same space.

A lot remains unknown, but the Times reports that riding public transportation probably falls somewhere in between walking outdoors and dining indoors on the safety scale. Read more at The New York Times. Tim O'Donnell