It's not just China that's looking for novel ways to cut down on air pollution. Facing health warnings over dangerously high levels of particulates across much of France, authorities in Paris say levels have reached levels much higher than those deemed safe by the World Health Organization — the worst in a decade — and the city is once again taking extraordinary measures to bring emissions under control.

All buses, subways, trains and the city's bike-share program are free of charge, some for the second day, reports The Christian Science Monitor. Even the city's famous Autolib' electric car-share program will offer a first hour free with the purchase of a subscription. The measures come alongside other initiatives such as reduced speed limits — which police are taking extra measures to enforce — as well as municipal vehicles being taken off the roads unless their use is absolutely necessary. The odd/even approach to license plate numbers limits the number of cars that can be in the city center on any given day.

The moves also continue a push by Mayor Anne Hidalgo last year to remove all diesel cars from the streets.

An unplanned PSA for public transit

The free transit, however, offers the promise of more than just temporary respite from smog. Even though transit ridership is increasing in many parts of the world, including in the U.S., transit advocates often say that getting people to try public transit is often the biggest challenge; once they do they often find it easier, more convenient and pleasant than they had imagined.

It's a shame, of course, that it takes dangerous levels of pollution to spur such measures in the first place. Perhaps a case could be made for making all transit free, or at least offering free rides on certain days to get people hooked.

This story was originally published in March 2014 and has been updated with more recent information.