How to get cleaner air? Germany considers free mass transit

FILE - In this Nov. 24, 2017 file photo a short subway train carries commuters and pupils in the outskirts of Frankfurt, Germany. German ministers have discussed considering offering free public transportation to get more people to use environmentally friendly mass transit, but their idea has run into opposition by some German cities and towns, who think the plan is too expensive. (AP Photo/Michael Probst, file)

BERLIN — How best to get cleaner air? Some officials in Germany want residents to leave their polluting cars at home.