When a smog alert is declared in the Czech capital Prague in the future, public transport will be free.

The scheme to combat bad air quality will allow anyone - including tourists - to benefit from the free rides, according to a spokesman for the city administration.

Given that Prague experiences between five and seven days of smog alarms each year - mostly due to vehicle pollution - the move is expected to cost around 200,000 euros (227,000 dollars) annually.

The city at the same time is launching an information campaign encouraging carsharing, and is planning to increase penalties for drivers who deliberately remove their car's particle filter to save on petrol.