The new rules will come into effect from January 1st 2021 after a majority of local councillors voted in favour of the ban on smoking outdoors in places such as public transport stops, parks, chldrens' play areas, sports stadiums and cemeteries.
Smoking will be banned within 10 metres of other people, reports Italian news agency Ansa.
The clean air legislation also includes a requirement for petrol stations to install electric car-charging points, and the phasing out of diesel-powered heating systems.
Milan mayor Giuseppe (Beppe) Sala is planning to ban smoking completely in all public outdoor areas from January 1st, 2025, prompted by studies showing how smoking contributes to pollution, Italian newspaper La Stampa writes.
Along with other cities including Rome and Florence, Milan was recording dangerously high pollution levels – specifically of PM10 fine particles – at the beginning of the year.
Some vehicles were banned from driving in city centres during what officials called the “smog emergency”.
While pollution levels lowered dramatically during Italy's coronavirus lockdown, public awareness was focused on Italy's long-standing issues with pollution when the preliminary results of studies suggested a possible link between poor air quality and illness due to Covid-19.
Italy has had a ban on smoking indoors since 2005, but rules are less strict than in some other European countries; smoking is allowed on bar and restaurant terraces and next to the doors of public buildings, for example.
Some Italian cities have stricter local measures in place. In Verona and Bolzano smoking is banned in parks and green spaces.
Venice's mayor also proposed banning smoking in the city centre last year, though nothing has come of it yet.
Milan is so far unique among Italian cities in approving a ban on smoking outdoors in public.