A smoking ban comes into force in the Brazilian state of São Paulo on Friday, adding to what has become one of the world’s toughest anti-smoking campaigns.

Brazil was among the first countries in the world to print disturbing images on cigarette packs in an effort to persuade smokers not to light up. The images, in use since 2001, have coincided with a steady fall in the number of smokers in the country, from 34 per cent of the adult population in 1989 to 15 per cent last year, although the part played by the images is hard to gauge.