The capital and other towns, some with populations as small as 30,000, were forced to apply speed restrictions and advise motorists to take public transport where possible. The city of Nice, on the Cote d'Azur, was accused by environmental activists of ignoring its legal duty to warn the public of air pollution at the weekend for fear of driving away tourists.
The city authorities and local officials of the national government denied the charges, claiming that the official figures had reached them too late. Pollution alerts of category two - serious danger to health - were belatedly in force in Nice, Cannes and Antibes yesterday. Similar alerts, and restrictions on cars, were triggered in cities from Bordeaux to Strasbourg and Le Havre to Grenoble. Even tougher restrictions, banning certain cars, were in place in Toulouse in the south-west and Thionville and Colmar in the north-east.
In almost all cases, the pollution recorded was an excessively high level of ozone - more than 180 microgrammes for every cubic metre of air - caused by a noxious mixture of car fumes and hot air. After weeks of cold weather, a windless heat wave settled two days ago.
Under a law passed in 1996 local authorities must warn the public, impose speed restrictions and encourage drivers to switch to public transport when the presence of ozone or other pollutants reaches level two. When the level one threshold is breached, some cars are banned (in Paris cars with odd and even numbers on successive days). The level one alert has been breached in three cities.
n Florence has become the latest Italian city to crack down on tourists who lounge, picnic or nap at historic sites. As of yesterday, visitors can no longer sprawl or eat on the steps of Palazzo Vecchio in Florence that dominates Piazza della Signoria. Venice earlier banned picnics in St Mark's Square.