Air pollution is shortening life expectancy in Europe, causing asthma among children and chronic bronchitis and heart disease among over-65s. It is also costing a fortune. However, according to Europe's Aphekom programme, there is a big difference in health between the residents of dirty Bucharest and those in clean Stockholm. The study lasted three years in 12 countries and 25 cities, home to 39 million people.

"The figures show that, despite the various countermeasures, air pollution is still a major issue for public health in Europe," said Sylvia Medina, who is a study co-ordinator and an epidemiologist.

The researchers calculated the potential gain in life expectancy if fine-particle pollution was reduced to 10 micrograms per cubic metre as an annual average, which is the target set by the World Health Organisation. Fine particles go deep into our bodies, affecting our heart and lungs.

The high concentration of many fine particles, largely due to emissions from diesel engines and heating systems, knocks almost two years off the average life expectancy of residents of Bucharest, and six months off the life of Parisians. Pollution in Stockholm is already below WHO targets.

The study then focused on 10 cities including Barcelona, Brussels and Rome, and, for the first time, took account of the extent to which pollution may trigger chronic complaints rather than just exacerbate them. About half the urban population lives close to a road with more than 10,000 vehicles a day, and that fact seems to be responsible for 15% of asthma cases among under-17s, 23% of chronic bronchitis cases, and 25% of cardiovascular diseases among over-65s.

Traffic over 10,000 vehicles a day is "fairly commonplace in large towns", says Karine Léger, an engineer at Airparif, the organisation that is tasked with monitoring air quality in the Paris area. The average on the Paris ring-road, the Boulevard Périphérique, is 270,000 vehicles a day, and 20,000 amid the boutiques of Rue de Rivoli.

The annual cost, including time spent in hospital and lost working hours, of fine-particle pollution for the 25 cities covered by the study is estimated at $43bn. "It is a high cost, impacting directly on the health service," says Olivier Chanel at France's National Research Centre. "The benefit from reducing average levels of exposure would be far from negligible." Progress has been made for some substances such as sulphur dioxide, but fine-particle pollution is not improving.

Yielding to pressure from new members of the European Union, Brussels has set a very high threshold for 2012. Following an assessment in 2013, this may be lowered in 2020. In France plans to enforce a 15 micrograms per cubic metre threshold have been replaced by a 20 micrograms per cubic metre target, combined with a discretionary 10 microgram "quality objective". The threshold in the US is 15 micrograms, and 10 micrograms in Australia.

Several French cities – Bordeaux, Lyon, Grenoble, Nice, Clermont-Ferrand, Aix-en-Provence and Plaine Commune, in the Paris suburbs – have volunteered to take part in an environment ministry experiment. Starting in 2012, heavy-polluting vehicles will be banned from their central areas.

After a noisy parliamentary debate an article was included in legislation allowing conurbations with more than 300,000 inhabitants to impose congestion charges. Cities such as Stockholm and London, where pollution is under control, have already introduced such measures.

The study does not only concern local and national government, as Medina pointed out. Everyone could restrict their exposure to pollution by avoiding stationary cars with their engines running, keeping windows closed during the rush hour, walking down streets with less traffic and making "more rational use" of transport.

This article was first published in Le Monde