In an EU-funded study it was found that reducing air pollution in major European countries could save 19,000 lives per year, add life by two years and also save around 31.5 billion euros (43.4 billion dollars) in health costs.
The nearly three-year probe, called Aphekom, looked at 25 cities in 12 European Union (EU) countries, encompassing nearly 39 million inhabitants.
Only Stockholm was below the threshold of fine particulate pollution of 10 micrograms per cubic metre recommended by the UN's World Health Organisation (WHO), it found.
At the other end of the scale, Bucharest notched up 38.2 micrograms, Budapest 33.7 micrograms and Barcelona 27 micrograms per cubic metre.
Among other cities, pollution in Rome was 21.4 micrograms per cubic metre, while in Paris and London it was 16.4 and 13.1 micrograms per cubic metre respectively.
Fine particulates are tiny airborne grains that can be drawn deep into the lungs, with the potential to cause respiratory and cardiovascular disease.
The pollution comes from traffic exhausts, which means that it is particularly pronounced near major roads.
In a sub-set of 10 cities studied by Aphekom, scientists estimated that between 15 and 30 percent of cases of childhood asthma could attributed to living close to busy roads.