Slashing air pollution in urban areas to levels found in the countryside could add years to the lives of city dwellers, a new study found.
It would give men between one and two years extra and women six months to a year in Copenhagen, a population of over 616,000 people similar in size to Bristol or Belfast.
And they will have less illnesses such as cardiovascular disease and asthma.
But if air pollution was reduced by a fifth the result is an increased average lifespan of between three to six months.
Diesel engines pump out nitrogen dioxide or NO2, along with minute soot particles.
Previous studies have linked this particle pollution to an increased risk of diseases like lung cancer, respiratory diseases and cardiovascular diseases.
So University of Copenhagen scientists looked at levels of NO2 as an indicator of local smog.
And it found if air quality in the capital was similar to the countryside by 2040, they would have a longer lifespan.
Associate Professor Henrik Brønnum-Hansen from the Department of Public Health said: ”
‘An important point of the new study is that you do not just get one more year to live, you also get more years without disease.
“So it is not just a question of the average lifespan, but also of quality of life.
“Of course this reveals to the decision-makers the potential if they were to really do something about the air pollution.
“Copenhageners can live longer lives, because fewer would get sick and die from diseases which we know are caused by air pollution, among other things”
The study used advanced models named ‘DYNAMO-HIA’ to simulate the effect of air pollution on the population.
It used data from large population surveys on health, pollution calculations for the individual streets based on traffic patterns and register data regarding address, contact with the hospitals and mortality.
The traditional method for evaluating health effects underestimates the effect of traffic so researchers painted a much more precise picture by looking at NO2, which is closely connected to all health effects in Danish surveys, even though some of the effects are caused by particles.
The level of pollution in Copenhagen is approximately three times as high as the level measured at a measuring station just outside the city of Roskilde.
The annual mean NO2 concentration was 19.6 μg/m3 and for 70 per cent of the population the range of exposure was between 15 and 21 μg/m3.
If NO2 exposure was reduced to the annual mean rural level of 6 μg/m3, life expectancy in 2040 would increase by one year.
In addition to living longer, residents will be more disease free.
The greatest gain in disease-free life expectancy would be lifetime without ischemic heart disease (1.4 years), chronic obstructive pulmonary disease (1.5 years for men and 1.6 years for women), and asthma (1.3 years for men and 1.5 years for women).
Co-author Professor Steffen Loft said: “Of course our scenario is ambitious, because it more or less requires all polluting vehicles to be removed from Copenhagen.
“But if you want to prevent a large number of cases of disease and increase the average lifespan by an entire year, you need to do something drastic – and 2040 is way into the future, so it is not unrealistic.”
Prof Brønnum-Hansen added: “The conclusion of the study was that lowering the NO2 exposure by reducing traffic-related air pollution would reduce incidence and prevalence of major chronic cardiovascular, respiratory and metabolic diseases and lung cancer, and increase disease-free life expectancy.
“The full potential of health gain by reducing NO2 exposure level to that of rural areas would increase life expectancy in Copenhagen between one and two years for men and between a half year and one year for women.
“These results combined with previously recognised negative health effects of noise from road traffic are relevant to take account of in planning of future urban traffic.”
The study was published in the journal Environment International.