Researchers found residents who lived in a city centre were almost twice as likely to suffer from calcium build up in their arteries than those living in rural areas.
The condition predicts the development of heart disease – the higher the calcium score the greater the risk of having a cardiac event such as a heart attack.
A team from Svendborg Hospital in Denmark spoke to 1,225 men and women aged 50 and 60 years of age, including a fifth who lived in the centres of major Danish cities.
Despite the fact that none of the participants showed any symptoms of heart disease, 43 per cent of the total had coronary artery calcium (CAC).
The study found that people who lived in city centres were 80 per cent more likely to develop CAC than those living in other areas with men particularly at risk.
Smokers, age and diabetes were other common risk factors.
Lead author Dr Jess Lambrechtsen said: ‘Our study shows that living in a city centre and traditional risk factors for heart disease were independently associated with the presence of CAC in a group of middle-aged subjects who did not display any symptoms’ concludes Dr Lambrechtsen.
Participants were selected at random from a national Government database of Danish adults and 69 per cent agreed to take part and attend one of four regional hospitals in Southern Denmark.
They filled out questionnaires about their medical conditions, prescribed medication, smoking habits and family history of heart disease. The clinical examination included height, weight, blood pressure, blood tests and scans.
Three per cent were excluded from the study because of previous heart problems, leaving 1,225 people who did not display any symptoms of heart disease. One in five were city centre dwellers.
Air pollution levels were extracted from a national surveillance source. This showed that rates were approximately three times higher in city centres than other urban areas and seven times higher than in rural areas.
Dr Lambrechtsen said: ‘A number of factors can also influence CAC, such as noise and stress levels and it could be assumed these would be higher in city centres.
‘However, in this study stress levels, as measured by average blood pressure, were actually lower in city centre dwellers than people living in urban areas. Heart rates, another predictor of stress, were the same across the groups.
‘The mechanisms by which air pollution may contribute to CAC are not well understood. But what is clear from this study is that the links between air pollution and CAC need further investigation.’
The study was published in the May issue of the Journal of Internal Medicine.