Air pollution levels for people living near a busy road are as bad for the lungs as smoking 20 cigarettes a day, according to a new study.
It fuels deadly emphysema, a type of chronic obstructive pulmonary disease (COPD) that causes breathing difficulties.
Living on a busy road for a decade was found to be equivalent to getting through a packet of cigarettes daily for 29 years.
Senior co-author Professor Joel Kaufman, of the University of Washington, said: ‘We were surprised to see how strong air pollution’s impact was on the progression of emphysema on lung scans, in the same league as the effects of cigarette smoking, which is by far the best-known cause of emphysema.’
Previous research has shown a clear link between air pollution and heart and lung diseases.
But the latest study, published in the Journal of the American Medical Association and involving 7,071 adults aged 45 to 84 living in six US city areas, is the first to show an association with emphysema.
There is a particular problem with ozone, a toxic greenhouse gas formed when pollutants emitted by cars and factories chemically react in the presence of sunlight.
Increasing rates of the potentially fatal lung disease were seen on lung scans of participants.
Emphysema is a condition in which destruction of lung tissue leads to wheezing, coughing and shortness of breath, and increases the risk of death.
Air pollution – especially ozone – accelerates the progression of the illness, say the US team.
A rise of three parts per billion in ozone levels compared to another location over 10 years meant an increase in emphysema.
The increased risk was the same smoking a pack of cigarettes a day for almost three decades, said the researchers.
And the study found ozone levels in some major US cities are increasing by that amount, due in part to climate change.
Dr Kaufman said: ‘Rates of chronic lung disease in this country are going up and increasingly it is recognised that this disease occurs in non-smokers.
‘We really need to understand what’s causing chronic lung disease, and it appears that air pollution exposures that are common and hard to avoid might be a major contributor.’
Earlier this year a study found air pollution kills nearly nine million people across the world each year – twice as many as global health chiefs had assumed.
German researchers said breathing in toxic air caused by vehicle exhaust fumes, factories and power plants is responsible for more deaths than smoking.
The World Health Organisation (WHO) previously estimated air pollution was to blame for 4.5 million deaths across the world.