Rates of incurable lung disease are higher than previously thought, a study across 12 countries suggests.
Smoking is one of the major causes of COPD
Tests in almost 9,500 adults aged over 40 found one in 10 had chronic obstructive respiratory disease (COPD), which causes breathing difficulties.
Rates are set to rise further as the population ages, reported the US researchers in the Lancet study.
COPD is currently the fifth leading cause of death worldwide but is set to become the third leading cause by 2020.
COPD is an umbrella term for a range of conditions including chronic bronchitis and emphysema.
There are an estimated two million people in the UK who have COPD but have not been diagnosed.
Researchers from Oregon Health and Science University carried out spirometry tests to measure breathing in individuals from 12 countries.
They found 11.8% of men and 8.5% of women had moderate or higher stage COPD - more than has been reported in other studies.
There was also a strong link with age with the risk of the disease almost doubling with every 10 years over the age of 40.
Smoking is a major factor in developing the disease and explains much of the difference between rates in men and women.
But the researchers also found a fairly high prevalence of COPD in individuals who had never smoked, which they said raises questions about genetic susceptibility.
"This worldwide study showed higher levels and more advanced staging of spirometrically confirmed COPD than have typically been reported," said study leader Dr Sonia Buist.
Encouraging people to stop smoking was becoming increasingly important as people were living longer, she concluded.
But she said because of ageing populations "if every smoker in the world were to stop smoking today, the rates of COPD would probably continue to increase for the next 20 years".
A separate study in the same issue of the Lancet found that poor lung function shortly after birth is associated with poor lung function in early adulthood.
Better understanding of lung development in the womb may help to prevent COPD in later life, the researchers concluded.
Dame Helena Shovelton, chief executive of the British Lung Foundation said: "There are people with COPD who have never smoked and this research shows that deprivation, dust exposure and lung development in the womb play a vital role in causing the disease.
"The research also highlights how much more work is needed to improve our understanding of how environmental, socioeconomic and other factors can cause COPD."