Four out of five adults with long-term lung disease do not know they are ill, research suggests.
COPD can be life-threatening
The condition, Chronic Obstructive Pulmonary Disease (COPD), includes chronic bronchitis and emphysema.
It is strongly associated with lung cancer because both arise from long-term damage to lung tissue, which can be caused by smoking.
The study of 8,215 adults by the charity Cancer Research UK is published online by the journal Thorax.
Researchers studied the results of saliva and lung function tests.
It is estimated that 13.3% of Britons over 35 may have developed features
Between 600,000 and 900,000 people in the UK have been diagnosed with COPD
COPD is the sixth most common cause of death in England and Wales killing more than 30,000 a year
They identified 1,093 people with COPD based on impaired lung function, but more than 80% said they had not received diagnosis of any kind.
Even among those with severe COPD more than half had not been diagnosed.
More than one third of those with the condition were still smoking and a further 35% were ex-smokers.
Sufferers were more likely to be older, manual workers, male and more socio-economically deprived.
The study also found that smokers who had COPD showed higher levels of dependence on cigarettes and smoked more cigarettes a day than smokers without the disease.
But those with COPD were no more motivated to quit than smokers without the disease.
Lead researcher Professor Robert West, director of tobacco studies at Cancer Research UK's Health Behavioural Unit, said: "It is crucial to identify smokers with COPD and take urgent action to support them in stopping smoking because the most effective way of halting the progression of the disease is to stop smoking.
"Many smokers feel that they will 'get away with it' and not be affected in a serious way by their habit.
"For smokers with COPD that doubt is removed. Every day they continue to smoke will make things worse."
Professor West said many smokers thought the symptoms of COPD - such as a smokers' cough or becoming breathless during exercise - were normal.
"They do not realise that they can be the beginnings of a disease which, in many cases, will leave them disabled or dead if they do not stop smoking.
"It only requires a simple lung function test to find out whether they have COPD and this can be done by their GP."
Dr Lesley Walker, director of cancer information at Cancer Research UK, said: "Smokers run the biggest risk of COPD but we also know it can affect people who have never smoked as well as those who have given up smoking.
"There is a real need to increase public awareness of this insidious disease."
Dame Helena Shovelton, chief executive of the British Lung Foundation, welcomed the research, and said the charity would be launching a campaign in October to raise awareness of COPD.