According to health experts, 80% of people suffering from severe chronic lung disease associated with smoking in UK are not even aware of it.
Chronic Bronchitis and Emphysema constitute the condition, Chronic Obstructive Pulmonary Disease (COPD). Long-term damage to lung tissue by smoking can lead to the development of lung cancer as well as COPD.
Professor Robert West, director of tobacco studies at Cancer Research UK's Health Behavioural Unit and his team conducted the study on 8,215 adults. The findings were published online by the journal Thorax. The saliva and lung function test results were examined by the researchers.
On the basis of damaged lung function, 1,093 people were identified to have COPD. However, over 80% said there they were not aware of it. Over 50% of those with severe COPD had also not been diagnosed. Over 1/3rd of them were still smoking while 35% of them were ex-smokers.
Usually, old men, laborers and poor people are the ones being affected by this disease.
Dependence on cigarettes and the number of cigarettes smoked were higher among smokers with the disease than smokers not affected by it, according to the study. However, smokers with COPD had no intention of quitting smoking.
Lead researcher Professor Robert West, 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 think the symptoms of COPD - such as a smokers' cough or becoming breathless during exercise - are 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, appreciated the research, and said the charity would be launching a campaign in October to raise awareness of COPD.
COPD takes lives of over 30,000 every year and is the sixth major cause of death in England and Wales. 600,000 - 900,000 Britons have been diagnosed with COPD.