A study from the British Lung Foundation (BLF) estimated 700,000 more people than previously thought may be at risk of the disease.
A survey of 1,000 people in the UK asked patients whether they suffered from symptoms of the condition, including breathlessness, a regular cough, phlegm and wheeze.
The results suggested 22.8 per cent of respondents were at medium risk and 7.4 per cent were at high risk.
Dame Helena Shovelton, chief executive of the BLF said early diagnosis was essential to slow progression of the condition and ensure patients do not 'suffer in silence'.
She said: 'This is why the BLF is encouraging those with symptoms to take the BLF's online breath test or to visit their GP.'