The single most important thing that can be done for someone with respiratory disease is to support them to quit smoking. Smoking is the biggest risk factor for the development and progression of COPD and is a trigger factor for asthma. 

The risk of developing COPD is directly related to the total number of pack years smoked, with anything over 15 pack years considered significant. Pack years are calculated as follows:

Number of cigarettes smoked per day x number of years the patient has smoked
20

Evidence shows that quitting smoking at any point in life will slow the progression of COPD. Therefore any patient, regardless of age, should be encouraged to stop smoking.