Twenty years of smoking cessation may restore some lung function as well as improvement in airway mucosal inflammation, but damage to the lung parenchyma cannot be restored, and the decline in lung function may be delayed.
If the smoking age has reached twenty years, some lung function may be restored after quitting smoking. Meanwhile, due to long-term smoking, airway mucosal inflammation can be improved after quitting smoking, then cough and other symptoms can be recovered to a certain extent.
However, the damage to the lung parenchyma, such as tracheobronchial mucosal damage and pulmonary pustules, is irreversible. At the same time, it is necessary to continue to quit smoking and not to return to smoking. However, smoking cessation has a delaying effect on the decline of lung function.
However, smoking cessation is helpful for the recovery of this type of injury, and smokers are encouraged to quit smoking as soon as possible.