If you quit smoking, you may start to see improvement in your shortness of breath by 6 months. It may take longer for some people. Quitting smoking can prevent your shortness of breath from getting worse.

COPD makes it difficult to empty your lungs of air when you exhale. Air gets trapped in the lungs so there is less space to bring in new air and oxygen.

Quitting smoking can improve shortness of breath. Practicing deep breathing can also help. Deep breathing helps to strengthen the muscles that control breathing. Breathing out through pursed lips helps you to exhale more fully and push out more air from your lungs.

Source: www.healthline.com/health/copd/does-copd-progress-after-quitting-smoking