Why am i having a crackling sound in lungs when exhaling?

Bronchitis?: One explanation for crackling and wheezing sounds on exhalation is inflammation / infection of the breathing tubes (bronchi). This is called bronchitis. Pneumonia and partial occlusion of bronchi (by mucus or a foreign body) are other things that can cause expiratory crackling. Some people with 'fluid in the lungs' or pulmonary edema may also have expiratory crackling sounds.