<unk> , or pulmonary<unk> , is a lower respiratory tract disease, characterised by air-filled spaces (pneumatoses) in the lung, that can vary in size and may be very large. The spaces are caused by the breakdown of the walls of the alveoli and they replace the spongy lung parenchyma. This reduces the total alveolar surface available for gas exchange leading to a reduction in oxygen supply for the blood.<unk>  usually affects the middle aged or older population because it takes time to develop with the effects of smoking, and other risk factors. Alpha-1 antitrypsin deficiency is a genetic risk factor that may lead to the condition presenting earlier. When associated with significant airflow limitation,<unk>  is a major subtype of chronic obstructive pulmonary disease (COPD), a progressive lung disease characterized by long-term breathing problems and poor airflow. Without COPD, the finding of<unk>  on a CT lung scan still confers a higher mortality risk in tobacco smokers. In 2016 in the United States there were 6,977 deaths from<unk>  – 2.2 per 100,000 of the population. Globally it accounts for 5% of all deaths. A study on the effects of tobacco and cannabis smoking showed that a possibly cumulative toxic effect could be a risk factor for developing<unk> , and spontaneous pneumothorax. There are four types of<unk> , three of which are related to the anatomy of the lobules of the lung – centrilobular or centriacinar, panlobular or panacinar, and paraseptal or distal acinar<unk> , and are not associated with fibrosis (scarring). The fourth type is known as paracicatricial<unk>  or irregular<unk>  that involves the acinus irregularly and is associated with fibrosis. Though the different types can be seen on imaging they are not well-defined clinically. There are also a number of associated conditions including bullous<unk> , focal<unk> , and Ritalin lung. Only the first two types of<unk>  – centrilobular, and panlobular are associated with significant airflow obstruction, with that of centrilobular<unk>  around 20 times more common than panlobular. Centrilobular<unk>  is the only type associated with smoking. Osteoporosis is often a comorbidity of<unk> . The use of systemic corticosteroids for treating exacerbations is a significant risk factor for osteoporosis, and their repeated use is recommended against.
Emphysema
Pleurisy
Plastic bronchitis
Atelectasis
Empyema
Reactive airway disease
Bronchiectasis
Acute bronchitis