Smoking
Smoking (including exposure to second-hand smoke) is the leading cause of COPD. About 50% of smokers will eventually develop this condition in their lifetime, and roughly 75% of COPD cases occur in people who smoke.

Why is smoking harmful?

The answer lies in the over 7,000 substances released when a cigarette burns, many of which are dangerous. Specifically, these harmful substances:

• Weaken the respiratory system’s natural defences against infections.
• Reduce airflow, making it harder to breathe.
• Cause changes in lung tissue, particularly damaging the alveoli (the small sacs where oxygen and carbon dioxide are exchanged between the air and blood).

Air pollution
Long-term exposure to particulate matter (such as PM 2.5 and nitrogen dioxide) can increase the risk of developing COPD.

Where Does PM 2.5 Come From?
PM 2.5 is found in smoke produced by:

• Agriculture and livestock farming
• Motor vehicles
• Factories
• Power plants
• Burning wood

Exposure to poor air quality significantly raises your risk of COPD.
Be mindful, indoor air pollution can also pose a risk (such when cooking in poorly ventilated spaces).

Occupational pollution
Between 10% and 20% of people who are exposed to certain substances at work may develop lung issues associated with COPD. Common exposures include:

• Chemicals
• Fumes
• Burning wood
• Fertilizers
• Pesticides
• Organic and inorganic dust

Occupations at higher risk include farmers, sculptors, artisans, and those working with plastics or specific chemicals.

Genetic predisposition
Certain genetic factors can increase the risk of developing COPD.
Specifically, a deficiency in the alpha-1 antitrypsin protein – a protective molecule produced by the liver – is linked to lung conditions like COPD.

Lung and bronchial infections
Mycobacterial infections, as well as chronic infections caused by Pseudomonas aeruginosa and other bacteria, can increase the risk of developing COPD.