One of the main causes of COPD is prolonged exposure tocigarette smoke, especially if the smoke is inhaled. Butbreathing in secondhand smoke, air pollution, chemical fumes or dust from the workplace also can cause thecondition².

These inhaled particles can cause the mucus glands thatline the bronchi to produce more mucus than normal. Inaddition, the inflammation that they trigger causes thewalls of the bronchi to thicken and swell. Environmentalfactors and genetics may also play a part in thedevelopment of COPD ²∙⁵.