tobacco

Tobacco is the leaf of the Nicotiana plant, cured and processed for smoking, chewing or inhaling. Its smoke is the single chief driver of respiratory disease worldwide — the common thread linking COPD, the bulk of lung cancers, and a long list of other illnesses. The plant itself is ordinary; what makes it so consequential is what its combustion releases and the addiction its nicotine sustains.

Nicotine, tobacco's principal active compound, acts on the brain to create a powerful dependence that keeps people using the product despite knowing its harms. But it is largely the products of burning tobacco — tar, oxidant gases, carbon monoxide and numerous carcinogens — rather than nicotine itself, that injure the lungs. Tobacco is consumed in many forms: cigarettes, cigars, pipes, water pipes (hookah) and heated tobacco; combusted forms are the most damaging to the lungs.

From a respiratory standpoint, tobacco is the dominant modifiable risk factor: eliminating it would prevent most COPD and a large share of lung cancer. This is why tobacco control — taxation, advertising bans, smoke-free laws, plain packaging and cessation support — is among the highest-impact public-health measures, and why a person's tobacco history is a central part of any pulmonary assessment.