What is a colorless, odorless, and poisonous gas found in cigarette smoke?

Carbon monoxide is a colorless, odorless gas that is indeed found in cigarette smoke and is highly toxic. This gas is produced during the incomplete combustion of carbon-containing materials, which includes tobacco. When inhaled, carbon monoxide binds to hemoglobin in the blood, reducing the blood's capacity to carry oxygen. This results in decreased oxygen delivery to vital organs, which can lead to serious health consequences, particularly for individuals who smoke or are exposed to secondhand smoke.

Formaldehyde, while present in cigarette smoke, is not a gas that is colorless and odorless; it has a characteristic pungent smell associated with its presence. Ammonia is another component of cigarette smoke, contributing to its irritating qualities, but it is not colorless or odorless either—ammonia has a very distinct and sharp odor. Nitrogen dioxide, on the other hand, is produced from combustion processes and can irritate the respiratory system, but it is not a primary component of cigarette smoke in the same way carbon monoxide is.