What is Smoking? Smoking involves burning tobacco and inhaling the smoke. This smoke contains nicotine, tar, carbon monoxide, and over 70 carcinogenic chemicals.

The limited cubic spline cut-off analysis identified critical thresholds for an increase in stroke risk at 410 units of smoke exposure, 12 mg of tar, 1.1 mg of nicotine, and 12 ppm of carbon monoxide.

A 2021 review notes that clove cigarettes often produce more tar and carbon monoxide than conventional cigarettes. These substances increase the risk of cancer and other diseases.