n.
Breathing the fumes of burning plant material, especially tobacco, from a cigarette, cigar, or pipe.
Despite social and medical arguments against tobacco use, the habit has spread worldwide. Nicotine and related alkaloids furnish the psychoactive effects and, along with tar (a residue containing resins and other by-products), the negative health effects. Those effects include lung cancer , oral and throat cancers, heart disease , stroke , emphysema , chronic bronchitis , and macular degeneration . Smoking also increases the effects of other risk factors (see asbestosis ). Passive smoking (breathing the smoke from others' cigarettes) increases nonsmokers' risk of lung cancer and the risk of sudden infant death syndrome . Self-help and doctor-run programs, along with nicotine patches and gums that provide diminishing doses of nicotine, are among the aids available to help those who wish to quit smoking. Antismoking campaigns have greatly reduced smoking in the U.S. even as it rises in many other countries.