Smoking Girl

A list of 599 cigarette additives, created by five major American cigarette companies, were approved by the Department of Health and Human Services in April 1994. None of these additives are listed as ingredients on the cigarette pack(s). Chemicals are added for organoleptic purposes and many boost the addictive properties of cigarettes, especially when burned.
One of the chemicals on the list, ammonia, helps convert bound nicotine molecules in tobacco smoke into free nicotine molecules. This process is known as freebasing which enhances the effect of the nicotine on the smoker.