Mr. Slade taught many of his colleagues in Virginia and North Carolina the new technique as well, and further refinements by others led to what is recognized today as the flue-curing process. The high sugar content of flue-cured tobacco resulted in a more acidic smoke than varieties containing less sugar, such as those used to make cigars. This characteristic results in nicotine being ionized and held in solution in the aerosol droplets of smoke. A contrasting approach to the development of a nicotine delivery device that facilitated inhalation was developed on Java just after the turn of the 20th century. Cloves, which contain the potent local anesthetic eugenol, came to be mixed with dark tobaccos.
Clove cigarettes are today the major delivery device used in Indonesia for inhaled nicotine.
Machinery to make cigarettes inexpensively, tobacco blends that facilitated inhalation, modern railroad networks, mass media advertising methods, the safety match, and, quite probably, the promotion of competition fostered by the dissolution of the Tobacco Trust in 1911, combined, by the time RJ Reynolds introduced Camel cigarettes in 1913, to create the conditions that led to the cigarette epidemic. By midcentury, health concerns about cigarettes led manufacturers to modify their products in ways that provided the appearance of safety. Without regulatory oversight, manufacturers added filters and made brazen claims of health benefit. Among the prominent filters of the 1950s was the Micronite Filter for Kent cigarettes. The original Kent filter was crocidolite asbestos, and the company had reports from two independent electron microscopy labs by 1954 that asbestos was present in the smoke from these cigarettes.