Harvard School of Public Health [3] researchers combed through tobacco industry documents [4] to find out why the industry adds menthol [5] to cigarettes, and why cigarette brands have differing levels of menthol. Researchers found that tobacco companies use menthol's anesthetic [6] effect to mask the harshness of the smoke and ease throat pain for beginning smokers [7]. Once smokers are addicted [8], according to documents, they seek cigarettes with increasing levels of menthol to maintain the sensory effects. Tobacco companies respond by making cigarette brands with low levels of menthol for starters [9], and brands with higher menthol levels for veteran smokers. R.J. Reynolds [10] calls the Harvard study propaganda [11], and says it is aimed at promoting a federal ban on menthol [12]. The study [13] was published online ahead of print at the Web site [14] of the American Journal of Public Health [15].