From the National Survey on Drug Use and Health:
How old were you the first time you used snuff?
How old were you the first time you used chewing tobacco?
Initiation of smokeless tobacco use in the 12 months prior to date of interview was identified by examining the youth’s interview date, birth date, and initiation date of first tobacco use. Smokeless tobacco use includes snuff and chewing tobacco. Persons who responded that they have used either snuff or chewing tobacco for more than 12 months are not included in this measure.