All in all, step one,039,249 adolescents aged twelve–sixteen age out-of one hundred regions which had presented a couple of studies anywhere between 1999 and you may 2019 were used so you’re able to estimate the fresh new development about incidence of smokeless using tobacco. From , 66 out-of a hundred places conducted a couple of studies, 23 presented around three surveys, 10 presented four studies, and something conducted 15 surveys; 83 regions held new surveys during the federal height, and you will 17 places held this new studies within local or subregional level (A lot more document step 1: Table S4). (suite…)