Figure 2.

Smoking history and yearly methylation recovery. Waterfall plots showing the yearly methylation recovery in each individual, stratified according to smoking behavior groups (Never-Never = individuals who never smoked; Former-Former = individuals who formerly smoked; Current-Former = individuals who quit during the study period; and Current-Current = individuals who smoked at both baseline and follow-up). Dashed line: percentage of individuals with negative methylation recovery at follow-up. Absolute methylation recovery is shown in percentage points per year on the y-axis.