“…The inverse correlation between vaping and smoking is consistent with other findings: Frequent EC use is associated with lower self‐reported cigarette smoking (Biener & Hargraves, ; Brose, Hitchman, Brown, West, & McNeill, ; Giovenco & Delnevo, ; Hitchman, Brose, Brown, Robson, & McNeill, ; Levy, Yuan, Luo, & Abrams, ; Subialka Nowariak, Lien, Boyle, Amato, & Beebe, ). Given the inverse correlation between EC use and CO levels, future research should determine if directly reinforcing EC use produces reductions in CO.…”