The study has a per-factor breakdown here: https://www.bmj.com/content/368/bmj.l6669 https://www.bmj.com/content/368/bmj.l6669 "Ever smoking" looks like "smoke

The study has a per-factor breakdown here: https://www.bmj.com/content/368/bmj.l6669 https://www.bmj.com/content/368/bmj.l6669 "Ever smoking" looks like "smoked any amount but doesn't presently" rather than "occasional smoker through present", and the lowest bucket for current smokers is 1-14 cigarettes per day. <10 is, I suppose, 1/3 of a cigarette per day. "Ever" and "1-14" show clear and substantial health effects, which isn't promising, but <10/month looks to be below any of the actual measured brackets.