From the Cancer Institute of New Jersey:
According to Michael Steinberg, MD, MPH, FACP, a member of The Cancer Institute of New Jersey and director of the Tobacco Dependence Program, who is the senior author of the research:
“In fact, smokers who relight cigarettes may be at higher risk of lung cancer and chronic bronchitis. That is something of which policy makers need to be aware,” he notes.
From Oxford Academic:
Given that previous research has indicated that relighting cigarettes leads to increased harm, the public health implications of this smoking practice are discussed.
Sadly, I do not have permission to access the Oxford article.
When you relight a cigarette, you're breathing coal. Read about breathing coal & black lungs. If you're going to relight a cigarette it is desirable to sever the burnt end of the cigarette to remove the burnt coal. The relighting of the burnt coal causes marginally higher incidence of lung cancer compared with people who use a "cigarette snipper" (or just small scissors).
From another Quora post:
There are some simple physical truths here.
- The last few drags of a cigarette contain far more tar, as the tar from the first half has partially condensed and saturated the butt.
- There are also a lot of other toxic chemicals that do the same thing.
- Also, most of the horrible stuff in cigs is worse once it becomes oxidized (burnt.)
Although most online sources suggest, "Yes, relighting cigarettes is worse for your health", the official sources don't explain how.
The unofficial sources do conjure some possibilities, I would prefer documentation that's a bit more official.
What is the set of health concerns to consider when relighting a cigarette, compared to smoking a full never-been-lit-before cigarette? I'd assume the set would contain all the concerns of smoking in general, but what deviations exist?