1. This is a “20 pt mini review” of the scientific facts that show the harm reduction potential of electronic nicotine delivery products (ENDP). These facts are consistent across studies and coherent along the causal chain of events linking smoking to disease (CELSD) (see Figs). 2. Let’s focus on COPD, and start from the last event: “population harm”. Recent publications have shown that since the market introduction of heated tobacco products in Japan, cigarettes sales have started to decline more sharply than ever before (PMID: 31209129, 32443663). …

@ChaunceyGardner 1/10. Several clinical trials have shown that the mean nasal mucociliary clearance is negatively and significantly affected by cigarette smoking (PMIDs: 24669080, 3787531, 23615315, medrxiv.org/content/10.110…). @ChaunceyGardner 2/10. Ciliary beat frequency is also significantly affected by smoking habit. A reduced nasal ciliary beat frequency was observed among smoking individuals in a cohort study performed in a British urban population (PMID: 9669071).

@Clive_Bates @PMIScience 1/10. First, let’s be cautious about over interpretation of single studies. As always, the quantification of harm/risk reduction in humans cannot be derived from any single study, but needs an analysis of the totality of the evidence for a given product. @Clive_Bates @PMIScience 2/10. Second, definitive quantification of harm/risk reduction will come from population-level studies, including epidemiology, that take into account product use behaviors.