ESCC	exclusive smokers of conventional cigarettes
DU	dual use of conventional cigarettes and e-cigarettes
DUs	dual users of conventional cigarettes and e-cigarettes
COPD	chronic obstructive pulmonary disease
CRP	human c-reactive protein
CVD	cardiovascular disease
GCF	gingival crevicular fluid
3-HPMA	Urinary 3-hydroxypropyl mercapturic acid, a major metabolite of acrolein
TSNA	Tobacco-specific N-nitrosamines
PAH	polycyclic aromatic hydrocarbons
HDL	high density lipids
GTT	glucose tolerance test
HbA1c	glycosylated hemoglobin
HPMA	N-acetyl-S-3-hydroxypropylcysteine, a metabolite of acrolein (VOC)
MHB3	a metabolite of 1,3-butadiene (VOC)
NNAL	4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol, the principal metabolite of the lung carcinogen NNK (TSNA)
PMA	benzene
VOC	Volatile organic compounds