Table 2.

Cross-Sectional Study Characteristics and Outcomes

Cross-sectional	N	Frequency of use	Difference between vaping and smoking				Difference between nonuse and vaping				Risk of Bias (Biocross)
			NNAL	NNN	NAB	NAT	NNAL	NNN	NAB	NAT
Bustamante 201834	Smoking n = 20 Vaping n = 20 Nonuse n = 19	Daily Daily <100 cigs in lifetime	95%↓ 85%↓ (saliva)	99%↓			99%↓ 98%↓(saliva)	0%98%↓ (saliva)			15/20
Carroll 201847	Smoking n = 27 Vaping n = 23	Daily and CO > 6 Daily and CO =<6ppm	91%↓								13/20
Coleman 202148	Smoking n = 84 Vaping n = 27	Some days/every day Some days/every day	Pregnant 92%↓ Non-pregnant 93%↓								12/20
Dai 202149	Vaping n = 222 Nonuse n = 2849	Some days/every day					W resp 71%↓ W/o resp 68%↓	W resp 22%↓ W/o 33%↓			15/20
Goniewicz 201850	Smoking n = 2411 Vaping n = 247 Nonuse n = 1655	Some days/every day Some days/every day Never smoked/vaped	98%↓	71%↓	91%↓	97%↓	81%↓	45%↓	25%↓	8%↓	13/20
Olivieri 202052*	Smoking n = 62 Vaping n = 132	Daily Some days/every day	Tank 61%↓ Cartridge 52%↓								15/20
Perez 202151	Smoking n = 961 Vaping n = 109 Nonuse n = 787	Some days/every day Some days/every day Never smoked/vaped	98%↓				82%↓				16/20
Shahab 201755	Smoking n = 37 Vaping n = 37	Daily and CO verified Weekly and CO verified	97%↓		84%↓	95%↓					16/20
Smith54	Smoking n = 127 Vaping n = 124 Nonuse n = 110	Daily and CO verified Daily and CO verified No use for 6 months	92%↓		82%↓	97%↓	72%↓		13%↓	20%↓	10/20
Xia 202153	Daily smoking n = 3176 Daily vaping n = 152 Ex-smoking n = 559		98%↓	62%↓	91%↓	96%↓	67%↓	58%↓	24%↓	18%↓	15/20
	Non-daily smoking n = 2400 Non-daily vaping n = 106 Never-smoking = 1563		71%↓	29%↓	52%↓	63%↓	76%↓	14%↓	8%↓	15%↓

^*Denotes studies funded by the tobacco industry CPD = cigarettes per day, CO = carbon monoxide, M = mean, SD = standardised deviation, ↓ indicates % lower among people who vaped compared to smoked, or % lower among non-users compared to people who vape, W = with respiratory symptoms, W/o = without respiratory symptoms Unless otherwise stated, results indicate urinary levels. Unless otherwise stated, results indicate urinary levels.