Table 1 Descriptive characteristics of participant groups in this study

Socio-demographic factors

 Age (years) (n = 348)

 BMI (kg/m²) (n = 345)

 Smoking (pack-years) (n = 313)

0 (0, 0.0001)

1.20 (0.38, 3.15)

0.0013 (0.0006, 0.0027)

 Sex (% male) (n = 350)

 Ethnicity (% white) (n = 344)

 Education (% higher education) (n = 344)

 Occupation (% unemployed) (n = 344)

 Household smoking (% yes) (n = 346)

 Recreational drug use (% yes) (n = 346)

 Cannabis (% yes) (n = 346)

Estimated cell type proportions (%) (n = 350)

 Buccal

 Bcell

 CD4T

 CD8T

 Granulocytes

 Mono

 NK

Vaping characteristics

 E-cigarette device (n = 113)

N/A

N/A

  Cigalike (1st generation)

  Tanks (2nd generation)

  Mods (3rd generation)

  Pods (4th generation)

  Other

 Frequency of use (% daily) (n = 113)

 Device contains nicotine (% yes) (n = 112)

 Increased nicotine concentration in the past (% yes) (n = 113)

 Length of time vaping (% > 1 year) (n = 113)

 Nicotine content (mg/ml) (n = 112)

N/A

N/A

 Liquid per day (ml) (n = 108)

Smoking characteristics

 Cigarettes or roll-ups (% roll ups) (n = 117)

 Frequency of smoking (% daily) (n = 117)

 Length of time smoking (% > 5 years) (n = 114)