Fig. 1.

Crude and adjusted association between nicotine product use and respiratory wheezing.

Sample sizes by nicotine use group were: Exclusive e-cigarette user (n = 520), Never smoker/e-cigarette users (n = 6,748), Light smoker < 10 cigarettes/day (n = 561), Moderate smoker 10–19 cigarettes/day (n = 708), and Heavy smoker ≥ 20 cigarettes/day (n = 407). A further 56 exclusive cigarette smokers with missing data on daily cigarette consumption were excluded from this model (analytic N = 8944). Adjusted estimates account for age group, sex, deprivation, longstanding illness, doctor-diagnosed COPD, doctor-diagnosed asthma, self-rated general health, alcohol consumption status, age of smoking initiation, and second-hand smoke exposure