OBJECTIVE: To explore the association of hookah use on the age of asthma onset among adults who were asthma/COPD free and who did not use cigarettes, cigars, electronic cigarettes or smokeless tobacco prior to asthma onset. METHODS: Secondary data analyses were conducted of the waves 1-6 (2013-2021) of the US nationally representative Population Assessment of Tobacco and Health Study among adults (>
18 years). The four hookahs use exposures evaluated were (1) past 30-day (P30D) hookah use at the first wave of participation, (2) total number of waves before asthma onset in which adults reported P30D hookah use, (3) total number of years since first hookah use, and (4) average length of hookah sessions. Lower and upper age limits were estimated using the age reported at the first wave of participation and the number of weeks between follow-up waves until asthma was first reported or censored. Associations of the exposures on the age of asthma onset were estimated using weighted interval-censoring-Cox-regression. RESULTS: The total sample size for analysis was 5,768, representing 66.6 million adults. There was a lack of statistical power to detect differences in the age of asthma onset by (1) P30D hookah use (Adjusted Hazard Ratio (AHR) 3.77, 95CI%: .90-15.71). There was an association between (2) total number of waves of P30D hookah use (AHR 1.72, 95% CI 1.28-2.30), (3) total number of years since first hookah use (AHR 2.94, 95% CI 1.36-6.36), and (4) average length of hookah sessions (AHR 4.52, 95% CI 1.61-12.67) with the age of asthma onset. Females and Hispanics with over one year since first hookah use had higher risk of earlier age of asthma onset. CONCLUSION: Prevention and cessation programs for adults who use hookah are needed to educate the public, protect public health, prevent adverse health outcomes, and motivate hookah users to stop.