Where do smokers in Singapore smoke? A latent class analysis to classify smokers based on smoking location.

Introduction: A key lever protecting people from secondhand smoke (SHS) exposure is not sharing the same space as smokers while they smoke. However there is limited research on where exactly smokers choose to smoke, particularly in urban multi-ethnic Asian contexts. This study aims to identify distinct classes of smokers in Singapore and characterize smokers based on where they smoke.

Methods: Using responses from 1,546 participants in Wave 2 of the Singapore Smokers' Survey (2021), latent class analysis (LCA) identified distinct smoker classes based on predefined smoking location options reported for home and outside home in the past month. Multinomial logistic regression was conducted to examine differences between classes on various covariates.

Results: 3 distinct latent classes of smokers were identified: "smoke at work" (75.7%), "smoke outside home" (14.0%), and "smoke everywhere" (10.2%). Ethnicity, housing type, marital status, hardcore smoking indicator (yes vs no), smoking status (daily vs occasional), time taken to smoke first cigarette of the day after waking and perceiving family norms towards smoking habit were significant predictors of class membership. "Smoke at work" was the reference class. Those who "smoke everywhere" were more likely to be Malay, hardcore smokers and smoked their first cigarette of the day within 30 minutes of waking.

Conclusions: Observed heterogeneity amongst Singapore smokers supports implementation of more targeted interventions for both smoking cessation and protecting non-smokers from SHS exposure. Social norm change strategies may be considered, leveraging upon the roles of familial influence and ethnicity on where smokers choose to smoke.

Implications: This study identifies three distinct smoker subgroups based on smoking locations-at work, outside the home, and everywhere-offering actionable insights for targeted interventions. Workplace-based cessation efforts can focus on those smoking at work, while promoting smoke-free homes may address familial pressures in the outside-home group. For those smoking everywhere, intensive interventions are needed to reduce SHS exposure across settings. Multinomial regression reveals that familial disapproval, ethnicity, and housing type significantly influence smoking patterns, highlighting the importance of culturally tailored interventions that leverage social, familial, and environmental factors to reduce smoking prevalence and SHS exposure.