Thirdhand Tobacco Smoke: A Systematic Review of Evidence for Its Persistence, Identification, and Effects in the Indoor Environment

Abstract

Tobacco smoke can affect indoor air quality on both short and long time scales. Active tobacco smoking and secondhand smoke exposure are known to be harmful to human health and to degrade indoor environmental quality. The potential effects of thirdhand tobacco smoke (THS) on health and indoor air are less well characterized. This review summarizes field measurements and laboratory research to highlight the ubiquity, persistence, and evolution of THS in indoor environments. We assess indoor nicotine concentrations across air, dust, and surfaces and propose nicotine thresholds to classify indoor environments independent of self-reported smoking designation. Frequently reported THS tracers and biomarkers are evaluated to support targeted THS monitoring and exposure assessment. We examine major THS exposure pathways and exposure levels from a metabolic perspective, informed by finger nicotine measurements. We discuss the environmental effects of THS, including chemical transformations and transport. Finally, we evaluate remediation strategies and identify key opportunities to advance the field of THS research.