Remediating Thirdhand Smoke Pollution in Multiunit Housing: Temporary Reductions and the Challenges of Persistent Reservoirs

Introduction. Toxic tobacco smoke residue, also known as thirdhand smoke (THS), can persist in indoor environments long after tobacco has been smoked. This study examined the effects of different cleaning methods on nicotine in dust and on surfaces. Aims and Methods. Participants had strict indoor home smoking bans and were randomly assigned to: dry/damp cleaning followed by wet cleaning 1 month later (N = 10), wet cleaning followed by dry/damp cleaning (N = 10) 1 month later, and dry/damp and wet cleaning applied the same day (N = 28). Nicotine on surfaces and in dust served as markers of THS and were measured before, immediately after, and 3 months after the cleaning, using liquid chromatography with triple quadrupole mass spectrometry (LC-MS/MS). Results. Over a 4-month period prior to cleaning, surface nicotine levels remained unchanged (GeoMean change: -11% to +8%; repeated measures r = .94; p < .001). Used separately, dry/damp and wet cleaning methods showed limited benefits. When applied in combination, however, we observed significantly reduced nicotine on surfaces and in dust. Compared with baseline, GeoMean surface nicotine was 43% lower immediately after (z = -3.73, p < .001) and 53% lower 3 months later (z = -3.96, p < .001). GeoMean dust nicotine loading declined by 60% immediately after (z = -3.55, p < .001) and then increased 3 months later to precleaning levels (z = -1.18, p = .237). Conclusions. Cleaning interventions reduced but did not permanently remove nicotine in dust and on surfaces. Cleaning efforts for THS need to address persistent pollutant reservoirs and replenishment of reservoirs from new tobacco smoke intrusion. THS contamination in low-income homes may contribute to health disparities, particularly in children.

Automated summary

This study found that different cleaning methods alone have limited effectiveness in removing nicotine residue indoors. However, combining dry/damp cleaning with wet cleaning significantly reduced nicotine levels on surfaces and in dust. While cleaning interventions reduced nicotine contamination, they did not permanently eliminate it from indoor environments.