The Effect of Floor Height on Secondhand Smoke Transfer in Multiunit Housing.

Secondhand smoke (SHS) exposure remains a major public health concern in the United States. Homes have become the primary source of SHS exposure, with elevated risks for residents of multiunit housing. Though this differential risk is well-documented, little is known about whether SHS exposure varies by floor height. The aim of this study was to examine whether SHS accumulates in higher floors of multiunit housing. Using validated passive nicotine sampling monitors, we sampled air nicotine concentrations on multiple floors of 21 high-rise (>15 floors) buildings in New York City. Within the buildings, measurements were collected in three locations: non-smoking individual apartments, hallways and stairwells. Measurements were collected in two winter and two summer waves to account for potential seasonality effects. We analyzed the percent of filters with detectable nicotine and quantified nicotine concentration (µg/m3). Higher floor levels were positively associated with both airborne nicotine measures, with some variation by location and season observed. In winter, the trends were statistically significant in apartments (floors ≤7: 0.022 µg/m3; floors 8−14: 0.026 µg/m3; floors ≥15: 0.029 µg/m3; p = 0.011) and stairwells (floors ≤7: 0.18 µg/m3; floors 8−14: 0.19 µg/m3; floors ≥15: 0.59 µg/m3; p = 0.006). These findings can inform interventions to mitigate the SHS exposure of residents in multiunit housing.