Evaluation of Secondhand Smoke Exposure in New York City Public Housing After Implementation of the 2018 Federal Smoke-Free Housing Policy.

Importance: Secondhand smoke (SHS) exposure is associated with many health conditions in children and adults. Millions of individuals in the US are currently exposed to SHS in their homes. Objective: To investigate whether a federal ban on smoking in public housing settings was associated with a decrease in indoor SHS levels in New York City public housing developments 12 months after the policy's implementation. Design, Setting, and Participants: This cohort study tracked indoor air quality longitudinally from April 2018 to September 2019 and used difference-in-differences analysis to examine SHS exposure before vs after implementation of the 2018 federal smoke-free housing (SFH) policy in 10 New York City Housing Authority (NYCHA) buildings vs 11 matched low-income buildings not subject to the SFH policy (ie, Section 8 buildings). Exposures: Federal SFH policy implementation, beginning July 30, 2018. Main Outcomes and Measures: Comparison of nicotine concentration levels from passive, bisulfate-coated filters before vs 12 months after implementation of the federal SFH policy. Secondary outcomes included changes in particulate matter less than 2.5 μm in diameter, measured with low-cost particle monitors, and counts of cigarette butts in common areas. Results: Air quality was measured repeatedly in a total of 153 NYCHA and 110 Section 8 nonsmoking households as well as in 91 stairwells and hallways. Before the SFH policy implementation, air nicotine was detectable in 19 of 20 stairwells (95.0%) in NYCHA buildings and 15 of 19 stairwells (78.9%) in Section 8 buildings (P = .19) and in 17 of 19 hallways (89.5%) in NYCHA buildings and 14 of 23 hallways (60.9%) in Section 8 buildings (P = .004). Nicotine was detected less frequently inside nonsmoking apartments overall (26 of 263 [9.9%]) but more frequently in NYCHA apartments (20 of 153 [13.1%]) than in Section 8 apartments (6 of 110 [5.5%]) (P = .04). One year after policy implementation, there was no differential change over time in nicotine concentrations measured in stairwells (DID, 0.03 μg/m3; 95% CI, -0.99 to 1.06 μg/m3) or inside nonsmoking households (DID, -0.04 μg/m3; 95% CI, -0.24 to 0.15 μg/m3). Larger decreases in nicotine concentration were found in NYCHA hallways than in Section 8 hallways (DID, -0.43 μg/m3; 95% CI, -1.26 to 0.40 μg/m3). Conclusions and Relevance: The findings suggest that there was no differential change in SHS in NYCHA buildings 12 months after SFH policy implementation. Additional support may be needed to ensure adherence to SFH policies.