Strength of smoke-free air laws and indoor air quality

Introduction: Smoke-free air laws have been implemented in many Kentucky communities to protect the public from the harmful effects of secondhand smoke exposure. The impact of different strengths of smoke-free air laws on indoor air quality was assessed. Methods: Indoor air quality in hospitality venues was assessed in seven communities before and after comprehensive smoke-free air laws and in two communities only after partial smoke-free air laws. One community was measured three times: before any smoke-free air law, after the initial partial law, and after the law was strengthened to cover all workplaces and public places with few exemptions. Real-time measurements of particulate matters with 2.5 μm aerodynamic diameter or smaller (PM_2.5) were obtained. Results: When comprehensive smoke-free air laws were implemented, indoor PM_2.5 concentrations decreased significantly from 161 to 20 μg/m³. In one community that implemented a comprehensive smoke-free law after initially passing a partial law, indoor PM_2.5 concentrations were 304 μg/m³ before the law, 338 μg/m³ after the partial law, and 9 μg/m³ after the comprehensive law. Discussion: The study clearly demonstrated that partial smoke-free air laws do not improve indoor air quality. A significant linear trend indicated that PM_2.5 levels in the establishments decreased with fewer numbers of burning cigarettes. Only comprehensive smoke-free air laws are effective in reducing indoor air pollution from secondhand tobacco smoke.