Secondhand smoke regularly infiltrates 25% of nonsmokers' apartments in Westchester. It contains higher levels of carcinogens than smoke inhaled directly. Ventilation and air filtration systems cannot control secondhand smoke spread. A smoke-free policy is the only effective way to protect nonsmokers from the health risks of secondhand smoke in multi-unit housing settings like apartments. Several cities have implemented smoke-free policies for all multi-unit housing to improve residents' health.