Can nasal filters be used to reduce personal exposure against nano- to submicron-sized environmental tobacco smoke (ETS) aerosols?

Environmental tobacco smoke (ETS) contains large amounts of nano- to submicron-sized aerosols, which can be suspended in the indoor air for a long time and are easily inhaled by nonsmokers causing various diseases. In recent years, various types of nasal filters have been increasingly emerging on the market, claiming to be effective in filtering ETS aerosols. In order to test the real protection level of those nasal filters, this study independently builds a nasal filter simulation test system, separately takes mainstream smoke (MS) and sidestream smoke (SS) aerosols as the test mediums (ETS consists of MS and SS), and comprehensively tests the filtration efficiency, inspiratory resistance and quality factor of five nasal filters (four commercially available and one self-made from N95 filtering facepiece respirator) at two flow patterns (constant flow and simulated human breathing flow) and three flow rates (15, 30 and 50 L/min). Results show that the filtration efficiencies of the four commercial nasal filters are all less than 20% for both MS (98% aerosols lie in 85-380 nm) and SS aerosols (94% lie in 65-200 nm), while the inspiratory resistance analysis confirms that to avoid open-mouth breathing, the tested nasal filters can only be used at rest or during light activity. The findings reveal that, to effectively protect against ETS aerosols, manufacturers should further develop high-efficiency nasal filters with low-resistance. This study may serve as a reference for establishing testing standards on nasal filters. Copyright (c) 2022 American Association for Aerosol Research