Assessment of Reduction in Indoor PM2.5 of Outdoor Origin by using Nanofiber Filters as Window Screens

Abstract

Exposure to outdoor PM2.5 (particulate matters with an aerodynamic diameter less than 2.5 μm) is associated with adverse health effects. Outdoor PM2.5 can penetrate into buildings through infiltration and ventilation. Recently, researchers from nanoscience and nanotechnology have developed various nanofiber filters with high PM2.5 removal efficiency and relatively low air resistance. There is a potential to use these nanofiber filters as the window screens in order to filter out the outdoor PM2.5 while still ensure the natural ventilation. This study proposed a method to assess the reduction of indoor PM2.5 of outdoor origin (Cp,in) by using nanofiber filters as window screens in real residences. The Monte Carlo method was utilized to account for the variety of the PM2.5 reduction among different residences. Two newly developed nanofiber filters has been evaluated for Beijing residences. The selected nanofiber window screens could reduce the mean value of the annual average indoor PM2.5 of outdoor origin by 65–67%. However, the annual average air exchange rate of the residences equipped with nanofiber window screens, which range 0.23 to 0.30 h-1, would be far below the national standard.