Spectral selective composite mask media for personal cooling and efficient PM 2.5 removal

Face masks are commonly used to protect an individual’s respiratory system from inhaling fine particulate matter (PM 2.5 ) in polluted air, as well as the airborne pathogens, especially during the ongoing coronavirus disease 2019 (COVID-19) pandemic. However, all conventional masks with anti-PM 2.5 function suffer from insufficient facial thermal comfort, particularly in a hot and humid environment. Herein, we demonstrated a novel infrared-transmittance visible-opaque PM 2.5 media for radiative cooling utilizing rutile titanium dioxide particle-embedded polyamide 6 (PA6-TiO 2 ). The transmission of visible light and infrared and PM 2.5 removal performance of composite media containing a variety of microstructures, such as TiO 2 particles of varying sizes, shapes, and contents, were numerically examined to determine the optimal ranges. Then the PA6-TiO 2 media was effectively electrospun by controlling the arrangement of fibers and the morphology of TiO 2 particles. By transmitting more than 85% of the thermal radiation from the human body and selectively blocking solar irradiance, the developed PA6-TiO 2 (flower-shaped) media cooled the simulative skin by 10.3°C as compared with commercial masks under strong solar irradiance. Additionally, they demonstrated a high PM 2.5 removal efficiency of 95.3%, a low air resistance of 22.5 Pa (at 5.3 cm/s), and a sound water vapor transmission rate of 0.0169 g cm −2 h −1 . This study presents an effective strategy for making thermally comfortable anti-PM 2.5 masks, which will significantly benefit the public health prevention and control.