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.