The multifunctional air filter, which can provide low resistance to airflow, was prepared from polyacrylonitrile (PAN) nanofibers (NFs) by impregnating zinc oxide (ZnO) nanoparticles (NPs) with photocatalytic activity. Incorporation of ZnO NPs improved the surface roughness and electrostatic charge of electrospun NFs. The PAN/ZnO composite filter with 12 wt%-ZnO showed a filtration efficiency of 98.8% and a pressure drop of 48 Pa for 300 nm aerosol particles, resulting in a quality factor of 0.092 Pa −1. In addition, PAN/ZnO composite exhibited excellent photocatalytic activity in methylene blue (MB) decomposition at 100 and 70.2% efficiencies, respectively, under UV and visible light. K E Y W O R D S applications, separation techniques, synthesis and processing techniques 1 | INTRODUCTION According to the World Health Organization, exposure to air pollutants ranks high among the causes of human mortality (WHO, 2020). Specifically, outdoor air pollution was estimated to cause more than 4 million premature deaths annually. Such magnitude is attributed to inhalation of fine dust particles (otherwise called PM 2.5), associated with several lungs, heart, and respiratory diseases. 1-3 Although much efforts have been devoted to ameliorating PM pollution, the levels of tropospheric PM 2.5 in major cities are still unacceptably high (WHO). Therefore, active researches continue to find the most effective technologies to control PM pollution. Usually, PM is released from industrial, vehicular, and combustion processes, accompanied by some gaseous pollutants such as carbon monoxide (CO), nitrogen oxides (NOx), Sulfur dioxide (SO 2), and volatile organic compounds (VOCs). 3 In particular, several adverse