ABSTRACT
Air pollution induces a variety of human ailments, including respiratory, circulatory, neurological, digestive, and urinary organ problems, as well as cancer. Volatile organic compounds (VOCs) have been primary air pollutants in indoor and urban environments, adverse to human health and the environment. The air purifier was developed to reduce indoor airborne pollutants, including particles. The discussion includes properties of air purified, photocatalytic properties on different airborne contaminants, the effect of greenhouse gases (COx, NOx, SOx) on the air purifier, classifying the effect of photocatalyst materials on ground level smoke, ozone, smogs, viruses, and bacteria. Research on air filters to overcome the Covid 19 virus outbreak is increasingly popular. Current possible materials and performance for photocatalytic air purifiers using bismuth (Bi), WO3, silver (Ag), C3N4, and oxide materials. Some materials with different variations are found with the best product and removal efficiency results. The discussion is to elucidate the possible material for an air filter (air purifier). In addition, HEPA Filter with an excellent filter for dealing with mold, dust, germs, viruses, and other gases in indoor and outdoor systems is also discussed. These filters are made up of multiple layers of filter material and can eliminate at least 99.97% of particles larger than 3 microns. Finally, TiO2 as a famous photocatalytic material is also discussed as a filter precursor in several investigations which is ideal for germs, smoke, and smells. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.