Humans spend approximately 80% of their time indoors daily, making indoor air quality crucial to human health. Indoor air pollutants often coexist in various forms, including particulate matter, volatile organic compounds (VOCs), and microorganisms. Consequently, a systematic and comprehensive purification solution is essential for addressing indoor air pollutants. Air purifiers, as typical passive purifiers, are vital for the efficient removal of indoor air pollutants. Compared to traditional fiber filter materials, membrane materials offer superior particulate filtration performance and lower gas resistance. This exceptional performance allows membranes to replace high-efficiency particulate air (HEPA) filters in household ventilation systems. This Chapter first introduces the sources and hazards of indoor air pollutants. It then reviews existing air purification technologies, such as chemical absorption, adsorption, photocatalytic technology, and low-temperature plasma technology. Finally, it discusses the application of membrane materials in air purifiers, fresh air systems, and anti-smog window screens.