Research on Evaluation Index of Indoor PM2.5 Purification Effect Yiwen Jian, Xundong Gu, Ruiming Guo, Mengmeng Bian and Zijia Liu E3S Web Conf., 356 (2022) 05061 Published online: 31 August 2022 DOI: 10.1051/e3sconf/202235605061