Reduction of Human Exposure and Premature Deaths by Indoor PM2.5 Cleaning in Beijing, China

China is experiencing severe PM2.5 (particulate matter with an aerodynamic diameter smaller than 2.5 μm) pollution. Controlling indoor PM2.5 concentration is critical to reduce personal exposure to PM2.5 as people spend most of their time indoors. A two-dimensional Monte Carlo model was applied to estimate the PM2.5 population exposure distribution, potential impact fraction (PIF) and decrease of premature mortality by reducing indoor PM2.5 to World Health Organization (WHO) Air Quality Guideline of 10 μg/m3, WHO Interim Target levels 1, 2, and 3 of 35 μg/m3, 25 μg/m3, and 15 μg/m3 with indoor cleaning. 1376 (95% uncertainty interval (UI): 943–2438) premature deaths would be averted from controlling indoor PM2.5 to WHO Air Quality Guideline, which accounts for 0.0114% of the total population in Beijing, greater than that from controlling to WHO Interim Target 3 level (536, 95% UI: 381–952). The results showed that indoor PM2.5 control by indoor air purifier is an effective and easy method to protect human health from PM2.5 pollution.