Infiltration Characteristic of Outdoor Fine Particulate Matter (PM2.5) for the Window Gaps

Even if closing windows, atmospheric PM2.5 can still penetrate into indoor through gaps of windows, then causing the indoor environment polluted. In order to evaluate the influence of windows with different airtightness levels on infiltration characteristic of PM2.5, a longitudinal monitoring regarding indoor and outdoor PM2.5 mass concentrations and meteorological parameters have been carried out in two offices located in Beijing, China from 1st July to 2nd November, 2014. Research results showed that when windows and mechanical ventilation were closed and there were no obvious indoor particle sources, the indoor PM2.5 mass concentration, the I/O ratio and the air exchange rate causing of window gaps of the sample site with lower airtightness window were higher than the one with higher window airtightness. Furthermore, the I/O ratio and air exchange rate were both positively correlated with outdoor wind speed, while negatively correlated with outdoor relative humidity. The findings can provide meaningful reference to further research on influence of atmospheric PM2.5 on indoor environment and help further develop approaches to control outdoor originated indoor PM2.5.