多相复杂系统国家重点实验室知识库

Indoor and outdoor particulate matter 2.5 (PM2.5) concentrations were monitored in seven sampling sites: basketball stadium, hotel, shopping centre, research centre, commercial office, apartment building and villa, to determine the indoor and outdoor relationship of PM2.5 mass concentration in the central area of Beijing from February 2014 to March 2014. The influence of four types of ventilation systems on indoor to outdoor (I/O) ratio of PM2.5 concentration was evaluated. The measured results show that the mean I/O ratio of the seven locations was 0.36 when the outdoor PM2.5 concentration was more than 150 mu g/m(3), and 1.1 when the outdoor PM2.5 concentration was less than 100 mu g/m(3), which implies that people's activities could be the most likely factor rather than outdoor sources for elevated indoor PM2.5 levels. The average I/O ratio was 0.69 for public buildings and 0.94 for residential homes, which illustrates that indoor PM2.5 concentrations could be dominated by outdoor sources for residential homes. Approximately 90% of the outdoor particles were removed in public buildings equipped with fan-coil unit with air cleaning plus fresh air system. The results demonstrate the need to improve indoor air quality by using a proper ventilation system with air cleaning.