Indoor air quality at five site museums of Yangtze River civilization

The Yangtze River civilization, dating back to more than 7 thousand years ago, is one of the most historic culture aggregates in China. For long-term conservation of archaeological artifacts and historical ruins along the Yangtze River, indoor air quality at five site museums were investigated during summer and winter. Unstable microclimate conditions were observed at all five museums. The maximal seasonal variations in temperature and relative humidity were 25.7 °C and 40.0%, respectively. The mass concentration of PM_2.5 inside the museums remained at high levels, ranging from 33.9 to 79.6 μg/m³ in winter and from 52.8 to 113.0 μg/m³ in summer. Organic matter (OM) constituted a major fraction (39.3%-53.9% in summer, 22.1%-27.8% in winter) of total PM_2.5. The results showed that besides short-term fluctuation and seasonal variation in microclimate conditions, infiltration of gaseous and particulate air pollutants should be of increasing concern at museums in Southern China.