Search

Indoor pollution of manmade semivolatile organic compounds (SVOCs) such as phthalates are a growing threat to human health. Herein we summarize the dust-phase phthalate concentrations in Chinese residences reported from 2011 to 2021 and simulate corresponding airborne concentrations based on equilibrium models. The simulation considers seasonal and regional variations in indoor temperature and PM2.5 concentration, in contrast to the common practice of using constant values. Results show that variations in these two environmental factors lead to up to ten- and six-fold variations in the monthly median gas- and particle-phase concentrations of phthalates, respectively, in residences in individual climate zones. For higher-vapor-pressure species di-n-butyl phthalate and di-isobutyl phthalate, the resultant seasonal and regional variations in aggregate non-diet intake can reach six- and three-fold, respectively. These results have important implications on exposure assessment of SVOCs and epidemiological evaluation of their health effects.

As a typical representative city of China’s hot and humid climate zone, Chongqing has an average annual relative humidity of 70% - 80%. Continuous online monitoring of indoor air quality (IAQ) were conducted in more than 20 residents of Chongqing city. It was found that the apartments in the area had excessive indoor absolute humidity in summer (far exceed the ASHRAE recommended comfort limit—12g/kg) and excessive indoor relative humidity in winter and transitional seasons. It is necessary to dehumidify the outdoor intake air during the summer and decrease the indoor related humidity during the winter and transition seasons. Based on the above two points, it is proposed to adopt a fresh air system with dehumidification function in Chongqing, which can remove excessive absolute humidity caused by outdoor air in high humidity month. The fresh air system, which changes natural ventilation to mechanical ventilation, increase indoor insulation effect and reduce relative humidity.

Mechanical ventilation system provides a more reliable, controllable, and comfortable way of ventilation than natural ventilation through an opened window. However, the operation of mechanical ventilation system cost energy. This study investigated the usage of natural and mechanical ventilation in 46 apartments in ten cities across five different climate zones in China by on-site monitoring and questionnaire survey. On average, the daily natural and mechanical ventilation durations were 11 hours and 7.2 hours, respectively. Large differences existed among climate regions and seasons. From north to south, as the climate became warmer, the usage of natural ventilation increased. From seasonal perspectives, natural ventilation duration was the longest in summer and the shortest in winter. The trend of mechanical ventilation usage was opposite to that of natural ventilation. Generally, as the outdoor air temperature increased, the duration of natural ventilation increased and the duration of mechanical ventilation decreased. This study proposed an outline to use thermal comfort, health, and energy saving as three motivations to analyze ventilation behaviors. Based on the obtained results, suggestions were made for achieving healthy, thermally comfortable, and energy efficient ventilation in residential buildings.