Outdoor-to-indoor transport of ultrafine particles: Measurement and model development of infiltration factor

Chen Chen; Mingyao Yao; Xu Luo; Yulin Zhu; Zhaoyang Liu; Hanchen Zhuo; Bin Zhao

doi:10.1016/j.envpol.2020.115402

Outdoor-to-indoor transport of ultrafine particles: Measurement and model development of infiltration factor

Environ Pollut. 2020 Dec:267:115402. doi: 10.1016/j.envpol.2020.115402. Epub 2020 Aug 13.

Authors

Chen Chen¹, Mingyao Yao¹, Xu Luo¹, Yulin Zhu¹, Zhaoyang Liu², Hanchen Zhuo¹, Bin Zhao³

Affiliations

¹ Department of Building Science, School of Architecture, Tsinghua University, Beijing, 100084, China.
² Center for Statistical Science, Tsinghua University, Beijing, 100084, China; Department of Industrial Engineering, Tsinghua University, Beijing, 100084, China.
³ Department of Building Science, School of Architecture, Tsinghua University, Beijing, 100084, China; Beijing Key Laboratory of Indoor Air Quality Evaluation and Control, Tsinghua University, Beijing, 100084, China. Electronic address: binzhao@tsinghua.edu.cn.

PMID: 32858436
DOI: 10.1016/j.envpol.2020.115402

Abstract

Ambient ultrafine particles (UFPs: particles of diameter less than 100 nm) cause significant adverse health effects. As people spend most time indoors, the outdoor-to-indoor transport of UFPs plays a critical role in the accuracy of personal exposure assessments. Herein, a strategy was proposed to measure and analyze the infiltration factor (F_inf) of UFPs, an important parameter quantifying the fraction of ambient air pollutants that travel inside and remain suspended indoors. Ninety-three measurements were conducted in 11 residential rooms in all seasons in Beijing, China, to investigate F_inf of UFPs and its associated influencing factors. A multilevel regression model incorporating eight possible factors that influence infiltration was developed to predict F_inf and F_infSOA (defined as the ratio of indoor to outdoor UFP concentrations without indoor sources, but with indoor secondary organic aerosol (SOA) formation). It was found that the air change rate was the most important factor and coagulation was considerable, while the influence of SOA formation was much smaller than that of other factors. Our regression model accurately predicted daily-average F_inf. The annually-averaged F_inf of UFPs was 0.66 ± 0.10, which is higher than that of PM_2.5 and PM₁₀, demonstrating the importance of controlling indoor UFPs of outdoor origin.

Keywords: Ambient air pollution; Human exposure; Indoor air quality; Particulate matter.

MeSH terms

Air Pollutants* / analysis
Air Pollution, Indoor* / analysis
Beijing
China
Environmental Monitoring
Humans
Particle Size
Particulate Matter / analysis

Substances

Air Pollutants
Particulate Matter