Indoor volatile organic compounds in existing densely occupied education buildings of four universities: Source apportionment

Abstract

Human-related emissions had been proved to be crucial sources of indoor volatile organic compounds (VOCs) in densely occupied spaces. However, more work was needed on quantifying human emissions on indoor VOCs in actual densely occupied spaces. This study intended to investigate possible emission sources and their contributions to indoor target VOC concentrations in densely occupied spaces. Eighteen targeted VOCs in 97 existing densely occupied rooms of four universities issued by another accompanied study were further identified for their source apportionment. A receptor model using positive matrix factorization (PMF) coupled with source information of those VOCs was applied to quantify the major sources in those densely occupied education rooms. The results show that five sources of VOCs were identified, including human body emission, indoor nonoccupant emissions, human activities, ventilation/infiltration, and chemical reactions, contributing 24.59%, 13.01%, 20.34%, 32.02% and 10.04%, respectively. Among them, human-related emission sources, including human bodies, human activities and chemical reactions, were characterized by a large mass fraction of isoprene, acetone, nonanal, geranyl acetone, 6-methyl-5-hepten-2-one (6-MHO), d-limonene, decanal, acetone, isoprene and benzene, 1,4-dichloro-. This study could be a better understanding of the characterization of indoor VOC pollution in densely occupied spaces.