Study on Species, Concentrations and Source Apportionment of Volatile Organic Compounds (VOCs) in Indoor Air of Office Buildings
Keywords:
Indoor air quality, Volatile organic compounds VOCs, Formaldehyde, Positive Matrix Factorization (PMF)Abstract
This study is a quantitative research employing a field measurement and applied analytical approach to investigate the types, concentrations, and source contributions of volatile organic compounds (VOCs) in indoor air of Bangkok office. Air samples were collected from three office buildings with different characteristics: a new building (Office A), an old building (Office B), and a renovated old building (Office C). Sampling was conducted both indoors and outdoors for six consecutive days in each building, covering working days and weekends, during February to August 2023. The sampling and analytical procedures followed the U.S. Environmental Protection Agency (U.S. EPA) standard methods: Method TO-15 (Canister–Preconcentrator–GC/MS) for general VOCs and Method TO-11A (DNPH–HPLC) for carbonyl compounds. The collected data were statistically analyzed using the Positive Matrix Factorization (PMF) model to identify and quantify VOC emission sources.
The results revealed that the total VOC concentrations indoors ranged from 72.81 to 148.35 ppb, which were significantly higher than those outdoors (33.07–76.17 ppb). Among the buildings, Office A had the highest average indoor concentration (148.35 ppb), followed by Office C (118.52 ppb), while Office B showed the lowest (72.81 ppb). The predominant indoor VOCs were formaldehyde (32–35% of total VOCs) and ethanol (12–20%), whereas outdoor VOCs were dominated by ethanol (24–26%) and formaldehyde (15–20%). PMF analysis identified three main indoor emission sources: (1) cleaning products (60–61% in Offices A and C), (2) building materials and wooden furniture (46% in Office B), and (3) paints and adhesives (14–26%), with variations depending on the building’s age and usage characteristics. For outdoor environments, the major sources were vehicle exhaust (42–52%), background concentrations (16–31%), biogenic emissions (13–28%), and cooking activities (19% near Office C).
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