Abstract
Human exposure to volatile organic compounds (VOCs) indoors is receiving increasing attention. Formaldehyde (HCHO) is the most common VOC emitted from household materials and is associated with many health risks, including sick building syndrome. In this study, a simple box model was developed and applied to help understand the fate and degradation mechanisms of HCHO in the indoor environment. The model was validated using observations from an air handling system under different conditions. A UV/TiO2 filter reactor was installed in a closed box with the air conditioning unit. Three parameters, temperature, relative humidity, and circulation wind speed, were investigated for their effects on the performance of the air handling system. Our results show that the operation mode of the air handling system has a greater effect on the removal of HCHO than any of the air conditioning parameters. From a kinetic perspective, the removal of gaseous HCHO from a constant-volume box clearly represents a zero-order reaction. After UV irradiation with a TiO2 filter for 2 hours, the removal efficiency of gaseous HCHO increases to approximately 90%. Contributions to the removal of gaseous HCHO from natural dissipation, photodegradation, and photocatalytic oxidation decomposition are 12%, 30%, and 58%, respectively. Our results have implications for reducing indoor air pollution and reducing stress on air conditioning systems. Meeting these goals is beneficial for human health and energy conservation in modern society.
Highlights
Human exposure to indoor concentrations of volatile organic compounds (VOCs) is receiving more and more attention from scientists working in environmental medicine and public health (Hellweg et al, 2009; Collinge et al, 2013; Rosenbaum et al, 2015)
A simple box model was used to characterize the photochemical reactions of gaseous HCHO for indoor air quality management
Filter reactors with photocatalytic TiO2 nanoparticles were installed as air purifiers in this air conditioning system
Summary
Human exposure to indoor concentrations of volatile organic compounds (VOCs) is receiving more and more attention from scientists working in environmental medicine and public health (Hellweg et al, 2009; Collinge et al, 2013; Rosenbaum et al, 2015). Formaldehyde (HCHO) is one of the most common VOCs, and the World Health. The main exposure pathways for formaldehyde are inhalation of gaseous HCHO from the air or absorption of aqueous HCHO through the skin (Gelbke et al, 2014). Workplaces, including chemical plants and places where industrial chemicals are used, professional health care facilities, forensics laboratories, and mortuaries may present elevated risks of HCHO exposure (Demou et al, 2009)
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