Organic Vapor Emission of Household Indoor Nonphotocatalytic Paints: The Importance of Natural and Artificial Light

Interior paints are a significant source of both volatile and very volatile organic compounds (VOCs and VVOCs, V/VOCs) in a newly painted indoor environment. Natural and artificial light sources such as sunlight and fluorescence light may influence the emissions of V/VOCs from photocatalytic paints. However, the effect of indoor light sources on nonphotocatalytic paint has not been extensively explored. Here, we conducted laboratory simulations of water-based acrylic paint (WBP) and solvent-based nitrocellulose paint (NP) in indoor air and found that total V/VOC concentrations increased under different lighting conditions, with the highest increase under LED lights, followed by fluorescent and ultraviolet (UV) lights. The temperature increased by around 2 °C during illuminations and promoted the release of V/VOCs. However, our predictions of V/VOC emissions with temperature rise suggested that for both WBP and NP, certain VOC species (e.g., toluene) underwent photodegradation simultaneously under fluorescent and UV lights. Secondary formation of formaldehyde was even observed for NP under the influence of fluorescent or UV lights. These laboratory findings were corroborated by investigations in a newly painted environment. The observed effects of indoor lights on V/VOC emissions and consumption from nonphotocatalytic paints enhance our understanding of indoor air quality, especially in newly renovated spaces.