Real-World Performance of Commercial Passive Formaldehyde Removal Products: Ineffectiveness and Undisclosed VOC Emissions

Abstract

Growing public concern over indoor formaldehyde (HCHO) pollution has driven rapid growth in the use of passive HCHO removal products, which are widely marketed as low-cost and electricity-free solutions. In China, monthly sales of such products have reached millions of units. However, their real-world performance and unintended impacts on indoor air chemistry remain insufficiently characterized. Here, we evaluated the performance of five passive HCHO removal products and their volatile organic compounds (VOCs) emissions in an unoccupied office. None of the products measurably reduced HCHO concentrations under realistic conditions. In contrast, substantial VOC emissions were observed. A product claimed to be terpene-based emitted 192 μg of VOCs per gram of product consumed, with emissions dominated by aromatic compounds (50.5%), while a titanium dioxide (TiO₂)-based product emitted 155 μg g^–1 and was enriched in monoterpenoids (54.7%). Hazardous VOC signals, such as benzene, toluene, and styrene, were detected, and monoterpene emissions may have implications for indoor secondary chemistry under certain conditions. These results indicate that manufacturer-claimed HCHO removal efficiencies may substantially overestimate real-world performance and that product use can introduce additional indoor air quality concerns, highlighting the need for greater oversight and real-world testing of consumer air-cleaning products.