Quaternary ammonium compounds in house and automotive cabin air filter dust from South China: Occurrence and exposure insights

Quaternary ammonium compounds (QACs) are widely used in cleaning and disinfectant products, and their extensive use since the COVID-19 pandemic has raised increasing concerns about the potential health effects. However, exposure to QACs in different indoor environments remains insufficiently characterized. In this study, 18 QACs were determined in house dust (n = 45) and automotive cabin air filter (ACAF) dust (n = 50) from South China. The median ∑QAC concentrations were 6968 and 7982 ng/g in house and ACAF dust, respectively. Alkyltrimethylammonium compounds (ATMACs) predominated, comprising 51.5% in house dust and 65.0% in ACAF dust, with median concentrations of 3298 and 5600 ng/g, respectively. Dwelling factors did not significantly affect QAC concentrations in house dust, whereas in ACAF dust, benzyldimethyldecylammonium chloride (C10-BAC) decreased with mileage, and C10-BAC and benzyldimethyloctylammonium chloride (C8-BAC) varied with vehicle manufacturers. Toddlers exhibited higher estimated daily intakes of QAC (median: 124 ng/kg bw/day) than adults (4.02 ng/kg bw/day) under high exposure scenarios. Although the estimated health risks of QACs in this study were relatively low, ACAF dust showed comparable ∑QAC concentrations with house dust and demonstrated its value as a passive sampling matrix for assessing long-term accumulation and human exposure in vehicle environments. • Eighteen QACs were frequently detected in house and ACAF dust. • ATMACs consistently emerged as the dominant QAC group. • Environmental factors had limited impact on QAC levels in house dust. • ACAF dust levels were influenced by mileage and manufacturer. • Toddlers showed higher exposure than adults, though individual HQs were <1.