Spatial variability and atmospheric levels of phenolic compounds measured by passive samplers in the Strasbourg metropolitan area

Phenolic compounds are ubiquitous atmospheric pollutants mainly emitted by biomass burning, industrial activities and vehicular exhaust. In the current study, we quantified 54 phenols at six sites in the Strasbourg metropolitan area, classified into monophenols, chlorophenols, bromophenols, nitrophenols, aminophenols, and methoxyphenols. Passive samplers, consisting of nitrogen-doped carbon-coated silicon carbide foam, were deployed from 2018 to 2020 in urban, suburban and rural environments. After extraction, samples were analyzed by gas chromatography-mass spectrometry. Median concentrations ranged from < 0.5 ng m^-3 for most halogenated species to 1.6 ng m^-3 for cresols, with phenol/cresols dominating. Spatial patterns revealed diffuse urban emissions for phenol/cresols and aminophenols, whereas methoxyphenols and halophenols displayed hotspots near industrial and residential combustion sources. Inter-annual comparisons within the sampling period indicated generally stable concentrations between 2018 and 2019, except at one suburban site where levels decreased markedly, suggesting reduced biomass-burning influence. Seasonal comparisons showed no major differences between heating and non-heating periods (except at one suburban site), implying that continuous traffic and industrial emissions override heating effects. These results highlighted the predominance of diffuse urban sources and specific hotspots for phenolic pollution in Strasbourg, and provided a baseline for evaluating mitigation strategies.