High levels of polycyclic aromatic compounds in outdoor and indoor PM10 of an urban residential environment during a winter pollution event in Strasbourg, France

Abstract

Polycyclic aromatic compounds (PACs) are major airborne pollutants. However, their assessment has mostly been restricted to 16 priority polycyclic aromatic hydrocarbons (PAHs). In this work, 76 PACs including PAHs, oxy-PAHs, nitro-PAHs, azaarenes, and thiaarenes were monitored in an urban residential environment. A short-term campaign was conducted at three dwellings in Strasbourg, France, with low-volume PM₁₀ samplers operated simultaneously outdoors and indoors. Household dust was also sampled in these dwellings. The PACs of interest were extracted by pressurized liquid extraction in toluene and acetonitrile, and quantified by GC-MS/MS. The total concentration of PACs in PM₁₀ was between 67 and 179 ng·m⁻³ outdoors and between 62 and 401 ng·m⁻³ indoors. Total PAC levels in settled dust varied from 3.5 to 31 μg·g⁻¹, and from 0.44 to 3.88 μg·m⁻². Due to the high influence of surfaces dust load, the interpretation of PAC concentrations in settled dust was different if mass concentrations or surface concentrations were studied. This sampling campaign concurrent with a winter pollution event led to exceptionally high concentrations of PACs. The samples of this work set maximum values for PAHs and oxy-PAHs in airborne particles among recent European studies, and an absolute maximum value for azaarenes. However, the acute short-term exposure of Strasbourg inhabitants to PACs during this pollution event is balanced by the normal concentrations of PACs in household dust, which characterizes better the long-term exposure. Source apportionment was performed thanks to PAH diagnostic ratios. It indicated a prevalence of road traffic and a possibility of PAH photochemical aging in dust.