Levoglucosan (LG), a tracer of biomass-burning air pollution, was measured in PM10 particulate matter during a year-long study at an urban background site in Zagreb, Croatia. It is known that the atmospheric lifetime of LG is not constant and undergoes degradation through reactions with hydroxyl radicals, ozone, photooxidation, etc. In this study, daily variations in LG were examined and evaluated in relation to NO2, O3, and meteorological conditions, including temperature, relative humidity, solar irradiance, UV index, and wind characteristics. The annual mean PM10 concentration was 22 µg m−3, while LG average was 0.312 µg m−3, both exhibiting pronounced seasonal variability. Elevated LG levels occurred during winter and autumn, consistent with residential wood combustion and stable atmospheric conditions, whereas markedly lower concentrations were observed in spring and summer. Moderate correlations of LG with PM10 and NO2 indicate contributions from combustion sources, while weak wind speeds and limited dispersion favored pollutant accumulation. In contrast, significant negative relationships were found between LG and ozone, temperature, and UV index. The results revealed non-linear behavior and an exponential decrease in LG with increasing oxidant levels, suggesting pseudo–first-order degradation driven by enhanced photochemical activity and hydroxyl radical formation. These findings highlight the importance of considering both emission patterns and atmospheric processing when using levoglucosan as a tracer of biomass burning in urban environments.
Davila et al. (Thu,) studied this question.