Levoglucosan and Its Isomers as Markers and Biomarkers of Exposure to Wood Burning.

Levoglucosan and its isomers, mannosan and galactosan, are widely used atmospheric tracers of biomass combustion, and levoglucosan has been previously proposed as a potential biomarker of wood smoke exposure. This study evaluated their applicability under real-world conditions. During 14-day monitoring campaigns in both heating and non-heating seasons, daily PM_2.5 and paired urine samples were collected from adults and children in two Hungarian settlements with different heating practices. Monosaccharide anhydrides in PM_2.5 and urine were quantified by gas chromatography-mass spectrometry, while demographic, dietary, and lifestyle data were obtained via questionnaires. Ambient concentrations were substantially higher during the heating season and at the rural site, confirming the significant contribution of residential wood burning to air pollution. While urinary levoglucosan was quantifiable in >90% of samples, its isomers were often below the limit of quantification. Urinary levoglucosan concentrations did not exhibit consistent seasonal or spatial patterns and were not associated with ambient levels. Instead, an unexplained background more likely influenced by certain demographic, dietary, and behavioral factors than by environmental exposure appeared to drive urinary levels. These findings suggest that urinary levoglucosan is not a suitable biomarker for assessing residential wood smoke exposure, with similar conclusions drawn for mannosan and galactosan.