Seasonal variation in nocturnal molecular marker emissions from waste incineration in Seoul, South Korea.

Polyethylene terephthalate (PET) combustion produces terephthalic acid (TPA), a key indicator of incineration processes. This study examines the diurnal variation of TPA and its association with health risks in Seoul, South Korea, based on data from Bokjeong Station. TPA concentrations were significantly higher in winter (28.12 ng/m3) compared to summer (12.39 ng/m3), indicating increased PET-related emissions during colder months. Similarly, levoglucosan concentrations were markedly higher in winter (68.17 ng/m3) than in summer (16.67 ng/m3), likely due to waste wood incineration. The TPA-to-organic carbon (TPA/OC) ratio was notably higher at night, suggesting more frequent PET waste combustion during nighttime hours. Elevated nighttime TPA concentrations in PM2.5 also indicate contributions from coal combustion or the incineration of arsenic-containing materials. The correlation between TPA and oxidative potential underscores heightened health risks associated with nighttime emissions. Moreover, volatile organic compounds (VOCs) such as benzene, toluene, and xylene were significantly higher at night, further degrading air quality. These findings highlight the critical role of nighttime waste incineration in exacerbating urban air pollution and increasing associated health risks, especially during winter.