Mobile high-resolution BTEX monitoring and seasonal cumulative health risks from BTEX and PM2.5-metals in a petrochemical complex

This study evaluated multi-pollutant exposure and health risks of benzene, toluene, ethylbenzene and xylene (BTEX) and PM2.5-bound heavy metals in the Ulsan Mipo National Industrial Complex, one of Korea’s largest petrochemical zones. Real-time BTEX concentrations were measured using a Me-DOAS system, while PM2.5 chemical components were simultaneously analyzed to assess both acute and chronic exposures. Ethylbenzene (31.28 ± 29.39 µg/m3) and m-xylene (35.39 ± 37.21 µg/m3) were dominant among BTEX, showing concentrations 5–10 times higher than those reported in other industrial regions. Diurnal and seasonal variations were significant, with BTEX peaking in winter and nighttime, whereas PM2.5 and metallic constituents (Mn, Co, Cd, V) peaked in spring. Probabilistic exposure assessment revealed that HQ values for all pollutants were generally below 1.0, indicating negligible non-cancer risks. However, short-term evening and nighttime peaks led to higher HQ for benzene and p-xylene, occasionally approaching the threshold. Time-resolved cancer risk analysis showed nighttime benzene exposure dominated total carcinogenic risk (median ECR: 3.4E-07–5.5E-07; exceedance ≤ 8.3%). These results highlight the importance of temporal variability in exposure assessment and support the use of high-resolution monitoring for time-sensitive health risk management in industrial environments.