Carbonaceous composition assessment of PM2.5 near Taj Mahal in wintertime and heritage risk

Abstract

Carbonaceous components, including organic carbon (OC) and elemental carbon (EC), are critical constituents of Fine Particulate Matter (PM_2.5) as these components can significantly impact the local environment, climate, and human health. The present study aims to measure PM_2.5 and its carbonaceous content (OC and EC) in close proximity to the Taj Mahal during the winter period of January to February 2022. The estimated average mass concentration of PM_2.5 was 154.2 ± 65.4 µg/m³. This level is alarmingly high, being almost 2.5 times greater than the daily standard (60.0 µg/m³) set by the National Ambient Air Quality Standards (NAAQS) of India and a staggering 10 times higher than the World Health Organization (WHO) guidelines (15.0 µg/m³). Such elevated levels of PM_2.5 indicate severely degraded air quality in the area, posing significant risks to both the environment and human health. The concentrations of OC and EC were found to be 19.8 ± 7.8 µg/m³ and 8.11 ± 2.81 µg/m³, respectively. These value underscore the predominance of carbonaceous aerosols in the local atmosphere. OC and EC are found to be positively corelated with each other indicating their emission from similar sources. The eight carbon fraction analysis of PM_2.5 shows that biomass burning and road dust were the main sources of emission at sampling site. The average concentration of primary organic carbon (POC) was 14.67 µg/m³ whereas secondary organic carbon (SOC) was recorded as 5.55 µg/m³, highlighting that organic carbon in the region is contributed by both primary sources and secondary processes, including the condensation or adsorption of organic compounds.