Chemical Characteristics and Public Health Risk Assessment of PM_2.5-Bound Elements in Sheohar, India

In order to measure the seasonal variations, source identification, and human health risk of elements in PM_2.5 were collected from January 2021 to December 2021 at an urban site in Sheohar, India. Element (Na, Mg, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, and Pb) concentrations were estimated using an inductively coupled plasma optical emission spectrometer (ICP-OES). The enrichment factors (EFs) and principal component analysis (PCA) were used to identify the sources of these elements, and the United States Environmental Protection Agency (US EPA) models were used to evaluate the carcinogenic and non-carcinogenic risks to both children and adults. The results showed that the annual mean concentration of PM_2.5 was 104.22 μg m⁻³ which exceeded the National Ambient Air Quality Standards (NAAQS, 40 μg m⁻³) and the World Health Organisation (WHO, 10 μg m⁻³) limits. The seasonal variation of PM_2.5 was characterised by high concentrations in winter, followed by post-monsoon, summer, and monsoon. The average annual concentrations of As, Cd, Ni, and Cr were 17.25 ng m⁻³, 32.68 ng m⁻³, 158.16 ng m⁻³, and 177.41 ng m⁻³, respectively, which were above the WHO limits. The concentrations of Ca and Fe were highest in the summer season. The concentrations of Mg and Na were highest in the monsoon season. The other element concentrations were highest in the winter season. Enrichment factor analysis showed that Zn, As, Pb, and Cd were predominantly from anthropogenic sources. In addition, source apportionment by PCA identified six components for the studied elements. The total carcinogenic and non-carcinogenic risks of elements exceeded the safe level of exposure for both children and adults, which indicate further research on sources of air pollution and measures for controlling pollutants in Sheohar, India.