Unveiling the hidden threat: A multi-faceted assessment of heavy metal contamination in indoor dust along with ecological risk and human health implications

• 11 HMs (As, Cd, Co, Cu, Cr, Fe, Hg, Mn, Ni, Pb, Se) are detected in indoor dust. • HMs distribution was residential > institutional > industrial > commercial area. • Non-carcinogenic risk for Cr is in the untenable stage. • Inhalation and ingestion are the main exposure routes. • As, Cr, Cd, and Cu pose carcinogenic risks. • Ecological risk in different indexes indicates different levels of exposure risk. Indoor environment is considered to be a sanctuary from external pollutants. But nowadays, this idea has been changed. Heavy metals (HMs) contamination in indoor dust poses a significant threat to ecological and human health. This study had been conducted in four types of indoor environments: residential, institutional, industrial, and commercial. Dust sample was collected from the AC filter. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to analyze those samples and identified 11 types of HMs (As, Cd, Co, Cu, Cr, Fe, Hg, Mn, Ni, Pb, Se, and Zn) in AC dust. Among the HMs, Fe (717.41 ± 19.04 mg/kg) was the most abundant, and Cd (2.53 ± 0.35 mg/kg) was the least abundant. Principal component analysis was carried out to understand the pattern of metals by area. It was found that As, Se, and Cr was the most abundant group among the study area. Carcenogenic and Non carcinogenic risk was also assessed for this HMs. While ingestion was the main exposure route for non-carcinogenic risk and inhalation was for carcinogenic risk. As, Cr, Cd, and Cu pose carcinogenic threats higher than safe values except Pb. Both non-carcinogenic risk and carcinogenic risk for Cr were in the unacceptable range for adults. Additionally, some indices that this study evaluated indicate a variation in risk due to the presence of HMs. This study first time identified the Hg in every sample of dust and introduced us about that hidden threat. These results also shed the light on the critical interplay between indoor contaminants and public health, urging stronger laws and increased public awareness to protect vulnerable groups.