Tehran University of Medical Sciences Journal of Air Pollution and Health 2476-3071 10 4 2025 12 28 525 542 Naveen Lal School of Environmental Studies, Cochin University of Science and Technology, Kochi, Kerala, India Vishnu Moorchilot School of Environmental Sciences, Mahatma Gandhi University, Kottayam, Kerala, India Charuvila Aravindakumar School of Environmental Sciences, Mahatma Gandhi University, Kottayam, Kerala, India AND Inter University Instrumentation Centre, Mahatma Gandhi University, Kottayam, Kerala, India Usha Aravind School of Environmental Studies, Cochin University of Science and Technology, Kochi, Kerala, India 2025 07 14 2025 11 29 Introduction: Research on indoor air pollution using settled dust as a medium is limited in India; therefore, this study presents the first comprehensive assessment of Total mercury (THg) in settled indoor dust across various indoor microenvironments in the Ernakulam district of Kerala state, located in southwestern India. Materials and methods: Sampling was conducted in the third week of February and the first week of March 2022 (n=32) in seven types of indoor microenvironments. Passive sampling was employed for the collection of settled dust samples, and THg in the dust samples was analysed using a Direct Mercury Analyser (Milestone DMA-80, USA). Results: The average THg concentration across all sampled environments was 0.90±0.66 mg/kg. Correlation analysis revealed a moderate (r=0.48) but statistically significant relationship (p<0.05) between THg levels and population density, likely due to contaminants brought to the indoor spaces by the people. Health risk evaluation based on hazard quotient (HQ) for ingestion and dermal exposures suggested that ingestion is the primary route of mercury exposure, with museums posing a high HQing value (0.0295) and furniture making shops posing a low HQing value (0.0001). Conclusion: This study highlights the need for mercury monitoring in urban built environments and the possible sources of mercury contamination in various indoor microenvironments. The study suggests protective measures for personal protection from dust exposure. Finally, the study concludes by suggesting the requirement for broader surveillance of mercury in various built environments in India. https://japh.tums.ac.ir/index.php/japh/article/view/1011 https://japh.tums.ac.ir/index.php/japh/article/download/1011/455