Tehran University of Medical Sciences Journal of Air Pollution and Health 2476-3071 10 2 2025 07 09 207 224 EN Maryam Malekbala Department of Environmental Health Engineering, School of Public Health, Student Research Committee, Hamadan University of Medical Sciences, Hamadan, Iran Zahra Heydari Department of Environmental Health Engineering, School of Public Health, Semnan University of Medical Sciences, Semnan, Iran Seyde Fateme Mousavi Department of Environmental Health Engineering, School of Public Health, Semnan University of Medical Sciences, Semnan, Iran. Zahra Arshian Far Department of Environmental Health Engineering, School of Public Health, Semnan University of Medical Sciences, Semnan, Iran Zeinab Khalilnezhad Department of Environmental Health Engineering, School of Public Health, Semnan University of Medical Sciences, Semnan, Iran Roohollah Rostami Department of Environmental Health Engineering, School of Public Health, Semnan University of Medical Sciences, Semnan, Iran 2024 11 11 2025 06 10 Introduction: Indoor air pollution poses significant health risks, given the substantial time individuals spend indoors. Cool-mist humidifiers have been proposed as a potential intervention for enhancing indoor air quality by influencing pollutant concentrations. This study investigates the effects of gas dissolution in vapor particles generated by a cool-mist humidifier on indoor air pollutants. Materials and methods: A controlled laboratory experiment was conducted within a 1 m³ insulated plastic chamber to monitor key parameters, including Carbon monoxide (CO), Carbon dioxide (CO₂), Oxygen (O₂), Total Volatile Organic Compounds (TVOCs), temperature, and Relative Humidity (RH). Pollutants were introduced using a lit candle and formaldehyde, and air quality was measured using a digital gas analyzer (CEM GD-3803) and a TVOC analyzer (QB2000N/T). Baseline pollutant levels without humidification were compared to levels observed with a cool-mist humidifier operating at various humidification rates (110–370 mL/h) over an 8-h period. Results: The results indicated consistent reductions in CO₂ and TVOC concentrations across all tested humidification rates, accompanied by increases in temperature and relative humidity. CO concentrations exhibited more variable behavior, with alternating increases and decreases over the testing periods. Conclusion: These findings underscore the potential of cool-mist humidifiers as an effective strategy for reducing indoor air pollutants, particularly CO₂ and TVOCs. This has meaningful implications for enhancing indoor air quality and protecting public health. https://japh.tums.ac.ir/index.php/japh/article/view/854 https://japh.tums.ac.ir/index.php/japh/article/download/854/438