Tehran University of Medical Sciences Journal of Air Pollution and Health 2476-3071 10 4 2025 12 28 559 568 Rezvan Amiri Department of Environmental Health Engineering School of Public Health and Safety, Shahid Beheshti University of Medical Sciences, Tehran, Iran Abbas Shahsavani Department of Environmental Health Engineering, School of Public Health and Safety, Shahid Beheshti University of Medical Sciences, Tehran, Iran AND Air Quality and Climate Change Research Center, Research Institute for Health Sciences and Environment, Shahid Beheshti University of Medical Sciences Tehran, Iran Shahriar Bezazpour Department of Environmental Health Engineering School of Public Health and Safety, Shahid Beheshti University of Medical Sciences, Tehran, Iran Anoshivan Mohseni Bandpey Department of Environmental Health Engineering School of Public Health and Safety, Shahid Beheshti University of Medical Sciences, Tehran, Iran Seyyed Nadali Alavi Department of Environmental Health Engineering School of Public Health and Safety, Shahid Beheshti University of Medical Sciences, Tehran, Iran Mehrnoush Abtahi Department of Environmental Health Engineering School of Public Health and Safety, Shahid Beheshti University of Medical Sciences, Tehran, Iran 2025 01 08 2025 09 24 Introduction: Microplastics (MPs) pollution has become a significant global environmental concern, with various sources contributing to its spread. However, the release of MPs from healthcare waste disposal systems, which often involve shredding plastic waste, has not been widely studied. This research investigates the presence and concentration of MPs in the air surrounding autoclave and hydroclave devices at hospital waste disposal sites in Tehran. Materials and methods: A cross-sectional study was conducted from May to August 2024 in eight hospitals in Tehran, encompassing both autoclave and hydroclave systems. Air samples were collected from distances of 0,5, and 10 m from the waste management units during their operation and when they were off. A total of 48 samples were analyzed for microplastic particles using light microscopy and Raman spectroscopy to determine particle characteristics such as size, shape, and color. Results: The average concentration of MPs in the air surrounding autoclave and hydrocalve devices was 45±43 (N/m3) and higher concentrations were observed when the devices were active. No significant differences were observed between the autoclave and hydroclave systems. Microplastic particles in the air of the disinfected areas were mainly fibrous (95%) and black (70%), and the average particle length was 34.93 μm. Smaller particles, which pose more health risks, were the most common particles. Conclusion: Hospital waste disposal units, especially their shredder systems, are a significant source of airborne MPs. These emissions, especially through inhalation are a potential health risk. This study highlights the need for further research and mitigation strategies to reduce microplastic emissions in healthcare settings https://japh.tums.ac.ir/index.php/japh/article/view/883 https://japh.tums.ac.ir/index.php/japh/article/download/883/457