• Urban wetlands act as both sinks and secondary sources of airborne microplastics. • FTIR detected PE, PP, PET, PS, and PVC across air, water, soil, and plant samples. • GIS and HYSPLIT showed MPs can disperse 350 km and rise up to 1500 m altitude. • PET dominated (55%), with strong seasonal links to asthma, COPD, and bronchitis. • Positive correlation (r = 0.68, p < 0.05) between MPs and respiratory illness cases. • Findings stress urgent need for wetland restoration and integrated pollution control. This study investigated the role of Ukkadam Lake, an urban wetland in Coimbatore, India, as both a sink and secondary source of airborne microplastics, and explored their implications for respiratory health. The selection of this urban wetland was motivated by its ecological significance and increasing vulnerability to anthropogenic pollution, particularly from urban runoff. The deterioration of the site has been progressive in recent years, owing to the discharge of untreated effluents and sewage, as well as the invasive proliferation of water hyacinth. This study investigates the role of urban wetlands as both sinks and potential secondary sources of microplastics during the period 2020−2024. Special emphasis was placed on the combined impacts of microplastic pollution and fine particulate matter on respiratory health issues. The FTIR analysis detected five main types of polymers in the samples: polyethylene (38.5%), polypropylene (27.3%), PET (19.6%), polystyrene (9.4%), and PVC (5.2%). Among these, PET was the most common in aquatic plants, revealing the bioaccumulation of microplastics in the vegetation. GIS mapping showed that pollution hotspots were mainly found near urban–wetland boundaries. Dispersion modeling (HYSPLIT) indicated that airborne microplastics can rise up to 1500 m and travel more than 350 km. Seasonal weather patterns and prevailing winds strongly influence their movement. In summary, the results revealed a significant association between airborne microplastic exposure and respiratory health risks in the local population. These suggested the urgent need for targeted mitigation strategies, including the restoration and active management of urban wetlands, enhanced regulation of point and non-point pollution sources, and the development of integrated monitoring frameworks to support sustainable urban ecological management and public health protection.