Quantifying toxic metals contamination in air conditioning filters: implications for urban health and air quality management

Air quality is a growing concern in rapidly industrializing economies, particularly where split air conditioners (ACs) are widely used. This study aimed to assess the pollution characteristics and health risks associated with toxic pollutants trapped in split AC filter dust in an industrialized city of Pakistan. Samples of airborne particulate matter (PM), including total suspended particles (TSP), PM10, PM4, and PM2.5, were collected from busy urban intersections and analyzed. Additionally, toxic metal dust samples were gathered from AC filters installed in shops near high-traffic areas. The findings revealed that TSP, PM10, and PM2.5 levels exceeded the United States Environmental Protection Agency (US-EPA) guidelines by factors of 1.92, 2.54, and 5.38, respectively. Analysis of AC filter dust showed cadmium (Cd) concentrations exceeding World Health Organization (WHO) thresholds by a factor of 5.33. Spatial variability in pollution characteristics was noted, with contamination factor (CF), geo-accumulation index (Igeo), and ecological risk index (ERI) indicating significant heterogeneity across different sites. Both lead (Pb) and Cd were associated with non-carcinogenic health risks, with Cd posing a significant cancer risk (CR) to children, while nickel (Ni) contributed to carcinogenic risks in both children and adults. The study highlights the public health risks associated with indoor air quality degradation in high-traffic urban areas, particularly due to the accumulation of toxic pollutants in AC filters. These findings highlight the need for targeted air quality management, stricter monitoring, and mitigation measures to reduce exposure to hazardous pollutants in environments with prevalent split AC systems, thereby informing urban planning and public health strategies.