College bus commuter exposures to air pollutants in Indian city: The urban-rural transportation exposure study

• Analyzed air quality along Kavundampalayam and urban areas in Coimbatore. • PM 2.5 and PM 10 levels exceeded WHO limits. • CO 2 levels reflect traffic and industrial impacts. • Morning commutes with higher particulate levels and evening with HCHO spikes. • The need for emissions control and ongoing air quality monitoring. This study analyzes air quality along the Kavundampalayam transit route and across three urban regions in Coimbatore, India – Kavundampalayam, Ganapathy and Kovaiputhur – over five days during morning and evening commutes. Key pollutants monitored include PM 1 , PM 2.5 , PM 10 , CO 2 , formaldehyde (HCHO), and the Air Quality Index (AQI). Results show that PM 2.5 levels often exceeded the WHO's 24-hour limit, with Kovaiputhur peaking at 120.33 µg/m³ and PM 10 concentrations reaching 259.08 µg/m³ in Kavundampalayam. CO 2 levels varied significantly, with Ganapathy recording the highest at 1942.42 ppm, indicating traffic and industrial sources. Morning commutes exhibited higher PM levels due to vehicular emissions, while evenings showed reduced pollution. HCHO concentrations, though low (<0.023 mg/m³), spiked in the evenings, suggesting emission sources later in the day. A strong correlation between CO 2 and AQI underscores the impact of anthropogenic activities on air quality. The study identifies pollution hotspots using heatmaps and temporal patterns, emphasizing the need for interventions like emission control, dust regulation, and green infrastructure. Continuous air quality monitoring is essential for sustainable urban planning, helping policymakers design strategies to reduce exposure risks and improve public health.