Assessment of spatio-temporal patterns of fine particulate matter (PM2.5) in an urban-industrial interface in
Aishi Nath1, Ganesh Chandra Dhal2
1Department of Civil Engineering, National Institute of Technology Meghalaya, Sohra, Meghalaya, 793108, India.
Abstract:
Industrial and urban areas of Byrnihat and Guwahati experienced elevated fine particulate matter (PM2.5) concentrations over the 2023-2025 period, over the limits defined by the National Ambient Air Quality Standards (NAAQS) guideline of an annual mean of 40 μg/m3 and World Health Organization (WHO) guideline of an annual mean of 5 μg/m3. To investigate the potential geographic origins contributing to these persistent exceedances, this study applied 72-h back-trajectory analysis using NOAA's Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model alongside concentrated weighted trajectory (CWT) analysis. The framework facilitates the identification of upwind source regions contributing to receptor concentrations at Byrnihat and Guwahati. Spatial and seasonal variability, as well as associations between PM2.5 and meteorological parameters, were evaluated to characterize spatiotemporal patterns across Meghalaya and the broader Guwahati airshed. The analysis on highest concentration days in the study area revealed that air-mass origins from eastern and northwestern Indo-Gangetic Plain and along the Brahmaputra River Valley was the primary contributor during the post-monsoon and winter season. Results indicate that long-range transport episodically elevates receptor concentrations and drives pronounced spatiotemporal variability, consistent with trajectory-based source apportionment capturing air-mass pathway effects. Integrating horizontal transport direction with back-trajectory and CWT analysis improves source attribution, thereby supporting more targeted air quality management in the region.
