• • Construction dust and road dust are the dominant local sources of PM2.5 at the Tongzhou Dongguan site, with contributions significantly exceeding other sources, underscoring the need for targeted dust control measures.
• • Meteorological conditions, specifically low boundary layer height, weak winds, and high humidity, are closely correlated with abnormal PM2.5 increases, indicating that pollution episodes are exacerbated under stagnant atmospheric conditions.
• • The integrated tracing method, combining qualitative fingerprint analysis and quantitative modeling, successfully identified local source contributions, providing a replicable framework for county-town scale air quality management.
• • Backward trajectory analysis revealed that catering sources from the west and southwest directions significantly contributed to PM2.5 episodes, highlighting the importance of regional transport and local emission interactions.