A　modeling　framework　was　proposed　to　investigate　the　impact　of　trans-boundary　air　pollutant　transport　on　regional　air　quality.　This　was　based　on　a　combination　of　the　HYSPLIT　trajectory　model,　the　CAMx　air　quality　model,　and　the　MM5　meteorological　model.　The　examination　of　atmospheric　PM10　pollution　in　Guangzhou　within　the　Pearl　River　Delta　(PRD)　region　of　southern　China　was　used　as　a　case　study.　The　HYSPLIT　and　MM5　models　were　used　to　qualitatively　identify　the　dominant　PM10　pollutant　transport　pathways　that　led　to　PM10　pollution　events　in　Guangzhou,　with　five　clusters　of　air　mass　trajectories　being　examined.　The　emission　source　contribution　through　each　transport　pathway　to　Guangzhou＇s　PM10　concentration　was　then　quantified　using　a　MM5-CAMx　modeling　system.　The　results　illustrated　that　the　trans-boundary　PM10　transport　played　a　critical　role　in　the　formation　of　PM10　pollution　events　in　Guangzhou,　with　a　mean　contribution　ratio　of　nearly　49%.　In　particular,　two　air　mass　trajectory　clusters　that　originated　from　Guangzhou＇s　surrounding　regions　were　found　to　be　the　main　pollutant　transport　pathways,　and　three　surrounding　cities　(Foshan,　Dongguan　and　Huizhou)　had　a　total　emission　contribution　of　nearly　30%　to　Guangzhou＇s　PM10　concentration　through　these　two　pathways.　The　emissions　from　these　three　cities　also　accounted　for　70　to　94%　of　the　total　trans-boundary　contributions　from　Guangzhou＇s　nine　surrounding　cities　through　the　five　transport　pathways.　As　a　result,　in　order　to　improve　Guangzhou＇s　air　quality,　coordinated　effort　is　required　to　reduce　emissions　in　both　Guangzhou　itself　and　its　three　surrounding　cities.　It　is　expected　that　the　presented　modeling　approach　can　be　applied　to　air　quality　studies　in　many　other　regions.