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Haze exerts a large effect on visibility reduction and has serious impacts on air quality and human health. Understanding the sources and transport of haze is of importance to improve the regional air quality and evaluate its health effects. In this study, we investigated a typical haze episode that occurred in northeast (NE) China during 4-6 November, 2010 by analyzing the ground PM10 measurements from 11 monitoring sites, aerosol Lidar observations, synoptic charts, MODIS satellite imageries, and back trajectories. Our analyses suggest that the regional haze formed in North China Plain (NCP) under stagnant conditions can be transported to NE China in ~1-3 days across Bohai Bay and Liaodong Bay - a typical transport pathway associated with the topography of northern China. The haze episode appeared to evolve progressively from southwest to northeast in the region of NE China, in agreement with the appearance of PM10 peak values, wind patterns, MODIS images and the back trajectories of air masses. Due to the haze impact, the NE China showed significantly elevated particulate matter pollution by a factor of ~4-6 with the peak concentrations reaching ~410 μg m-3. An online air pollutant tagged module has been developed in the Nested Air Quality Prediction Model System (NAQPMS) to investigate the impact of the regional transport on the air pollutants in NE China. Analysis indicated that the BeiJing-Tianjin-HeBei (BTH) sources were important contributions at 300 m, accounting for 45% of PM10 concentration to Yingkow (YK), 36% to LiaoYang (LY), 24% to TieLing (TK) and 22% to JiLin (JL), respectively. On the episode day of 4 Nov. , there was a significant contribution (about 73 %) from BTH to YK. The results together indicate that the regional transport from the NCP has a significant contribution to the PM pollution in NE China, thus efforts to control the source emissions over NCP would be effective to improve the air quality in NE China.