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The pollution characteristics of PM2.5 and correlation analysis with meteorological parameters in Xinxiang during the Shanghai Cooperation Organization Prime Ministers’ Meeting were investigated. During the whole meeting, nine PM2.5 samples were collected at a suburban site of Xinxiang, and the average concentration of PM2.5 was 122.28 μg m−3. NO3−, NH4+, SO42− accounted for 56.8% of the total water-soluble ions. In addition, with an exception of Cl−, all of water-soluble ions decreased during the meeting. Total concentrations of crustal elements ranged from 6.53 to 185.86 μg m−3, with an average concentration of 52.51 μg m−3, which accounted for 82.5% of total elements. The concentrations of organic carbon and elemental carbon were 7.71 and 1.52 μg m−3, respectively, lower than those before and after the meeting. It is indicated that during the meeting, limiting motor vehicles is to reduce exhaust emissions, delay heating is to reduce the fossil fuel combustion, and other measures are to reduce the concentration of PM2.5. The directly dispersing by mixing layer height increase and the indirectly reducing the formation of secondary aerosol by low relative humidity, and these are the only two key removing mechanisms of PM2.5 in Xinxiang during the meeting. [ABSTRACT FROM AUTHOR]

Seventeen PM samples were collected at Xinxiang during winter in 2014. Nine water-soluble ions, 19 trace elements and eight fractions of carbonaceous species in PM were analyzed. PM concentrations and elements species during different periods with different pollution situations were compared. The threat of heavy metals in PM was assessed using incremental lifetime cancer risk. During the whole period, serious regional haze pollution persisted, and the averaged concentration of PM was 168.5 μg m, with 88.2 % of the daily samples exhibiting higher PM concentrations than the national air quality standard II. The high NO /SO ratio suggested that vehicular exhaust made an important contribution to atmospheric pollution. All of organic carbon and elemental carbon ratios in this study were above 2.0 for PM, which might reflect the combined contributions from coal combustion, motor vehicle exhaust and biomass burning. Mean 96-h backward trajectory clusters indicated that more serious air pollution occurred when air masses transported from the Hebei, Shanxi and Zhengzhou. The concentrations of the water-soluble ions and trace elements on haze days were 2 and 1.8 times of those on clear days. The heavy metals in PM might not cause non-cancerous health issues by exposure through the human respiratory system. However, lifetime cancer risks of heavy metals obviously exceeded the threshold (10) and might have a cancer risk for residents in Xinxiang. This study provided detailed composition data and comprehensive analysis of PM during the serious haze pollution period and their potential impact on human health in Xinxiang. [ABSTRACT FROM AUTHOR]

The pollution characteristics of PM 2.5 and correlation analysis with meteorological parameters in Xinxiang during the Shanghai Cooperation Organization Prime Ministers' Meeting were investigated. During the whole meeting, nine PM 2.5 samples were collected at a suburban site of Xinxiang, and the average concentration of PM 2.5 was 122.28 μg m -3 . NO 3 - , NH 4 + , SO 4 2- accounted for 56.8% of the total water-soluble ions. In addition, with an exception of Cl - , all of water-soluble ions decreased during the meeting. Total concentrations of crustal elements ranged from 6.53 to 185.86 μg m -3 , with an average concentration of 52.51 μg m -3 , which accounted for 82.5% of total elements. The concentrations of organic carbon and elemental carbon were 7.71 and 1.52 μg m -3 , respectively, lower than those before and after the meeting. It is indicated that during the meeting, limiting motor vehicles is to reduce exhaust emissions, delay heating is to reduce the fossil fuel combustion, and other measures are to reduce the concentration of PM 2.5 . The directly dispersing by mixing layer height increase and the indirectly reducing the formation of secondary aerosol by low relative humidity, and these are the only two key removing mechanisms of PM 2.5 in Xinxiang during the meeting.

Seventeen PM 2.5 samples were collected at Xinxiang during winter in 2014. Nine water-soluble ions, 19 trace elements and eight fractions of carbonaceous species in PM 2.5 were analyzed. PM 2.5 concentrations and elements species during different periods with different pollution situations were compared. The threat of heavy metals in PM 2.5 was assessed using incremental lifetime cancer risk. During the whole period, serious regional haze pollution persisted, and the averaged concentration of PM 2.5 was 168.5 μg m -3 , with 88.2 % of the daily samples exhibiting higher PM 2.5 concentrations than the national air quality standard II. The high NO 3 - /SO 4 2- ratio suggested that vehicular exhaust made an important contribution to atmospheric pollution. All of organic carbon and elemental carbon ratios in this study were above 2.0 for PM 2.5 , which might reflect the combined contributions from coal combustion, motor vehicle exhaust and biomass burning. Mean 96-h backward trajectory clusters indicated that more serious air pollution occurred when air masses transported from the Hebei, Shanxi and Zhengzhou. The concentrations of the water-soluble ions and trace elements on haze days were 2 and 1.8 times of those on clear days. The heavy metals in PM 2.5 might not cause non-cancerous health issues by exposure through the human respiratory system. However, lifetime cancer risks of heavy metals obviously exceeded the threshold (10 -6 ) and might have a cancer risk for residents in Xinxiang. This study provided detailed composition data and comprehensive analysis of PM 2.5 during the serious haze pollution period and their potential impact on human health in Xinxiang.