京津冀及周边地区秋冬季PM2.5爆发式增长成因与应急管控对策

京津冀及周边地区秋冬季大气重污染过程频发，而在一些污染过程中PM_2.5会呈现爆发式增长特征，受到社会、公众的广泛关注，但现阶段针对PM_2.5爆发式增长的成因仍缺乏系统性的认知.对京津冀及周边地区在2015-2019年秋冬季（10月-翌年3月）大气重污染过程进行整理分析，并以2016年12月16-22日和2019年1月10-14日两次典型重污染过程中的PM_2.5爆发式增长为典型案例进行成因解析，归纳得出PM_2.5爆发式增长的主要原因为本地积累、区域传输和二次转化.对于北京市，PM_2.5爆发式增长通常不是上述某一原因独立导致，而是三者综合作用的结果.对于主要由本地积累引起的PM_2.5爆发式增长，应提前采取预警应急措施，降低ρ（PM_2.5）峰值；对于主要由区域传输引起的PM_2.5爆发式增长，应开展区域应急联动，降低传输通道沿线城市对ρ（PM_2.5）累积的贡献；对于主要由二次转化引起的PM_2.5爆发式增长，应通过一次颗粒物和SO₂、NO_x、VOCs等气态污染物的协同减排，降低高湿条件下污染物二次转化的影响.在2016年12月16-22日的大气重污染过程期间，京津冀及周边地区通过采取上述应急管控对策，减少了主要污染物排放量，有效降低了ρ（PM_2.5）峰值.建议可根据各地PM_2.5爆发式增长的具体成因，通过提前采取重污染天气预警应急措施、区域应急联动和多污染物（一次颗粒物、SO₂、NO_x、挥发性有机物等）协同减排等应急管控对策，有效减少PM_2.5爆发式增长的次数、降低PM_2.5爆发式增长的速率，减缓大气重污染的发生和发展. 

Explosive Growth of PM2.5 during the Autumn and Winter Seasons in the Jing-Jin-Ji and Surrounding Area and Its Control Measures with Emergency Response

Heavy pollution episodes often occur in autumn and winter in the Jing-Jin-Ji and surrounding area in China, and some come along with PM_2.5 explosive growth, which has aroused widespread concern. Currently, a systematic recognition of the causes for PM_2.5 explosive growth is still lacking. Based on the analysis of heavy pollution episodes during the autumn and winter seasons (October to next March) of 2015-2019 and typical PM_2.5 explosive growth phenomena occurred during two typical heavy pollution episodes in this region (Dec. 16th-22nd, 2016 and Jan. 10th-14th, 2019), the PM_2.5 explosive growth is attributed to three main causes:local accumulation, regional transport and secondary formation. The PM_2.5 explosive growth in Beijing City is usually a comprehensive result of multiple causes instead of a single-cause dominated. For the PM_2.5 explosive growth mainly controlled by local accumulation, early heavy-air pollution warning should be released and emergency response measures should be adopted to reduce the maximum ρ(PM_2.5). For the PM_2.5 explosive growth mainly controlled by regional transport, regional emergency response should be taken to decrease the contribution of cities along the air-pollution transport pathways to ρ(PM_2.5). For the PM_2.5 explosive growth mainly controlled by secondary formation, joint-control measures of multiple pollutants, including primary PM_2.5, SO₂, NO_x and volatile organic compounds, should be taken out to alleviate the influence of secondary formation. In summary, based on the specific condition of PM_2.5 pollution causes in each city, it is suggested to release early warning and adopt emergency response measures, strengthen regional joint response and control the emissions of multiple pollutants, including primary particulate matter, SO₂, NO_x and volatile organic compounds, to control the frequency and magnitude of PM_2.5 explosive growth.