12月18日16时，北京市实时空气质量为中度污染，首要污染物为细颗粒物（PM2.5）。本次空气污 染不仅出现在北京，我国东部地区出现了连片空气污染状况。中国环境科学研究院研究员胡京南说，14 日起，随着风力减弱，雪后近地面增湿且出现逆温，空气质量逐渐转差，京津冀及周边地区、长三角地 区北部、湖北省大部地区出现了空气污染过程，主要是PM2.5污染，目前部分地区已达到中至重度污染 水平。 今年秋冬季以来，京津冀及周边地区已出现多次空气污染过程。国家城市环境污染控制技术研究中 心研究员彭应登说，这说明我国空气质量改善还处在"爬坡"阶段，从量变到质变的拐点还没有到来。 重点行业和柴油车排放是PM2.5污染主因 本次污染过程出现的主要原因是什么？专家认为，高湿大雾、贴地逆温等不利气象条件叠加污染高 排放，导致污染物持续累积和转化，加重PM2.5污染程度。 中央气象台首席预报员安林昌说，18日，我国华北中南部、江淮西部、江汉、四川盆地等地的部分 地区出现大雾天气。北京南部、河北中南部、河南南部、安徽中部、湖北东部等部分地区出现能见度低 于500米的浓雾，局地能见度不足200米。 大气静稳、高湿状态不仅容易产生大雾，也不利 ...

18日-19日，污染向太行山前辐合汇聚，预计天津、河北中南部、山东西部和河南中北部以中至重度污 染为主。20日-22日，受东北冷空气影响，污染自北向南逐步清除；部分地区改善较晚，20日-21日污染 天气可能维持。 其中，北京市19日空气质量可能达到中度污染水平；20日起，受冷空气影响，空气质量改善至优良。 新京报讯（记者张璐）北京今天（12月18日）0时启动空气重污染黄色预警。9时，北京空气质量指数 156，为4级中度污染。 上个周末的雨雪和大风降温天气过后，我国东部地区转为弱偏南风控制；地面积雪消融导致大气增湿显 著，冀鲁豫三省交界地区有能见度不足200米的强浓雾；贴地逆温强度大，部分城市近地面到高空300米 温差达到7℃。预计18日在太行山前还将出现风场辐合，大气污染扩散条件进一步转差。 另外，污染排放处于高位，局地燃煤污染贡献不容忽视，导致污染物持续累积和转化，加重PM2.5污染 程度。以京津冀及周边地区为例，从污染排放来看，区域火电供热行业活动水平持续增长，近期开工率 较采暖季前相比已上升约20个百分点；钢铁、焦化、平板玻璃、炼油石化等行业大量不可中断工序活动 水平仍维持高位；降雪后道路交通流量和工程 ...

11月2日起，扩散条件转不利，区域污染持续积累升高。3日夜间，太行山前邯郸-石家庄-邢台-保定一 线，PM2.5达到良-轻度污染水平；4日在偏南风下，区域污染范围向北扩大并加重，4日夜间京津冀多 个城市达到轻度-中度污染水平。在此期间，北京PM2.5浓度逐渐升高，2日上午仍为个位数，至5日凌 晨上升至3级轻度污染水平。 气象条件偏不利，导致污染持续积累、传输。过程前期2-3日，区域受东部高压后部作用，地面大范围 偏南风，且出现较强的逆温，导致污染发生积累，并在南风下沿太行山向北传输。过程中期4-5日高压 系统减弱，区域进入低压系统控制，尤其是5日区域出现大雾天气，边界层低至300米，扩散条件较前期 进一步转差，高湿静稳条件下，颗粒物二次反应加强，导致PM2.5污染加重。 PM2.5组分中硝酸盐、均氯离子、有机物明显上升，区域燃烧源和二次源贡献突出。在北京PM2.5浓度 抬升期间，城区站点一二次组分浓度均同步上升，一次组分中钾离子、氯离子上升2-4倍，体现区域生 物质燃烧源影响；二次组分中硝酸盐也增加1倍，硝酸盐/硫酸盐比值上升，体现区域传输叠加二次转化 影响共同推动PM2.5持续升高。 最新预报显示，6-7日 ...

Core Viewpoint - The recent PM2.5 pollution event in the Beijing-Tianjin-Hebei region is attributed to adverse meteorological conditions and local pollution accumulation, with significant implications for air quality management and public health [1][2]. Group 1: Pollution Causes - The PM2.5 pollution process began on October 27 due to strong temperature inversion, high humidity, and southerly winds, leading to a rapid increase in PM2.5 levels from a good level to moderate pollution by the evening of October 28 [1][2]. - Autumn and winter seasons are prone to PM2.5 pollution due to stable weather conditions, low boundary layer heights, and increased humidity, which enhance secondary transformation reactions of PM2.5 [1][2]. Group 2: Pollution Characteristics - During the pollution event, multiple cities experienced heavy fog with visibility dropping below 200 meters, and relative humidity in Beijing approached saturation [2]. - The pollution was exacerbated by the transport of high-concentration pollution from southern regions, with over 70% of the PM2.5 contribution to Beijing attributed to regional transport [2]. Group 3: Mitigation Measures - In response to the pollution, cities in the region activated pollution alerts and implemented differentiated control measures as per the Air Pollution Prevention and Control Law [2]. - In Beijing, enforcement actions were taken to ensure construction sites manage dust pollution effectively, and transportation of construction waste was regulated to prevent spillage [2]. Group 4: Forecast and Recovery - A cold front is expected to arrive on October 31, bringing northerly winds that will improve visibility and air quality, restoring it to good levels by night [3].

Core Insights - The article discusses the recent increase in PM2.5 pollution in the Beijing-Tianjin-Hebei region and surrounding areas, highlighting the worsening air quality and the actions taken by local authorities to address the situation [1][2] Group 1: Pollution Causes - The primary reasons for the recent PM2.5 pollution include high regional emissions, with over 40% of PM2.5 consisting of nitrates, indicating significant contributions from industrial and diesel vehicle emissions [1] - Meteorological conditions such as stagnant air, high humidity, and temperature inversions have exacerbated the pollution levels, leading to a pattern of accumulation, brief relief, and intensification [1] - Local emissions combined with regional pollution have caused a rapid increase in PM2.5 concentrations in Beijing [1] Group 2: Response Measures - Cities in the Beijing-Tianjin-Hebei region have activated heavy pollution weather alerts based on air quality forecasts, implementing differentiated control measures [2] - As of the 28th, 17 cities in the region have legally initiated pollution alerts [2] - The China Environmental Monitoring Station predicts that air quality will improve in northern cities due to weak cold air from the northeast, while central and southern Hebei and northern Henan may still experience short-term moderate to heavy pollution [2]

Core Viewpoint - The PM2.5 pollution in the Beijing-Tianjin-Hebei region and surrounding areas has intensified since October 23, with a significant increase in pollution levels due to high emissions and adverse meteorological conditions [1][2][3]. Group 1: Pollution Trends - The region experienced a transition from "good air quality" to the first regional PM2.5 pollution event of the autumn-winter season, with PM2.5 concentrations peaking at 123 micrograms per cubic meter in Baoding on October 25 [2][5]. - The pollution spread from northern Henan to cities along the Taihang Mountains, with Baoding and Langfang reaching moderate pollution levels [2][3]. - As of October 28, the hourly PM2.5 concentration in Hebi reached 174 micrograms per cubic meter, indicating severe pollution [2][3]. Group 2: Causes of Pollution - High levels of regional pollution emissions have been maintained, with heavy-duty truck traffic increasing by 6% compared to the previous year, and 253 fire points detected in the region [3][4]. - The composition of PM2.5 during high pollution periods showed that over 40% was nitrate, indicating that industrial and diesel vehicle emissions are significant contributors [3][4]. Group 3: Meteorological Conditions - Adverse meteorological conditions, including stagnant air, high humidity, and temperature inversions, have exacerbated pollution levels, leading to a "cumulative - brief relief - intensification" pattern [4][5]. - The region experienced weak southerly winds and high relative humidity, which contributed to the accumulation of pollutants [4][5]. Group 4: Future Outlook - Air quality is expected to gradually improve starting October 30, with cities in the region implementing pollution alerts and control measures [5][6]. - The forecast indicates that from October 30 to November 2, air quality will improve to good levels due to the influence of cold air [6].