Over a span of 34 years (1987–2019), an in-depth analysis of PM10, SO2, and NO2 trends across India was conducted using data from the National Ambient Air Quality Monitoring Programme’s manual monitoring stations in 336 cities. The study encompassed six geographical regions over three time blocks, revealing a correlation between the expansion of monitoring networks and the nation’s economic growth. Regions like the densely populated Indo-Gangetic Plains (IGP) and Central India consistently hosted more monitoring stations, while the Himalayan and Northeast regions saw substantial increases from initial scarcity. SO2 concentrations showed a declining trend, while NO2 levels remained relatively stable with intermittent fluctuations. Conversely, national average PM10 concentrations exhibited an upward trajectory, notably spiking by 128 % between 2006 and 2009 due to economic activities, construction, network expansion, the 2009 drought, and heightened coal consumption. Spatially, pollutant concentrations across three blocks demonstrated improved SO2 levels, several cities exceeding NO2 standards, and persistently high PM10 levels in the IGP. PM10 levels in block 3 were lower than in block 2, reflecting effective policy interventions. State rankings, however, did not consistently reflect pollutant trends across blocks. Regionally, the IGP consistently had the highest PM10 concentrations, while the Northeast recorded the lowest. Population-weighted exposure levels indicated an overall increase in public exposure to PM10. Analysis of major city per region aligned with national trends, as evidenced by Delhi (IGP), Guwahati (Northeast), Vadodara (Northwest), and Bhopal (Central) showing increased PM10 concentrations since 2006, followed by intermittent declines. In contrast, Shimla (Himalayan) and Chennai (Southern) exhibited distinct patterns. Major industrial cities such as Parwanoo, Bongaigaon, Angul and Talcher, and Visakhapatnam mirrored national trends, with PM10 levels rising since 2009, highlighting the significant impact of industrial activities on air quality. This research underscores the need for targeted, effective mitigation strategies based on spatial and temporal pollutant trends.

中文翻译：

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绘制印度 336 个城市的空气质量趋势图：三十年监测的见解（1987 年至 2019 年）


在 34 年（1987 年至 2019 年）的时间里，利用国家环境空气质量监测计划在 336 个城市的手动监测站的数据，对印度各地的 PM10、SO2 和 NO2 趋势进行了深入分析。该研究涵盖三个时间段的六个地理区域，揭示了监测网络的扩张与国家经济增长之间的相关性。人口稠密的印度恒河平原（IGP）和印度中部等地区持续设立了更多的监测站，而喜马拉雅山和东北部地区的监测站数量较最初的稀缺性大幅增加。 SO2浓度呈现下降趋势，而NO2浓度则保持相对稳定，并出现间歇性波动。相反，由于经济活动、建设、管网扩建、2009 年干旱和煤炭消耗增加，全国平均 PM10 浓度呈上升趋势，2006 年至 2009 年期间显着飙升 128%。从空间上看，三个街区的污染物浓度显示出二氧化硫水平有所改善，多个城市超过了二氧化氮标准，并且IGP的PM10水平持续较高。 3区PM10水平低于2区，反映出政策干预有效。然而，各州的排名并没有一致地反映各街区的污染物趋势。从地区来看，IGP 的 PM10 浓度始终最高，而东北部的浓度最低。人口加权暴露水平表明公众对 PM10 的暴露总体有所增加。对每个地区主要城市的分析与国家趋势一致，德里 (IGP)、古瓦哈提（东北部）、巴罗达（西北）和博帕尔（中部）证明 PM10 浓度自 2006 年以来有所增加，随后出现间歇性下降。 相比之下，西姆拉（喜马拉雅山）和钦奈（南部）表现出不同的模式。帕尔瓦努、邦盖冈、安古尔和塔尔切尔以及维沙卡帕特南等主要工业城市反映了全国趋势，PM10 水平自 2009 年以来不断上升，凸显了工业活动对空气质量的重大影响。这项研究强调需要根据时空污染物趋势制定有针对性的有效缓解策略。