In Japan, various countermeasures have been undertaken to reduce the atmospheric concentration of fine particulate matter (PM_2.5). We evaluated the extent to which these countermeasures were effective in reducing PM_2.5 concentrations by analyzing the long-term concentration trends of the major components of PM_2.5 and their emissions in Nagoya City. PM_2.5 concentrations decreased by 53% over the 16-year period from fiscal years 2003 to 2018 in Nagoya City. Elemental carbon (EC) was the component of PM_2.5 with the greatest decrease in concentration over the 16 years, decreasing by 4.3 μg/m³, followed by SO₄²⁻ (3.0 μg/m³), organic carbon (OC) (2.0 μg/m³), NH₄⁺ (1.6 μg/m³), and NO₃⁻ (1.3 μg/m³). The decrease in EC concentration was found to be caused largely by the effect of diesel emission control. OC concentrations decreased because of the effects of volatile organic compound (VOC) emission regulations for stationary sources and reductions in VOCs emitted by vehicles and construction machinery. NO₃⁻ concentrations decreased alongside decreased contributions from vehicles, construction machinery, and stationary sources, in descending order of the magnitude of decrease. Although these findings identify some source control measures that have been effective in reducing PM_2.5, they also reveal the ineffectiveness of some recent countermeasures for various components, such as those targeting OC concentrations.

中文翻译：

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2003-2018年日本名古屋PM2.5浓度变化趋势及PM2.5对策的影响

在日本，已经采取了各种对策来降低大气中细颗粒物的浓度（PM _2.5）。通过分析名古屋市PM _2.5主要成分及其排放的长期浓度趋势，评估了这些对策在降低PM _2.5浓度方面的有效程度。名古屋市从2003财年到2018财年的16年间，PM _2.5浓度降低了53％。元素碳（EC）是PM _2.5的组成部分，在16年中浓度下降幅度最大，下降了4.3μg/ m ³，其次是SO ₄ ^2-（3.0μg/ m ³），有机碳（OC）（2.0微克/米³），NH ₄ ⁺（1.6微克/米³），和NO ₃ ^-（1.3微克/米³）。发现EC浓度的降低主要是由柴油机排放控制的作用引起的。由于挥发性有机化合物（VOC）排放法规对固定来源的影响以及车辆和建筑机械排放的VOC的减少，使得OC浓度降低。NO ₃ ^-浓度下降的同时，车辆，工程机械和固定源的贡献也下降，下降幅度按降序排列。尽管这些发现确定了可有效降低PM _2.5的某些源控制措施，但它们也揭示了针对各种成分（例如针对OC浓度的那些成分）的一些近期对策无效。