Annual mean concentration of NO2, PM10, and PM2.5 in metropolitan cities Italy 2022

The WHO air quality guidelines for nitrogen dioxide (NO2) and particulate matter (PM10 and PM2.5) were not followed in any of the 14 metropolitan Italian cities investigated by a recent study on air pollution. The most polluted cities were Milan and Turin, where NO2 and PM2.5 concentrations were as high as over three and four times the recommended WHO values, respectively. What are the sources of air pollution? Rome, Milan, Naples, and Turin are the largest cities in Italy. In such densely populated urban areas, fossil fuels combustion by road traffic, energy distribution, and industries are the main sources of NO2. A relevant share of PM10 is emitted by domestic heating systems, agriculture, and road vehicles, while PM2.5 is mainly of secondary origin. They are the result of chemical reactions in the atmosphere involving fossil fuels and biomass burning, nitrate and sulfate compounds, and biogenic particles. Air pollution and health The WHO air quality guidelines give recommendations regarding the annual mean concentrations of air pollutants that should not be exceeded to protect public health. The effects of short- and long-term exposure to elevated concentrations of NO2, PM10, and PM2.5 range from dizziness, headache, and irritation of the nose and throat to chronic pulmonary and cardiovascular diseases. PM2.5 can penetrate deeply into the respiratory system because of its small size (its diameter is smaller than 2.5 micrometers) and is responsible for around 50,000 premature deaths in Italy every year.

近期一项关于空气污染的研究对意大利14个都市地区的空气质量进行了调查，发现这些城市均未遵循世界卫生组织（WHO）对二氧化氮（NO2）和颗粒物（PM10和PM2.5）的空气质量指南。污染最为严重的城市为米兰和都灵，其中二氧化氮和PM2.5的浓度分别高达世界卫生组织推荐值的3倍以上和4倍。空气污染的来源包括意大利最大城市罗马、米兰、那不勒斯和都灵等地的道路交通、能源分配及工业燃烧化石燃料，其中PM10的排放量与家用供暖系统、农业及道路车辆有关，而PM2.5则主要源自二次污染。这些二次污染物是大气中化石燃料燃烧、生物质燃烧、硝酸盐和硫酸盐化合物以及生物颗粒物发生化学反应的结果。空气污染与健康方面，WHO空气质量指南提供了关于空气污染物年浓度平均值不应超过的建议，以保护公众健康。长时间或短时间暴露于NO2、PM10和PM2.5高浓度中，其影响从头晕、头痛、鼻腔和喉咙刺激到慢性肺部和心血管疾病。由于PM2.5粒径小（直径小于2.5微米），能够深入呼吸道，每年导致意大利约5万人过早死亡。