Most polluted capital cities based on PM2.5 concentration globally 2023

New Delhi was the most polluted capital city in the world in 2023, with an average PM2.5 concentration of nearly 93 micrograms per cubic meter of air (μg/m³). PM2.5 particulate matter concentrations in the Indian capital were over nine times higher than the World Health Organizations PM2.5 target of 10 μg/m³. Despite having such high PM2.5 levels, New Delhi isn't the most polluted city worldwide. Sources of PM2.5PM2. 5 refers to atmospheric particulate matter that have a diameter of less than 2.5 micrometers. There are many sources of PM2.5 emissions, including road transport, industrial activities, crop burning, and energy industries. Domestic combustion, such as burning wood for fuel, is also a major source of PM2.5 emissions. As a result, PM2.5 concentrations are typically higher in developing countries. In comparison, PM2.5 levels in European capitals are considerably lower. Health impacts of air pollutionExposure to levels of PM2.5 ranging from 55.5 to 150.4 μg/m³ is considered unhealthy, increasing the likelihood of heart and lung problems. Air pollution is one of the leading causes of premature deaths worldwide, cutting millions of lives short every year. While this is especially the case in Asia, the impacts of these pollutants are felt everywhere. Globally, nearly 2.8 billion people were exposed to hazardous levels of air pollution in 2022.

2023年，新德里成为全球污染最严重的首都城市，其空气中PM2.5的平均浓度为约93微克每立方米（μg/m³）。印度首都的PM2.5颗粒物浓度超过了世界卫生组织设定的10 μg/m³的PM2.5目标值的九倍以上。尽管PM2.5水平如此之高，新德里并非全球污染最严重的城市。PM2.5（大气颗粒物直径小于2.5微米）的排放源众多，包括道路交通、工业活动、农作物焚烧和能源产业。家庭燃烧，如燃烧木材作为燃料，也是PM2.5排放的重要来源。因此，在发展中国家，PM2.5的浓度通常较高。相比之下，欧洲首都的PM2.5水平则相对较低。空气污染的健康影响：暴露于55.5至150.4 μg/m³的PM2.5水平被认为是不健康的，这会增加患心脏和肺部疾病的风险。空气污染是全球导致过早死亡的主要原因之一，每年缩短数百万人的寿命。尽管这种情况在亚洲尤为严重，但这些污染物的危害在全球范围内均有感受。到2022年，全球近28亿人暴露于有害的空气污染水平之中。