Global emissions of air pollutants by compound 2015-2050

Emissions of carbon monoxide (CO) amounted to 1.2 billion metric tons worldwide in 2015. However, in 2050 it is projected that emissions of this pollutant will have dropped to approximately one billion metric tons. Global emissions from the majority of the pollutants shown are expected to decline in the future, except nitrogen oxides. Nitrogen oxides  Nitrogen oxides (NOx) are a group of gases that includes nitrogen dioxide (NO2). Although global emissions of this compound are set to increase in the coming decades, they have been decreasing in certain regions. For example, NOx emissions in the U.S. have fallen considerably in the past 30 years, dropping from 25 million tons in 1990 to under nine million tons in 2019. NOx emissions in the European Union have also experienced a steady decline. This can be explained by a reduction in transport sector emissions since the introduction of three-way catalysts for motor vehicles. Health impacts  Carbon monoxide is one of the most common air pollutants and is harmful for humans in high concentrations. Leaks from appliances like gas stoves can cause CO poisoning, which is why detectors are a requirement in homes. Every year, millions of deaths attributable to air pollution occur all around the world. Some of the most harmful pollutants are PM2.5 particulate matter, and nitrogen dioxide (NO2).

一氧化碳（CO）的排放量在2015年全球范围内达到了12亿吨。然而，预计到2050年，这种污染物的排放量将降至大约10亿吨。预计全球大多数污染物的排放量在未来将会下降，但氮氧化物除外。氮氧化物（NOx）是一组包括二氧化氮（NO2）在内的气体。尽管预计在未来几十年内，该化合物的全球排放量将增加，但在某些地区的排放量却在下降。例如，美国NOx的排放量在过去30年间显著下降，从1990年的2500万吨降至2019年的不到900万吨。欧盟的NOx排放量也经历了持续的下降。这一现象可归因于自引入汽车的三元催化剂以来，交通部门的排放量有所减少。健康影响方面，一氧化碳是常见的大气污染物之一，在高浓度下对人体有害。例如，煤气灶等设备的泄漏可能导致一氧化碳中毒，这也是为什么在家中使用探测器成为必要的原因。每年，全球因空气污染导致的死亡人数数以百万计。其中，最有害的污染物包括PM2.5颗粒物和二氧化氮（NO2）。