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).