Nitrogen oxide emissions in the European Union 1990-2021, by sector
Nitrogen oxide emissions in the European Union have fallen significantly across several sectors over the past few decades. In 1990, the transportation sector emitted 6.9 million metric tons of NOx, but by 2021 this figure had fallen to roughly 2.4 million metric tons. Neverthless, transportation remains the biggest contributor to nitrogen oxide emissions in the EU by far. NOx are a group of gases composed of nitrogen and oxygen, which include nitrogen dioxide.