evidence: Nitrogen dioxide (NO2) is a pollutant generated mainly through the burning of fuels in vehicles, power plants, and industrial facilities. [...] In contrast to PM2.5, some of the highest levels of NO2 pollution are seen in high-income countries. The highest exposures to NO2 are seen in North Africa and the Middle East (26.8 μg/m3), high-income countries (26.6 μg/m3), and in Central and Eastern Europe and Central Asia (26.1 μg/m3). 42% of the world’s population being exposed to NO2 levels above the annual guideline value recommended by WHO. Seven of the ten countries with the highest NO2 exposures are in the Middle East including Bahrain, Qatar, Kuwait, Lebanon, and the United Arab Emirates. Russia and Turkey also experience high NO2 levels. High-income countries are experiencing a rapid decline in NO2 exposures over time as a result of sustained policy action and technological advancements.