NO2 exposure levels (left) and deaths attributable to NO2 (right) in cities with a population of 50,000 or more in 2020. NO2 levels are high in cities across all regions and income levels, while death rates are highest in Asia and Eastern Europe.

Population-weighted annual average pollutant concentrations and associated health burden in cities, in 2020.

About NO2

Nitrogen dioxide (NO2) is a pollutant generated mainly through the burning of fuels in vehicles, power plants, and industrial facilities.

As a major component of vehicle exhaust, NO2 is often used as a proxy for tracking traffic-related air pollution and related health effects. NO2 and other nitrogen oxides also contribute to the formation of other harmful pollutants like ozone and PM2.5.  

NO2 irritates the airways. It is linked with more frequent and severe asthma symptoms and may increase a child’s likelihood of developing asthma. NO2 exposure may also impair lung development in children, intensify allergies, and make people more susceptible to respiratory infections.


Woman wearing mask


Why it Matters

In 2021, exposure to NO2 was linked to 177,000 DALYs, or 177,000 healthy years of life lost for children and adolescents.

People who live, work, or go to school closer to roadways often experience the heaviest traffic pollution exposure. People with asthma or other health problems that are caused or exacerbated by NO2 pollution can get sick more often, require more health care, and miss work, school, or family obligations. This creates a burden on the affected individuals as well as their families and, more broadly, society and the economy.

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.

women riding bikes


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. 

Many cities have implemented measures to reduce traffic- related air pollution. For instance, London’s Ultra Low Emission Zone initiative delivered a 36% reduction in NO2 in the first six months after its launch in 2019. Traffic measures like this have yielded air quality improvements in other cities as well.