2023 World Air Quality Report released

The 2023 World Air Quality Report was released by IQAir in March 2024. The Report provides a global review of air quality data for the year 2023. The report summarizes PM2.5 air quality data from 7,812 cities spanning 134 countries, regions, and territories. The data utilized to create this report was aggregated from more than 30,000 air quality monitoring stations operated by research institutions, governmental bodies, universities and educational facilities, non-profit organizations, private companies, and citizen scientists.

PM2.5 data is reported in units of micrograms per cubic meter (μg/m3) and incorporates the latest World Health Organization (WHO) annual PM2.5 guideline and interim targets for data visualization and risk communication (released in 2021).

Causing an estimated one in every nine deaths worldwide, air pollution is the greatest environmental threat to human health. According to WHO, air pollution is responsible for an estimated seven million premature deaths worldwide every year. Exposure to PM2.5 air pollution leads to and exacerbates numerous health conditions, including but not limited to asthma, cancer, stroke, and lung disease.2 Additionally, exposure to elevated levels of fine particles can impair cognitive development in children, lead to mental health issues, and complicate existing illnesses including diabetes.

While PM2.5 poses direct health risks, its implications extend beyond human health to complex environmental processes impacted by the Earth’s climate. Climate change, primarily driven by greenhouse gas emissions, plays a pivotal role in influencing concentrations of PM2.5 air pollutants, and fossil fuel emissions are simultaneously responsible for the majority of PM2.5 related deaths. Simultaneously addressing air pollution and climate change goals is feasible, offering opportunities for comprehensive environmental improvements.

Key findings from the 2023 World Air Quality Report:

• Seven countries met the WHO annual PM2.5 guideline (annual average of 5 µg/m3 or less): Australia, Estonia, Finland, Grenada, Iceland, Mauritius, and New Zealand.

• The top five most polluted countries in 2023 were:

o Bangladesh (79.9 µg/m3) more than 15 times higher than the WHO PM2.5 annual guideline

o Pakistan (73.7 µg/m3) more than 14 times higher than the WHO PM2.5 annual guideline

o India (54.4 µg/m3) more than 10 times higher than the WHO PM2.5 annual guideline

o Tajikistan (49.0 µg/m3) more than 9 times higher than the WHO PM2.5 annual guideline

o Burkina Faso (46.6 µg/m3) more than 9 times higher than the WHO PM2.5 annual guideline

• A total of 124 (92.5%) out of 134 countries and regions exceeded the WHO annual PM2.5 guideline value of 5 µg/m3.

• Africa remains the most underrepresented continent, with a third of the population still lacking access to air quality data.

• Climate conditions and transboundary haze were major factors in Southeast Asia, where PM2.5 concentrations rose in nearly every country.

• The region of Central & South Asia was home to the top ten most polluted cities in the world.

• Begusarai, India was the most polluted metropolitan area of 2023. India was home to the four most polluted cities in the world.

• The most polluted major U.S. city was Columbus, Ohio. Beloit, Wisconsin was the most polluted city in the U.S.

• Las Vegas, Nevada was the cleanest major city in the U.S.

• For the first time in the history of this report, Canada was the most polluted country in Northern America, with the region's 13 most polluted cities located within its borders.

• 70% of the real-time air quality data in the region of Latin America & Caribbean comes from low-cost sensors.

The following tables are based on population weighted, 2023 average PM2.5 concentration (μg/m³) for countries, regions, and territories.

        10 Most Polluted Countries

Rank Country

1 Bangladesh

2 Pakistan

3 India

4 Tajikistan

5 Burkina Faso

6 Iraq

7 United Arab Emirates

8 Nepal

9 Egypt

10 Dem. Rep. of the Congo

        10 Least Polluted Countries

Rank Country 

125 Finland

126 Estonia

127 Puerto Rico

128 Australia

129 New Zealand

130 Bermuda

131 Grenada

132 Iceland

133 Mauritius

134 French Polynesia

       10 Most Polluted Capitals

Rank & Capital Country

1. New Delhi India 

2. Dakha Bangladesh 

3. Ouagadougou Burkina Faso 

4. Dushanbe    Tajikistan

5. Baghdad Iraq 

6. Abuja Nigeria 

7. Jakarta Indonesia 

8. Hanoi Vietnam

9. Islamabad Pakistan 

10. Cairo Egypt

Thus, India has the following dubious distinctions:

• India is the third most polluted country after Bangladesh and Pakistan.

• New Delhi is the most polluted capital city of the world.

• Among the major most polluted cities, Delhi, Kolkata, and Mumbai are ranked 3, 4, and 5 respectively.

• Out of 7812 cities covered, Begusarai in Bihar is the most polluted one.

• Of the top 50 most polluted cities of the world, 42 are in India.