New Delhi is the world’s most polluted capital city for the fourth consecutive year, even as the 2021 World Air Quality Report finds that only three percent of cities and no single country met the latest World Health Organization’s (WHO) PM2.5 annual air quality guidelines. Dhaka (Bangladesh). N’Djamena (Chad), Dushanbe (Tajikistan) and Muscat (Oman) follows New Delhi.
The report analyzes PM2.5 air pollution measurements from air monitoring stations in 6,475 cities in 117 countries, regions and territories. IQAir’s 2021 World Air Quality Report is the first major global air quality report based on the updated annual WHO air quality guideline for PM2.5. The new guideline was released in September 2021 and cut the existing annual PM2.5 guideline value from 10wa/m .
KEY FINDINGS
- No country met the latest WHO air quality guideline for PM2.5 in 2021.
- Only 222 out of 6,475 global cities covered in the report met updated WHO PM2.5 guidelines.
- 93 cities in the report had annual PM2.5 concentrations exceeding 10 times the WHO PM2.5 guidelines.
- Of 174 Latin America and the Caribbean cities, only 12 (7 percent) met the WHO PM2.5 guidelines.
- Of 65 African cities, only one (1.5 percent) met updated annual WHO PM2.5 guidelines.
- Of 1.887 Asian cities, only four (0.2 percent) met updated WHO PM2.5 guidelines.
- Of the 1588 cities in Europe, only 55 (3 percent) met the WHO PM2.5 guidelines.
- The report covered 2,408 cities in the United States and found that average PM2.5 concentrations rose from 9.6 ug/m3 to 10.3 ug/m3 in 2021 compared to 2020.
- Of the major cities in the United States, Los Angeles was the most polluted. However, the City of Angels saw an overall decrease in PM2.5 pollution of 6 percent compared to 2020.
- The top five most polluted countries in 2021 were:
Bangladesh
Chad
Pakistan
Tajikistan
India
- New Delhi (India) is the world’s most polluted capital city for the fourth consecutive year followed by Dhaka (Bangladesh), N’Djamena (Chad)). Dushanbe (Tajikistan and Muscat (Oman).
- Air quality in China continued to improve in 2021. More than half of the cities in China included in the report saw lower levels of air pollution when compared to the previous year.
- Pollution levels within the capital city of Beijing continued a five-year trend of improved air quality, driven by emission control and reduction of coal power plant activity and other high emission industries.
- Central and South Asia had some of the world’s worst air quality in 2021 and was home to 46 of the world’s 50 most polluted cities. The only two cities that met updated WHO PM2.5 guideline were Zhezgazghan and Chy (Kazakhstan).
- Air quality monitoring remains sparse in Africa, South America and the Middle East, although progress has been made by low-cost air quality sensors often operated by non-profit organizations and citizen scientists.
Meanwhile, TQAir CEO Frank Hammes said, “This report underscores just how much work remains to be done to ensure that everyone has safe, clean and healthy air to breathe. The time for action is now.”
WHY PM2.52
PM2.5, particulate matter consisting of fine aerosol particles measuring 2.5 microns or smaller in diameter, is one of six routinely measured criteria air pollutants and is commonly accepted as the most harmful to human health due to its prevalence in the environment and broad range of health effects. PM2.5 is generated from many sources and can vary in chemical composition and physical characteristics. Common chemical constituents of PM2.5 include sulfates, nitrates, black carbon and ammonium. The most common human-made sources include internal combustion engines, power generation, industrial processes, agricultural processes, construction, and residential wood and coal burning. The most common natural sources for PM2.5 are dust storms, sandstorms, and wildfires.