Not a single country met the World Health Organization’s quality for air in 2021, a new study suggested. And consequently, millions are breathing polluted air that does not satisfy WHO health guidelines, according to the report that analyzed real-time air quality of 6,475 cities.

Only 222 cities have the average air quality that met WHO’s standard, according to the study conducted by IQAir, a Swiss pollution technology company that monitors air quality.

The data was collected by tens of thousands of ground-level regulatory air quality monitoring stations operated by governments, non-profit organizations, research institutions, educational facilities, companies and citizen scientists around the world.

The WHO’s standard is that average annual readings of hazardous airborne particles (PM2.5) not exceed 5 micrograms per cubic meter.

Air pollution is considered the largest environmental threat, leading to 7 million deaths per year and other respiratory problems such as asthma and lung cancer, the report stated. Exposure to PM2.5 increases both the risk of contracting COVID-19 and of suffering more severe symptoms when infected.

Bangladesh was the most polluted country, while New Delhi, India, is the world’s most polluted capital. The countries with the worst air pollution were India, Pakistan and Bangladesh, all exceeding WHO guidelines by 10 times.

Conversely, Denmark, Norway, Sweden, Australia, Canada, Japan and the United Kingdom ranked among the best countries for air quality, only exceeding the guidelines by 1 to 2 times.

Factors that have affected U.S. air pollution are wildfires and dependence on fossil fuels, according to the air quality report. In the U.S. the city with the worst pollution was Los Angeles.

Lower-income communities in the U.S. are the ones that suffer the most burdens from air pollution, the IQAir report summary stated.

“We’ve got the report, we can read it, we can internalize it and really devote ourselves to taking action,” Glory Dolphin Hammes, CEO of IQAir North America, told CNN. “There needs to be a major move toward renewable energy. We need to take drastic action in order to reverse the tide of global warming; otherwise, the impact and the train that we’re on (would be) irreversible.”

The top 10 best air quality countries or regions

1. New Caledonia

2. U.S Virgin Islands

3. Puerto Rico

4. Cape Verde

5. Saba

6. Finland

7. Grenada

8. Bahamas

9. Australia

10. Estonia

The top 10 worst air quality countries or regions

1. Bangladesh

2. Chad

3. Pakistan

4. Tajikistan

5. India

6. Oman

7. Kyrgyzstan

8. Bahrain

9. Iraq

10. Nepal

These countries have the most polluted air in the world, new report says