Which country has the cleanest air in the world?

The countries with the cleanest air in the world have been ranked in a new report. We take a look at the results

The Caribbean island of Puerto Rico has the world’s cleanest air according to the latest World Air Quality Report by IQAir. The report ranks 106 countries and territories by the level of fine particulate matter present in the air.

Air pollution continues to pose one of the biggest threats to human health, causing the death of seven million people every year. Billions more suffer the effects of poor air quality. In fact, the World Health Organisation (WHO) estimates that 92% of the global population breathes toxic air.

Puerto Rico, an unincorporated territory of the United States, has the cleanest air in the world, followed by the French territory of New Caledonia in the Pacific Ocean with the territory of the US Virgin Islands in third.

The highest-ranked sovereign states are Sweden (4th), Finland (5th), Norway (6th), Estonia (7th) and New Zealand (8th).

At the other end of the spectrum, Bangladesh has the worst air quality followed by Pakistan, India, Mongolia and Afghanistan respectively.

Songquan Deng/Shutterstock Puerto Rico has the cleanest air in the world

Air Quality Index

The report analyses results from over 60,000 monitoring stations located across the globe, making it the world’s largest centralised platform for measuring air quality.

It also draws on data collected from thousands of clean air initiatives administered by governments, non-profit organisations, citizens, communities and private companies.

The report focuses on PM2.5 concentrations as this is the pollutant widely regarded as most harmful to human health. PM2.5 is defined as ambient airborne particles measuring up to 2.5 microns in size. A micron (or micrometre) is one-millionth of a metre or one-thousandth of a millimetre.

map of the countries with the cleanest air in the world — IQAIR The countries in blue are the only ones to pass the WHO’s guidelines

Its microscopic size allows the particles to enter the bloodstream via the respiratory system and travel through the body, causing a range of health problems including asthma, lung cancer and heart disease.

Air pollution is also associated with low birth weight, increased acute respiratory infections and stroke.

The WHO’s Air Quality Guideline value for PM2.5 exposure – which has been proven to be free of health impacts – is 10µg/m³ or 10 micrograms of air pollutant per cubic meter of air.

There are only 25 countries or territories, out of the 106 assessed, which pass these guidelines.

most polluted cities

The report also produces a ranking for thousands of the world’s cities. Delhi famously hit the headlines in 2020 when the city witnessed drastically improved air quality when restrictions were introduced due to the pandemic.

However, the city soon returned to “normal” when pollution hit “emergency” levels in November 2020 and the city became enveloped in thick toxic smog.

Delhi in thick smog — Amit kg/Shutterstock Delhi is the world’s most polluted capital city

Bangladesh, China, India, and Pakistan share 49 of the 50 of the most polluted cities worldwide with nine of the 10 most polluted in India alone. Hotan in China is the world’s most polluted city while Delhi is the world’s most polluted capital.

Most polluted cities

Hotan, China
Ghaziabad, India
Bulandshahr, India
Bisrakh Jalalpur, India
Bhiwadi, India
Noida, India
Greater Noida, India
Kanpur, India
Lucknow, India
Delhi, India

Most polluted capital cities

Delhi, India
Dhaka, Bangladesh
Ulaanbaatar, Mongolia
Kabul, Afghanistan
Doha, Qatar
Bishkek, Kyrgyzstan
Sarajevo, Bosnia & Herz.
Manama, Bahrain
Jakarta, Indonesia
Kathmandu, Nepal

COUNTRY RANKING: Cleanest air in the world

The World Air Quality Report ranks 106 countries and territories. States that have been omitted lacked sufficient ground-based PM2.5 monitoring stations.