Air pollution is deadly – in fact, a recent study found that on average, it cuts human lifespan by three years, which is higher than the global effect on lifespan caused by smoking. No level of pollution is safe, but the World Health Organization (WHO) has set a target of 10 micrograms per cubic metre (µg/m³) of fine particulate matter (known as PM2.5 particles), a level that it says minimises the risk of adverse health effects. However, many countries have much higher levels of PM2.5 particles, which can lead to "low birth weight, increased acute respiratory infections, and stroke".

While the coronavirus pandemic and subsequent lockdowns enforced by governments across the world have seen 84% of monitored countries report air quality improvements, including across most major cities, in some nations pollution levels are already starting to surpass what they were before the pandemic even started. As we celebrate world Earth Day (22 April), click or scroll through the 15 most and 15 least polluted countries in the world according to the 2020 World Air Quality Report produced by air pollution tracking organisation IQAir.

Air pollution in Kuwait is caused by a range of factors including vehicles, construction projects, smoke from chimneys and dust and sand storms. Kuwait City’s air had been classified as “moderate” by the Air Quality Index in 2020, which is an improvement from its “unhealthy” rating in 2019. This has been helped by vehicle traffic greatly reducing and construction having ground to a halt during the pandemic, but this has led to huge numbers of migrant workers losing their jobs. What happens next will likely depend on what path the government pursues for recovery.

 

The toxic smog that often envelops China’s cities is well-known, though it is far from the most polluted country, coming in at 14th in the 2020 IQAir rankings. Its densely populated cities might explain why the air seems so deadly – with recent research claiming that long-term exposure to air pollution killed 30.8 million people in China between 2000 and 2016. However, the coronavirus outbreak did affect pollution levels, with NASA images showing a clear reduction in nitrogen dioxide levels across the country, which it says were "at least partly" associated with the economic slowdown caused by the disease. That said China’s economy has bounced back quicker than any other, and by July 2020 levels of pollution had already risen beyond levels seen pre-pandemic, according to the Centre for Research on Energy and Clean Air, and so it's expected that the level of particles will rise again for 2021.

Mali is a landlocked country in West Africa with serious air pollution issues. The country’s PM2.5 concentration is more than three times above WHO exposure recommendations at a level of 37.9 µg/m3. Air quality in West Africa as a whole is difficult to gauge, as local monitoring systems can be unreliable, but it’s believed that the high pollution levels could lead to a 1.2 year drop in life expectancy in the area, according to a 2020 report by The Energy Policy Institute at the University of Chicago. Factors contributing to Mali’s dire air quality include old vehicles that run on fuel with a high sulphur content, open waste burning, and diesel electricity generation in lieu of a reliable central grid.

Poorer parts of southern and eastern Asia have some of the highest urban pollution, with annual levels averaging over five times the recommended limits. In Nepal, it has contributed to rising rates of lung and skin disease, according to the BBC. Even major landmarks such as Buddha’s birthplace of Lumbini have been affected by industrial activity nearby. Tourists have reported breathing issues and monks were known to wear masks even before the outbreak of COVID-19. A country-wide lockdown did unlock the beauty of areas such as the Kathmandu Valley though, according to satellite images, if only temporarily.

The presence of nearby deserts causes severe dust storms in parts of the Middle East, including the world’s eleventh most polluted country, Bahrain. They mark a stark contrast to the smog that engulfs cities in other polluted parts of the world, but the dirt and other materials caught up in the storms can still keep people inside and even prove fatal, as reported by the Middle East Eye. However, the coronavirus pandemic's impact on travel has ed to less vehicle pollution, and likely caused the drop in polluting particles in 2020 which fell from 46.8 µg/m3 in 2019 to 39.7 µg/m3.

In January 2020, the thick smog and pollution enveloping Bosnia and Herzegovina’s capital Sarajevo was so bad it prompted the Swedish embassy to brand it “in a category of its own”. Large coal power stations emit sulphur dioxide and other pollutants into the atmosphere, with 44,000 years of life expectancy lost each year due to particulate matter or nitrogen dioxide in the country, according to the UN. The government has banned diesel vehicles from Sarajevo city centre and even recommended that residents use protective masks before the pandemic. Not even the coronavirus lockdown has been able to bring down air pollution levels in this Balkan country, with pollution rising from 34.6 µg/m3 in 2019 to 40.6 µg/m3 in 2020. Satellite images from the European Space Agency have shown how the polluting power plants are having a detrimental impact on the air quality.

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The ninth most polluted country in the rankings, the Air Quality Life Index released a specific report on the impacts of air pollution in Indonesia in 2019, which states that the average Indonesian loses 1.2 years of life expectancy due to pollution. In the worst affected regions, that figure is as high as four years. Each year, pollution causes schools to temporarily close their doors because officials deem the air quality to be “dangerous”. However, photos vividly show the effect a reduction in people's movements due to the COVID-19 pandemic have had on the air quality in the capital Jakarta, and pollution levels have decreased considerably from 51.70 µg/m3 in 2019 to 40.7 µg/m3 in 2020.

Corruption is rife in the central Asian state of Kyrgyzstan, but its impact on the country’s population is eclipsed by the debilitating air quality. In 2019, Kyrgyzstan reported average PM2.5 levels of 33.2 µg/m3, which are deemed “moderate” by IQAir, but the country has bucked the global trend and witnessed air quality levels decrease to a level that is “unhealthy for sensitive groups” in 2020. The capital of Bishkek is particularly susceptible to high levels of air pollution caused by industrial growth, increases in energy production and urban development, and in November 2019 recorded several “hazardous” levels of air pollution. At these air quality levels, IQAir recommends avoiding outside activity altogether. Harsh winters exacerbate the poor air quality, as pollution-producing stoves and industrial furnaces are heavily relied upon to counter the bitter winds blowing in from Siberia.

This is the first year that the Middle Eastern country of Qatar has featured in the IQAir World Air Quality Report, although air pollution has long been an issue  there. At the beginning of 2021, Qatar’s air quality was deemed so bad that it was considered “unhealthy for sensitive groups”. Qatar has the world’s third-largest natural gas reserves – around 12.5% of the global reserve – according to the US Energy Information Administration (EIA), and it is the world’s largest exporter of liquefied natural gas, according to 2019 data. The exploration, production and manufacture of this gas is at the core of Qatar’s deteriorating air quality, and the government has reportedly said it will spare no effort in combatting air pollution, while it continues to develop the country’s most lucrative industry.

This year also marks Oman’s debut in the IQAir World Air Quality Report, and the oldest independent state in the Arab world is also the most polluted. Rapid economic development, improved living standards and denser urban populations have all contributed to a high level of air pollution in the sultanate, which currently has a PM2.5 concentration of 44.4 µg/m3. Coastal areas are some of the worst affected, as a combination of industrial concentration and unfavourable natural conditions intensifies pollution issues. Sohar City on the northern coast is a prime example of this, as is Oman’s capital Muscat, which also suffers from heightened nitrogen oxygen levels due to dense vehicle traffic, according to a 2015 report by WHO. 

In Afghanistan, people are more likely to die from air pollution than civil war. There were 26,000 deaths caused by air pollution-related diseases in 2017 compared to 3,483 deaths caused by war, according to a report by the Afghanistan Research Center. The landscape exacerbates the problem as the mountains that surround the capital, Kabul, trap polluted air and dust over the city. The poor quality of fuel used by many homes and businesses also worsens the problem, and sometimes citizens wore face masks when outside even before the pandemic. Lockdown has improved air quality, as the level of PM2.5's dropped from 58.8 µg/m3 in 2019 to 46.5 µg/m3 in 2020 according to IQAir data, but the respite may only be temporary. And sadly the respiratory problems people face are likely to make them more susceptible to coronavirus.

Few places have more polluted air in the winter than the Mongolian city of Ulaanbaatar, where 46% of the population lives and pollution can reach more than 133 times above the limits recommended by the WHO. Faced with a public health crisis, in May 2019 the government banned coal burning in the capital to reduce pollution levels. As an alternative heat source, the government encourages people to use a product made of semicoke, a by-product of coal, which burns for twice as long and gives off fewer fumes. And it seems like the pandemic year has also had a positive effect of particles in the air, dropping from the unhealthy level of 62 µg/m3 in 2019 to 46.6 µg/m3 in 2020, which is categorised as only unhealthy for sensitive groups. That said, as in Afghanistan, having been exposed to high pollution levels is likely to make more people susceptible to coronavirus due to respiratory conditions.

The air in India’s traffic-clogged capital was so bad in December 2019 that breathing it in was equivalent to smoking 50 cigarettes a day, according to USA Today. Pollution tends to get worse during winter, when the air over the city becomes cool, dry and still, meaning pollution is more easily locked in. At the same time, some residents turn to open fires for cooking and heating, which makes matters worse as it releases ash and dust. New Delhi is the most polluted capital city in the world, with an average PM2.5 concentration of 84.1 µg/m3. That said, this is a great improvement on its 2019 levels of 98.6 µg/m3, which shows the dramatic impact of the country’s strict lockdown restrictions. Overall India had an average PM2.5 concentration of 51.9 µg/m3 in 2020.

Pakistan was the second most polluted country in the world in 2020 according to IQAir, and 22% of deaths a year are caused by pollution, according to a 2015 study in the medical journal Lancet. In May 2018, the court-appointed Smog Commission implemented the Punjab Clean Air Action Plan, which recommended actions including emission-reducing technologies and the establishment of Smog Response Desks. Yet Amnesty International claims it’s not enough. “The government of Pakistan needs to do much more to adequately address such a severe public health crisis,” said Rimmel Mohydin, a campaigner. While lockdown has significantly improved air quality in Pakistan as a whole, falling from 65.8 µg/m3 in 2019 to 59 µg/m3, the level is still classed as unhealthy overall. What's more, pollution levels in the city of Islamabad have actually increased from 35.2 µg/m3 in 2019 to 39 µg/m3 in 2020, making it the eleventh most polluted capital in the world, according to IQAir.

Bangladesh had the highest levels of PM2.5 pollution in the world in 2020, at an average rate of 77.1 µg/m3. While this is a drop from 2019's levels of 83.3 µg/m3, the levels remain unhealthy for the general population. The situation is worst in the city of Dhaka, and despite lockdown it remains the second most polluted capital in the world. Pollution figures recorded in other cities by IQAir don't show significant improvement either. The government has tried introducing measures such as fining polluters and encouraging use of lower-emission brick kilns, but campaigners say it’s not enough. “The authorities have no interest in combating air pollution. They are doing nothing effective,” Abdul Matin, general secretary of Bangladesh Poribesh Andolon told the Dhaka Tribune.

Turning now to the countries with the lowest pollution levels on the 2020 IQAir list, in 15th place is the United Kingdom. Air pollution is a keenly watched issue in the UK as, despite its ranking for 2020, poor air quality is still believed to contribute towards 40,000 premature deaths each year and in April this year “toxic air” from traffic was given as a cause of death for the very first time in the case of nine-year-old Ella Kissi-Debrah, who passed away in 2013. The concentration of PM2.5s fell from 10.5 µg/m3 in 2019 to below the WHO's recommended limit of 10 µg/m3, which is likely a result of the COVID-19 pandemic restrictions. The UK government has also set ambitious targets to tackle its air pollution problem, including a ban on selling new petrol and diesel cars in the UK from 2030 and plans to increase renewable energy production through offshore wind farms and nuclear power plants. In 2018 and 2019 the cleanest air in the UK was mainly found in Scottish cities, while London is listed as the 19th least polluted capital in the world by IQAir.

Between 2019 and 2020 the air quality in Costa Rica fell below the WHO target of 10 µg/m3. That said, the central American country is far from perfect when it comes to air quality, with transport a main source of pollution in the cities. In order to improve air quality in Costa Rica, the WHO made the following recommendations: “prioritising rapid urban transit, walking and cycling networks in cities as well as rail interurban freight and passenger travel” and “shifting to cleaner heavy duty diesel vehicles and low-emissions vehicles and fuels”. 

In Quito, Ecuador's capital, the government has put into place a Transit Oriented Development (TOD) strategy which aims to maximise the amount of public space in walking distance of public transport, prioritising environmental and social sustainability and shifting away from private vehicles. The country's lockdown during the pandemic has further improved air quality, and it fell from 8.6 µg/m3 in 2019 to 7.6 µg/m3 in 2020.

Strong environmental regulations have helped maintain enviably clean air across urban Australia, although bushfires caused a rapid spike in PM2.5 air pollution last year. In Sydney, Australia’s largest city by population, the air quality exceeded “hazardous” levels at several points during the fires, leading to a 10% rise in hospital admissions. In order to address the issue, in January 2020 health authorities recommended people avoid exercising outdoors, as people breathe in more when they exercise. Early research showed a small increase in air quality during the country's lockdown, although recent research suggests that air pollution contributed to 3% of Australia’s COVID-19 deaths. 

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The tiny European country of Andorra has much better air quality than most, with an average PM2.5 concentration of 7.4 µg/m3. Situated in the Pyrenees Mountains, Andorra benefits from hydropower which helps to drive down emissions, but waste incineration plants, asphalt and concrete production, and agricultural waste burning do contribute to air pollution in the region.

Many of Canada’s cities rank among the cleanest in the world for their air quality, including major centres like Ottawa (pictured), which is the eighth best capital city in the world when it comes to clean air, Toronto and Vancouver. In Ottawa, the vast greenbelt around the city, relatively small population for a capital and successful bike-share schemes show how pollution can be curbed. Canada even has a Clean Air Day to encourage the public to reduce pollution even further. Even before the pandemic Canada had "good" levels of pollution at 7.7 µg/m3 in 2019, but fell further to 7.3 µg/m3 in 2020.

Iceland is one of the best countries in the world when it comes to air pollution levels, largely because it’s blessed with cheap and eco-friendly geothermal energy that powers much of the small nation’s heating and electricity. Contrary to the island’s clean image, not everything is rosy when it comes to the environment, however. The European Environment Agency has warned that pollution levels soar during the rush hour in winter, due to the use of sand and studded tyres on icy roads. In fact, unlike the majority of countries, Iceland has actually seen its air pollution levels increase to 7.2 µg/m3 in 2020 up from 5.5 µg/m3 in 2019, pushing it from the top three countries for air quality in 2019 to ninth place in the most recent ranking.

Strong winds sweeping in from the sea, relatively low urban populations and a lack of heavy industry ensure high air quality in New Zealand. Efforts to increase energy efficiency and improve waste systems in cities such as Wellington have also made a difference. According to the New Zealand government, the key contributors to air pollution are burning wood and coal, with home heating causing a third of PM2.5 particles. Officials suggest changing technologies, such as improved wood burners, combined with behavioural change, will be key to reducing pollution even further. IQAir data suggests the country's lockdown has led to a further small improvement in air quality.

The medieval heart of Tallinn, Estonia’s capital, probably has its narrow, cobbled streets to thank for keeping traffic levels low rather than any environmental initiative. Wind from the Gulf of Finland also stops the build-up of polluted air in the coastal city, according to the local government. Yet officials can take some credit for the city’s extensive green spaces, free public transport and a reduction in the burning of domestic waste. During the COVID-19 outbreak researchers have reported being able to see across the Gulf of Finland from Finland to Estonia, in part due to decreased pollution levels from shipping and vehicles on dry land.

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Norway’s capital city is a world leader with its sustainable public transport system, which runs entirely on renewable energy, and aims to be emission-free by 2028. Thanks to its commitments to conserving natural areas and reducing pollution, Oslo was named the European Green Capital 2019 – but it’s not stopping there, as the city plans to reduce its overall emissions by 95% by 2030 (compared to 2009). Research by the Centre for Research on Energy and Clean Air found that Norway had seen decreases in both nitrogen dioxide and particulate matter pollution during lockdown.

Finnish authorities have invested heavily in public transport, aiming to make it so efficient and comfortable that citizens see no need to have their own vehicles – Helsinki is aiming to be car-free by 2025. According to Pia Anttila of the Finnish Meteorological Institute, speaking to Finnish newspaper Yle, pollution is also low because “for a long time [the country has] been implementing environmental protections in industrial sectors”, plus Finland is located far away from large industrial areas. Finland has faced a number of coronavirus lockdowns, which have prompted huge decreases in vehicle traffic on land and sea, and saw the concentration of PM2.5 particles fall by 0.6 µg/m3.

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Stockholm was named as the first European Green Capital in 2010 and has the second cleanest air of all the world’s capitals according to the latest IQAir data. It has already curbed carbon dioxide emissions by a quarter since the 1990s and the Swedish city’s authorities hope to make it fossil fuel-free by 2040. The popularity of cycling rather than car ownership, sustained efforts to cut waste and cleaner public transport have helped Stockholm and other Swedish cities limit air pollution. Although the Swedish government didn’t impose coronavirus lockdown restrictions until January this year, the Centre for Research on Energy and Clean Air reported a decrease in particulate matter pollution as people choose to stay at home during the outbreak.

As it’s a US territory, the Virgin Islands – a tiny archipelago with a population of just over 100,000 – is part of the US Clean Air Act, which has helped to drastically improve air quality since its implementation in 1970. Despite already having very clean air, the Environmental Protection Agency (EPA) has awarded the region hundreds of thousands of dollars over the years to help the islands improve air quality even further, as they are sometimes affected by hurricanes which can release pollution into the atmosphere. President Biden’s administration also recently blocked the expansion of an oil refinery on the island of St. Croix pending a review of how it could affect air pollution in the area. That said the Virgin Islands' concentration of PM2.5's increased from 3.5 µg/m3  in 2019 to 3.7 µg/m3 last year.

New Caledonia is a collection of islands in the South Pacific that also boast excellent air quality, according to the World Air Quality Report for 2020. In 2017 the territory’s congress voted for improved air quality controls following several incidents of excessive air pollution in the capital, Noumea. The new regulations enforced limits similar to those in place in the European Union and gave businesses two years to lower their emissions. A large percentage of emissions in the city come as a result of mining, as an enormous 96.65% of the country’s exports are made up of nickel, cobalt, and ferroalloys, which are made up of a combination of metals. Despite this, New Caledonia’s air pollution levels are some of the lowest in the world.

Along with the US Virgin Islands and New Caledonia, Puerto Rico has the best air quality in the world, according to IQAir. Its cities Camuy and San German are the second and third least polluted in Latin America and the Caribbean with PM2.5 concentrations of 3.7 µg/m3, which is also the island’s overall average. The deadly Hurricane Maria that hit Puerto Rico in 2017 devastated the country’s electricity grid, which contributed to excessive levels of pollutants such as sulphur dioxide, carbon monoxide and black carbon being released into the atmosphere. The Caribbean island has since seen air quality levels settle at 3.7 µg/m3, down from 10.2 µg/m3 in 2019, bringing it well under the WHO target.

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