The USA and China are responsible for more than 40% of all the world’s CO2 emissions and with emissions continuing to increase, it’s time to act now and do everything we can to change our habits.

With this in mind, we thought we’d have a look at the world’s cleanest cities and see if there is anything we can do differently to improve the air quality in the UK.


Honolulu, Hawaii

A popular holiday destination among citizens of the USA, Honolulu is one of the most beautiful cities in North America. Situated on the southern edge of Hawaiian island of O’ahu, it is famous for its exceptional sea views, beautiful patches of greenery and incredible wildlife.

As well as all of this, Honolulu is also one of the cleanest and least polluted cities in the world. Despite its vast population of almost 1 million people, and also being an international business hub, it comes as a surprise that it ranks at 25 on the Air Quality Index.

The Air Quality Index ranks cities based on ground level ozone, particle pollution, carbon monoxide levels and sulphur dioxide levels, ultimately scoring them between 0-500, with 0 being the best and 500 being hazardous.

At the time of writing, the AQI for Honolulu is 13, with the average being only 25.


Zurich, Switzerland

Zurich, the largest city in Switzerland with a population of approximately 430,000, also ranks highly in the list of the world’s cleanest cities. Many of Zurich’s residents opt to use bicycles, trains, buses and subways over their own vehicles, significantly reducing their individual pollution and emissions.

Zurich is one of the world’s largest financial centres, despite its relatively small population, and still manages to keep it’s pollution to a minimum. It’s also a beautiful place to enjoy a city break or weekend away.

On the Air Quality Index, the overall average score for Zurich is a mere 31.

In comparison, London, England’s largest city, has a score of as much as 60 in some places which is in the “moderate” band, compared to Zurich’s “good” rating.


Adelaide, Australia

According to IQ Air, Australia as a country ranks as the 3rd best country in the world for pollution levels. The city of Adelaide is no exception.

Australia is famous for its high temperatures and sprawling outback, but Adelaide is the fifth most populous city in Australia. With a population of 1.34 million, it also ranks among the world’s most liveable cities.

The City of Adelaide Council are actively attempting to make their city as green as possible, providing only 100% renewable electricity to all residents, tracking the city’s carbon emissions and greening their city as much as possible by creating as many green spaces as possible.

If every city took a leaf out of Adelaide’s book, the world would be a much cleaner place.


Calgary, Canada

Calgary’s approach to waste management is one of the main reasons it ranks as one of the least polluted cities in the world. The population of the metropolitan area is approaching 1.4million and is the third largest municipality in Canada, behind only Toronto and Montreal.

Calgary has been voted as the most liveable city in North American in both 2018 and 2019. It has also been a top 5 contender for this award for the past 10 years.

Calgary is known for its technology, manufacturing, aerospace and health & wellness industries and in 2015, had the highest number of millionaires per capita of any major Canadian city.

Despite all of this, it still manages to score an AQI of just 10 and even as low as 4 in certain suburban areas.

Calgary’s city council are “switched on” when it comes to climate change, and in 2013 they reported they had fitted low wattage bulbs in to around 40,000 street lamps to combat pollution and energy usage.


Reykjavik, Iceland

Reykjavik, the capital of Iceland, the world’s least polluted country, has a population of only 129,000 as of 2019. Reykjavik itself ranks at 13 on the AQI, however certain areas away from the centre of the city rank as low as 1.

The city is dedicated to alternative energy sources to keep pollution and emissions to a minimum, with residents enjoying pristine natural resources and living conditions.

Iceland as a whole has a brilliant worldwide reputation for its use of renewable energy, being the only country in the world to obtain 100% of its electricity and heat from renewable sources such as hydro-power and geothermal power.

Being that Iceland is a highly volcanic island, it is much easier for them to harvest the geothermal power, which massively helps towards lowering pollution.


Wellington, New Zealand

For our final city, we’re heading back south to the beautiful island country of New Zealand, famed for its beautiful landscapes, most famously featured in The Hobbit and Lord of the Rings. Wellington is the least polluted city in the whole of Kiwi-land despite being the capital.

Wellington is actually has the cleanest air of all world capitals on the IQ Air list.

As a whole, Wellington scored 43 on the AQI, however certain parts score as low as 2 at some points throughout the year. New Zealand ranks 7th best in the world as a country in terms of pollution levels.

The locals take pride in keeping their city clean, with a population of only 420,000 in the metropolitan area. As a country, 84% of New Zealand’s electricity is renewable and Wellington is one of the world’s most renewable cities with over 70% of its electricity generation coming from renewable sources such as hydro power and geothermal energy, much like Reykjavik.

Due to Wellington’s “small population and geographic isolation” the air is naturally fresher and cleaner, say Mother Nature Network.

Now the world is waking up to climate change, and these cities being excellent examples, why not make a change yourself by switching to a 100% renewable energy supplier like Outfox the Market?