To mark Earth Day (April 22), we've mapped the world according to each country's eco-credentials, as outlined in the 2016 Environmental Performance Index (EPI). Produced by the Yale Center for Environmental Law & Policy, the annual ranking is based on an assessment of the policies of 180 nations, reflecting whether they meeting internationally established environmental targets or, in the absence of agreed targets, how they compare to one another.

Top of the eco-chart is Finland. According to the 2016 EPI report, Finland’s ranking "stems from its societal commitment to achieve a carbon-neutral society". It adds: "Finland’s goal of consuming 38 per cent of their final energy from renewable sources by 2020 is legally binding, and they already produce nearly two-thirds of their electricity from renewable or nuclear power sources."

Iceland is another shining light

Following close behind are Iceland, Sweden and Denmark, three countries renowned for their sound environmental policies. More surprising, perhaps, is the presence of Slovenia, Spain, Portugal and Malta in the top 10. One might also expect Germany do to be doing more to replicate its green policies; it ranks well below France, Denmark, Switzerland and Austria in 30th place.

The 20 most environmentally-friendly countries

Finland - EPI rating: 90.68 Iceland - 90.51 Sweden - 90.43 Denmark - 89.21 Slovenia - 88.98 Spain - 88.91 Portugal - 88.63 Estonia - 88.59 Malta - 88.48 France - 88.2 New Zealand - 88 United Kingdom - 87.38 Australia - 87.22 Singapore - 87.04 Croatia - 86.98 Switzerland - 86.93 Norway - 86.9 Austria - 86.64 Ireland - 86.6 Luxembourg - 86.58

The UK places 12th, with an EPI score of 87.38. The US is 26th, with 84.26. Bosnia and Herzogovina has the worst rating of any European country, placing 120th with a score of 63.28 – below the likes of Iraq, Syria, Libya and China.

It will not come as a shock to see many countries with torrid recent histories populating the bottom of the index. War and civil unrest usually pushes environmental concerns off the agenda. Somalia props up the table, while Eritrea, Afghanistan and Mali also occupy the bottom 10.

A handful of countries do not feature in the ranking; they appear on the map in grey.

Eritrea is among the worst performing countries Credit: GETTY

The world's most polluted countries

We've covered the world's most polluted cities before. Delhi is in a league of its own, as this reporter can attest to; half an hour of sightseeing is enough to leave you with a sore throat. According to the World Health Organisation (WHO), the average concentration of PM 2.5 particles in the Indian city is 150 micrograms per cubic metre of air. PM 2.5 refers to fine particles (2.5 micrometres or smaller in diameter) produced by combustion, including motor vehicles, power plants, forest fires, and some industrial processes. By comparison, London's average is 16.

But what of the most polluted countries? Pinpointing them is a little more problematic. The WHO tracks air quality at 1,622 locations in 92 countries - but all are urban areas. So while Pakistan, Egypt and Mongolia are among the most polluted countries according to the map below, this only refers to pollution in its cities. Air quality in the Karakoram mountain range or the Gobi Desert will, of course, be pristine. Similarly, Russia appears to be among the worst performing countries - but its ranking is based only on air quality in Moscow.

The website aqicn.org crunched 2014 WHO data to help us produce the map above. It shows countries according to the average concentration of PM 2.5 particles in its cities, with figures weighted according to the population of each city. So, if a country's largest city has good air quality, but a handful of small cities have bad air quality, it will perform better overall. Tap on or hover over a country to reveal further statistics, including levels of coarse dust particles (PM10), the result of crushing or grinding operations and dust stirred up by vehicles.

Pakistan's urban areas are, on average, the world's most polluted, followed by Qatar and Afghanistan. Europe's most polluted cities are found in Turkey, Bulgaria and Serbia.

Pakistan's cities are the most polluted on Earth Credit: PAWEL OPASKA

The 20 countries with the most polluted urban areas

Pakistan - average PM 2.5 concentration: 115.7 Qatar - 92.4 Afghanistan - 86 Bangladesh - 83.3 Egypt - 73 UAE - 64 Mongolia - 61.8 India - 60.6 Bahrain - 56.1 Nepal - 50 Ghana - 49 Jordan - 48 China - 41.4 Senegal - 40 Turkey - 39.1 Bulgaria - 38.6 Mauritius - 38.1 Peru - 38 Serbia - 35.8 Iran - 34.2

The countries doing most to protect their land

According to data compiled by the World Bank, 14.8 per cent of the world’s land is currently protected; that’s an improvement on 1990 when that figure was just 8.2 per cent.

Despite being one of the most dangerous and politically volatile countries on the planet, it is Venezuela that leads the way when it comes to conservation, having designated 53.9 per cent of its territory as protected.

Slovenia and, equally surprisingly, the millionaire's playground that is Monaco, came second and third on the list, having protected 53.6 and 53.4 per cent of their territory, respectively.

Angel Falls, Venezuela Credit: Alice Nerr - Fotolia

Countries with the most protected areas

Venezuela (53.9% of total land area) Slovenia (53.6) Monaco (53.4) Bhutan (47.3) Turks and Caicos Islands (44.4) Liechenstein (44.3) Brunei Darussalam (44.1) Seychelles (42.1) Hong Kong (41.8) Greenland (41.2)

The countries that produce the most (and least) CO2 per capita

The map below shows the world according to how much CO2 is produced by each country.

So which is the biggest offender? Well, Qatar belches out more CO2 per capita than anywhere else, followed by Curacao and Latvia. The UK sits 41st, which is poor when you consider that some of our European neighbours are at the cleaner end of the list.

In fact, Denmark is the clear leader when it comes to keeping its emissions down; it produces less CO2 per capita than anywhere else on Earth, followed by Finland and Nigeria.

No country produces more CO2 per capita than Qatar

Countries that belch out the most CO2 per capita

Qatar Curacao Latvia Bahrain United Arab Emirates Trinidad and Tobago Malaysia Saudi Arabia Guatemala United States

Countries that belch out the least CO2 per capita