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Most polluted countries in the world

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WAKIL KOHSAR/AFP // Getty Images

Most polluted countries in the world

Many of us notice air pollution when it is visible in the form of smog. This is often seen in mountainous areas when weather conditions trap this combination of smoke and sulfur dioxide close to the ground. Around the world, air pollution is caused by numerous factors and can occur not only outdoors, but in the air we breathe indoors.

The World Health Organization has developed guidelines for what concentration of fine particulate matter (PM) is considered acceptable in the air we breathe, citing evidence that PM can cause chronic illness such as respiratory infections, lung cancer, and cardiovascular disease. These guidelines stipulate that PM with a diameter of 2.5 microns (PM2.5) not exceed a 10 micrograms per cubic meter (μg/m3) annual mean.

Stacker has compiled a ranking of the top 50 (out of 194) nations where people have the highest exposures to these dangerous materials—both in rural and urban areas—according to WHO data as of May 2018. We’ve indicated how far above the guidelines PM measures, and also indicated the number of deaths attributed to ambient air pollution in each ranked nation. Finally, we’ve provided a bit of information about each nation’s history, geography, and current political climate; these factors often influence the ways leaders approach the serious threat to daily life and future prosperity that ambient air pollution represents. Continue reading to discover which regions have been impacted the most.


ALSO: U.S. metro areas with the worst air pollution

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adampurser // Pixabay

#50. Cabo Verde

- Concentration of fine particulate matter (PM2.5): 32.0 ug/m3 (3.2x above WHO guidelines)
- Urban concentration: 31.6 ug/m3 (3.2x above WHO guidelines, #50 highest)
- Rural concentration: 33.6 ug/m3 (3.4x above WHO guidelines, #50 highest)
- Deaths attributed to ambient air pollution: 41 per 100,000 (#77 highest)

Cabo Verde is an island nation on an archipelago of volcanic origin. Until 2013, it was called by its Anglicized name, Cape Verde, meaning Green Island. It is situated in the Atlantic Ocean off the northwestern coast of Africa. For this reason, airblown dust from the Sahara Desert causes some of its air pollution. Pollution from local industry is also a factor.

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mayanais // Wikimedia Commons

#49. Jordan

- Concentration of fine particulate matter (PM2.5): 32.1 ug/m3 (3.2x above WHO guidelines)
- Urban concentration: 31.7 ug/m3 (3.2x above WHO guidelines, #49 highest)
- Rural concentration: 38.0 ug/m3 (3.8x above WHO guidelines, #34 highest)
- Deaths attributed to ambient air pollution: 26 per 100,000 (#133 highest)

In 2014, Jordan's Ministry of Environment started an air quality monitoring system. The purpose was to better understand the amounts of air pollution within the kingdom, as well as monitor its sources. The stations are located in heavily populated areas with congested roadways and industrial activity, with the goal of being able to regulate these pollution sources once they are identified.

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Carsten Elert Lorenzen

#48. Gambia

- Concentration of fine particulate matter (PM2.5): 32.2 ug/m3 (3.2x above WHO guidelines)
- Urban concentration: 32.3 ug/m3 (3.2x above WHO guidelines, #48 highest)
- Rural concentration: 31.7 ug/m3 (3.2x above WHO guidelines, #52 highest)
- Deaths attributed to ambient air pollution: 37 per 100,000 (#93 highest)

Also known as the Republic of the Gambia, this nation on the west coast of Africa is small in size but has a population of 1.9 million people. A primary cause of air pollution in Gambia in both rural and urban areas is the burning of wood for cooking and energy.

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Julius // Wikimedia Commons

#47. Togo

- Concentration of fine particulate matter (PM2.5): 32.7 ug/m3 (3.3x above WHO guidelines)
- Urban concentration: 31.2 ug/m3 (3.1x above WHO guidelines, #51 highest)
- Rural concentration: 35.1 ug/m3 (3.5x above WHO guidelines, #46 highest)
- Deaths attributed to ambient air pollution: 45 per 100,000 (#60 highest)

Today's Togo was once part of Togoland, an area of West Africa colonized by the Germans in 1894. That occupation ended during the early days of World War I. The nation was later called French Togoland and finally Togo. Many forms of pollution are a problem in Togo, with the emissions from vehicles such as motorcycles and aging taxi cabs that burn leaded gasoline as fuel.

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Aurel59 // Shutterstock

#46. Benin

- Concentration of fine particulate matter (PM2.5): 33.1 ug/m3 (3.3x above WHO guidelines)
- Urban concentration: 30.4 ug/m3 (3.0x above WHO guidelines, #56 highest)
- Rural concentration: 41.3 ug/m3 (4.1x above WHO guidelines, #27 highest)
- Deaths attributed to ambient air pollution: 48 per 100,000 (#50 highest)

Benin has shifted away from being governed by military dictatorship to free elections. It hopes to move from subsistence agriculture and diversify, in part by developing the tourism business. The population is concentrated in the city of Cotonou, where inefficient motorized vehicles and smuggled high-lead fuels make breathing dangerous at times.

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Charliefleurene // Wikipedia

#45. Ethiopia

- Concentration of fine particulate matter (PM2.5): 34.4 ug/m3 (3.4x above WHO guidelines)
- Urban concentration: 34.0 ug/m3 (3.4x above WHO guidelines, #45 highest)
- Rural concentration: 34.9 ug/m3 (3.5x above WHO guidelines, #47 highest)
- Deaths attributed to ambient air pollution: 32 per 100,000 (#110 highest)

Once known as Abyssinia, this nation of 90 million on the Horn of Africa has the second-highest population in sub-Saharan Africa. In this region, residents rely on biomass fuels such as wood, dung, charcoal, and other materials for indoor cooking and other energy needs. The resulting indoor smoke is the primary source of air pollution illness and death.

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mohigan // Wikimedia Commons

#44. Myanmar

- Concentration of fine particulate matter (PM2.5): 34.7 ug/m3 (3.5x above WHO guidelines)
- Urban concentration: 34.6 ug/m3 (3.5x above WHO guidelines, #42 highest)
- Rural concentration: 34.8 ug/m3 (3.5x above WHO guidelines, #48 highest)
- Deaths attributed to ambient air pollution: 48 per 100,000 (#50 highest)

Also known as Burma, Myanmar has experienced political upheaval and military rule that until recently has made environmental regulation difficult to track; now it's known that the nation has the third-worst air pollution in Southeast Asia. Its sources include indoor burning of biomass fuels as well as coal-fired power plants and industrial agriculture.

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Mohsan Dabiri-e Vaziri // Wikimedia Commons

#43. Iran

- Concentration of fine particulate matter (PM2.5): 35.1 ug/m3 (3.5x above WHO guidelines)
- Urban concentration: 34.4 ug/m3 (3.4x above WHO guidelines, #44 highest)
- Rural concentration: 35.6 ug/m3 (3.6x above WHO guidelines, #41 highest)
- Deaths attributed to ambient air pollution: 34 per 100,000 (#100 highest)

The nation historically known as Persia was one of the great empires of the ancient world. Today it has a population of 79 million and makes its capital in Tehran. That city is greatly affected by airborne contaminants from power plants, polluting vehicles, and even dust storms. The country adopted a clean air law in 2017, allowing it to punish industries and individuals who don't adhere to regulations—which is leading to measurable reductions in pollutants such as carbon dioxide and sulfur.

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Oguz Dikbakan // Shutterstock

#42. Algeria

- Concentration of fine particulate matter (PM2.5): 35.2 ug/m3 (3.5x above WHO guidelines)
- Urban concentration: 34.5 ug/m3 (3.5x above WHO guidelines, #43 highest)
- Rural concentration: 37.6 ug/m3 (3.8x above WHO guidelines, #37 highest)
- Deaths attributed to ambient air pollution: 35 per 100,000 (#99 highest)

Visitors to cities in the North African nation of Algeria notice visible pollution, but the government in Tunisia is taking regulatory steps to improve conditions. The worst sources are road traffic in large cities such as Algiers, Oran, and Constantine.

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Christopher Fynn // Flickr

#41. Bhutan

- Concentration of fine particulate matter (PM2.5): 35.3 ug/m3 (3.5x above WHO guidelines)
- Urban concentration: 35.4 ug/m3 (3.5x above WHO guidelines, #41 highest)
- Rural concentration: 35.3 ug/m3 (3.5x above WHO guidelines, #43 highest)
- Deaths attributed to ambient air pollution: 47 per 100,000 (#56 highest)

This landlocked nation is located in the high-elevation Himalayan mountains south of China. One might think the fresh breezes of this mountainous landscape would be pollution-free, but that's not the case. Officials hope changes in mass transportation, promotion of electric vehicles, and shifts to improved wood stoves will improve conditions.

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cindysayuti // Shutterstock

#40. Burundi

- Concentration of fine particulate matter (PM2.5): 35.6 ug/m3 (3.6x above WHO guidelines)
- Urban concentration: 35.6 ug/m3 (3.6x above WHO guidelines, #40 highest)
- Rural concentration: 35.2 ug/m3 (3.5x above WHO guidelines, #45 highest)
- Deaths attributed to ambient air pollution: 38 per 100,000 (#89 highest)

Decades of political uncertainty have not improved environmental conditions for the people of this landlocked east-central African nation. The United Nations is assisting the nation with a Share the Road program that aims to help reduce air pollution, a non-motorized development project to improve efficient urban mobility. In addition, they hope citizens will be encouraged to use public transportation.

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Ayoub Fajraoui // Wikipedia

#39. Tunisia

- Concentration of fine particulate matter (PM2.5): 35.7 ug/m3 (3.6x above WHO guidelines)
- Urban concentration: 35.7 ug/m3 (3.6x above WHO guidelines, #39 highest)
- Rural concentration: 35.5 ug/m3 (3.6x above WHO guidelines, #42 highest)
- Deaths attributed to ambient air pollution: 56 per 100,000 (#32 highest)

This small country in northern Africa shares borders with Algeria and Libya; it also shares a maritime border with Italy, across the Mediterranean Sea. For more than a century its main industry has been phosphate, which Tunisians mine, refine, and export to be used in fertilizers, plastics, and paints. The waste goes into the sea and into the air.

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TREEAID // Flickr

#38. Burkina Faso

- Concentration of fine particulate matter (PM2.5): 36.8 ug/m3 (3.7x above WHO guidelines)
- Urban concentration: 36.3 ug/m3 (3.6x above WHO guidelines, #37 highest)
- Rural concentration: 37.2 ug/m3 (3.7x above WHO guidelines, #38 highest)
- Deaths attributed to ambient air pollution: 39 per 100,000 (#82 highest)

The northern part of this nation lies in the transition zone between the Sahara Desert and the tropical savanna climate region. Because many people here use wood for cooking and energy, air pollution has increasingly worsened. Officials have introduced a biogas program which will subsidize the installation of 40,000 biodigesters by 2024. These are structures that break down organic matter that is frequently burned and convert them into methane, which can then be piped into a stove.

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Arensond // Wikimedia Commons

#37. Senegal

- Concentration of fine particulate matter (PM2.5): 37.5 ug/m3 (3.8x above WHO guidelines)
- Urban concentration: 39.7 ug/m3 (4.0x above WHO guidelines, #31 highest)
- Rural concentration: 35.2 ug/m3 (3.5x above WHO guidelines, #44 highest)
- Deaths attributed to ambient air pollution: 34 per 100,000 (#100 highest)

This African nation's air quality problems stem from many of the same sources that affect other African countries: lead gasoline-burning vehicles, wood smoke from burning organic material, and even material from sand storms during the dry season. But unlike other countries in West Africa, it has a continuous air quality monitoring system, which can warn people to stay indoors or take other measures during pollution peaks.

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MONUSCO/Myriam Asmani // Wikimedia Commons

#36. Democratic Republic of the Congo

- Concentration of fine particulate matter (PM2.5): 37.6 ug/m3 (3.8x above WHO guidelines)
- Urban concentration: 37.4 ug/m3 (3.7x above WHO guidelines, #33 highest)
- Rural concentration: 37.8 ug/m3 (3.8x above WHO guidelines, #36 highest)
- Deaths attributed to ambient air pollution: 40 per 100,000 (#81 highest)

Decades of political and social instability have not helped the people overcome ill health from air pollution in this vast country formerly known as Zaire. Congo's largest city, Kinshasa, is particularly affected by the typical factors of wood smoke, roadways choked by polluting vehicles, and industrialization. One study measures the extent of pollution there caused by man-made heavy metals particulate such as arsenic, cadmium, and lead. These affect the atmosphere, soils, and water, impacting all members of the food chain.

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Andries Oudshoorn // Wikimedia Commons

#35. Oman

- Concentration of fine particulate matter (PM2.5): 38.2 ug/m3 (3.8x above WHO guidelines)
- Urban concentration: 36.2 ug/m3 (3.6x above WHO guidelines, #38 highest)
- Rural concentration: 40.0 ug/m3 (4.0x above WHO guidelines, #32 highest)
- Deaths attributed to ambient air pollution: 20 per 100,000 (#159 highest)

Located on the Arabian Peninsula, the Sultanate of Oman has experienced rapid economic development and improved living standards, which has let to more people being concentrated in cities. But whether they are located in urban or rural areas, people are exposed to air pollution from energy production, transportation, and industrial facilities such as cement, chemical, and oil refineries. The government has identified some opportunities for action, such as approving a national health adaptation strategy.

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gpzagan // Pixabay

#34. Gabon

- Concentration of fine particulate matter (PM2.5): 38.5 ug/m3 (3.9x above WHO guidelines)
- Urban concentration: 37.8 ug/m3 (3.8x above WHO guidelines, #32 highest)
- Rural concentration: 38.8 ug/m3 (3.9x above WHO guidelines, #33 highest)
- Deaths attributed to ambient air pollution: 34 per 100,000 (#100 highest)

Located in West-Central Africa, Gabon has 13 national parks—including rainforests and grass savanna spaces—that are habitats to animals like gorillas and hippos. Natural resources such as oil and gas make this one of the wealthier nations in Africa but industrialization has harmed its air quality. In response, Gabon is installing multiple hybrid solar plants in partnership with a French utility company.

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Julien Harneis // Pixabay

#33. Congo

- Concentration of fine particulate matter (PM2.5): 38.7 ug/m3 (3.9x above WHO guidelines)
- Urban concentration: 36.4 ug/m3 (3.6x above WHO guidelines, #36 highest)
- Rural concentration: 41.4 ug/m3 (4.1x above WHO guidelines, #26 highest)
- Deaths attributed to ambient air pollution: 33 per 100,000 (#106 highest)

Republic of the Congo (not to be confused with the Democratic Republic of the Congo) has air pollution sources that are comparable to other countries in Africa that burn wood for heat and energy. This leads to air pollution and potentially deforestation, which in turn causes other environmental troubles.

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GEORGE OURFALIAN/AFP // Getty Images

#32. Syrian Arab Republic

- Concentration of fine particulate matter (PM2.5): 39.4 ug/m3 (3.9x above WHO guidelines)
- Urban concentration: 37.4 ug/m3 (3.7x above WHO guidelines, #34 highest)
- Rural concentration: 49.2 ug/m3 (4.9x above WHO guidelines, #15 highest)
- Deaths attributed to ambient air pollution: 43 per 100,000 (#68 highest)

Syria is a country with numerous natural and fuel resources such as petroleum, phosphates, chrome and manganese ores, asphalt, iron ore, rock salt, marble, and gypsum. It is also in the midst of a years-long civil war, making it difficult for the government to launch environmental clean-up campaigns; one study reports the war itself has had various environmental impacts, including air pollution.

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atimedia // Pixabay

#31. United Arab Emirates

- Concentration of fine particulate matter (PM2.5): 39.4 ug/m3 (3.9x above WHO guidelines)
- Urban concentration: 37.2 ug/m3 (3.7x above WHO guidelines, #35 highest)
- Rural concentration: 40.2 ug/m3 (4.0x above WHO guidelines, #29 highest)
- Deaths attributed to ambient air pollution: 15 per 100,000 (#176 highest)

The UAE is situated on the Arabian Peninsula of in the Middle East. Its largest emirate (or political territory) is Dubai, which has become a global destination for the wealthy. Air quality is compromised by burning, industrialization, traffic density, and natural causes of airborne particles such as dust storms. To address the public health concern, sensors and filters are being installed; these alone won't stop the pollution, but at least can help people protect themselves when conditions are acute.

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Brybry26 // Wikimedia Commons

#30. Tajikistan

- Concentration of fine particulate matter (PM2.5): 40.0 ug/m3 (4.0x above WHO guidelines)
- Urban concentration: 42.8 ug/m3 (4.3x above WHO guidelines, #23 highest)
- Rural concentration: 37.8 ug/m3 (3.8x above WHO guidelines, #35 highest)
- Deaths attributed to ambient air pollution: 50 per 100,000 (#43 highest)

This small, landlocked country in Central Asia (which has seen much political upheaval in recent decades) has experienced increased energy production, industrialization, and urban development—and increased pollution as a result. Tajikistan has noticed recent improvements in air quality, which can be attributed to the UNECE Convention on Long-range Transboundary Air Pollution and its management strategies.

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CharlesFred // Wikimedia Commons

#29. Djibouti

- Concentration of fine particulate matter (PM2.5): 40.4 ug/m3 (4.0x above WHO guidelines)
- Urban concentration: 41.0 ug/m3 (4.1x above WHO guidelines, #28 highest)
- Rural concentration: 40.1 ug/m3 (4.0x above WHO guidelines, #30 highest)
- Deaths attributed to ambient air pollution: 43 per 100,000 (#68 highest)

This East African nation lies in a strategic location—controlling shipping access to the Red Sea and Suez Canal—and the United States' largest military base in Africa, Camp Lemonnier, is located there. Water pollution caused by shipping has had a major impact in the nation, and air pollution is at its worst around the coastal zone near the capital city, Djibouti City.

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Ganzorig Miimaa // Shutterstock

#28. Mongolia

- Concentration of fine particulate matter (PM2.5): 40.4 ug/m3 (4.0x above WHO guidelines)
- Urban concentration: 49.5 ug/m3 (5.0x above WHO guidelines, #17 highest)
- Rural concentration: 36.9 ug/m3 (3.7x above WHO guidelines, #39 highest)
- Deaths attributed to ambient air pollution: 49 per 100,000 (#45 highest)

This large, landlocked, and ancient nation lies near Russia and China. Much of its landscape is mountainous with sparse vegetation, limiting its habitability: at 3 million people, it's one of the least populated countries in the world. Approximately half of the population lives in the capital city of Ulaanbaatar, where air pollution is caused by factors such as industrialization and polluting vehicles. The air is at its worst during its long winter season, during which particulate matter is less likely to be dispersed by wind.

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RWANDA ENVIRONMENT MANAGEMENT AUTHORITY REMA // Flickr

#27. Rwanda

- Concentration of fine particulate matter (PM2.5): 40.7 ug/m3 (4.1x above WHO guidelines)
- Urban concentration: 40.7 ug/m3 (4.1x above WHO guidelines, #30 highest)
- Rural concentration: 44.0 ug/m3 (4.4x above WHO guidelines, #23 highest)
- Deaths attributed to ambient air pollution: 24 per 100,000 (#142 highest)

This landlocked, hilly nation of 11.5 million has one of the highest population densities in sub-Saharan Africa. War, political upheaval, and ethnic tensions have made it difficult for Rwanda to tackle its pollution problems, in spite of some international assistance. The government is studying the problem and identifying sources of pollution, such as vehicle emissions; it has discovered that pollution readings drop on holiday and car-free days.

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Maxim VanBest Dynasty // Wikimedia Commons

#26. Mauritania

- Concentration of fine particulate matter (PM2.5): 40.8 ug/m3 (4.1x above WHO guidelines)
- Urban concentration: 41.7 ug/m3 (4.2x above WHO guidelines, #25 highest)
- Rural concentration: 40.0 ug/m3 (4.0x above WHO guidelines, #31 highest)
- Deaths attributed to ambient air pollution: 44 per 100,000 (#65 highest)

Much of this West African nation is covered in the sand of the Sahara Desert. Its largest city is the capital, Nouakchott, with about 3.4 million residents. Sand dust is inevitable, but 20 years of drought have made it worse. The drought has also forced people who once lived a nomadic life to move into the cities, where vehicular traffic and industry have increased.

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EU Civil Protection and Humanitarian Aid // Flickr

#25. South Sudan

- Concentration of fine particulate matter (PM2.5): 41.1 ug/m3 (4.1x above WHO guidelines)
- Urban concentration: 40.9 ug/m3 (4.1x above WHO guidelines, #29 highest)
- Rural concentration: 41.1 ug/m3 (4.1x above WHO guidelines, #28 highest)
- Deaths attributed to ambient air pollution: 45 per 100,000 (#60 highest)

Civil wars in South Sudan have killed an estimated 383,000 people as of 2018. Coupled with other crises such as Ebola outbreaks, this nation has faced devastation both to people and the environment. In response, the World Health Organization is working with the Ministry of Health on a draft environmental health policy.

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JOE KLAMAR/AFP // Getty Images

#24. Turkey

- Concentration of fine particulate matter (PM2.5): 42.0 ug/m3 (4.2x above WHO guidelines)
- Urban concentration: 41.2 ug/m3 (4.1x above WHO guidelines, #26 highest)
- Rural concentration: 43.2 ug/m3 (4.3x above WHO guidelines, #24 highest)
- Deaths attributed to ambient air pollution: 46 per 100,000 (#57 highest)

Home to ancient nations and tribes that date back to 10,000 B.C., the Republic of Turkey is today a major tourist destination among European travelers in particular—in spite of recent military offenses. Public health officials warn that its air pollution can be damaging to pregnant women and young children.

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12019 // Pixabay

#23. Eritrea

- Concentration of fine particulate matter (PM2.5): 42.4 ug/m3 (4.2x above WHO guidelines)
- Urban concentration: 41.1 ug/m3 (4.1x above WHO guidelines, #27 highest)
- Rural concentration: 42.9 ug/m3 (4.3x above WHO guidelines, #25 highest)
- Deaths attributed to ambient air pollution: 43 per 100,000 (#68 highest)

This east African nation has a mixed Afro-Asiatic population, with religious and cultural divides as a contributor to decades of human rights violations and unrest. The consequence of these has been environmental damage that has led to drought; combined with widespread use of charcoal for cooking, increased air pollution is one of Eritrea's numerous growing problems.

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Maher A. A. Abdussalam // Wikimedia Commons

#22. Libya

- Concentration of fine particulate matter (PM2.5): 44.2 ug/m3 (4.4x above WHO guidelines)
- Urban concentration: 41.7 ug/m3 (4.2x above WHO guidelines, #24 highest)
- Rural concentration: 44.9 ug/m3 (4.5x above WHO guidelines, #22 highest)
- Deaths attributed to ambient air pollution: 43 per 100,000 (#68 highest)

More than 90% of this North African country is desert or semi-desert, and well over 90% of the population lives along the Mediterranean coast. The Saharan region of the country is hot, dry, and prone to dust-laden wind storms several times a year. Although politically volatile, Libya has been party to international agreements dealing with biodiversity, climate change, desertification, and ozone layer protection.

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Dan // Flickr

#21. Yemen

- Concentration of fine particulate matter (PM2.5): 45.0 ug/m3 (4.5x above WHO guidelines)
- Urban concentration: 44.3 ug/m3 (4.4x above WHO guidelines, #22 highest)
- Rural concentration: 46.5 ug/m3 (4.6x above WHO guidelines, #20 highest)
- Deaths attributed to ambient air pollution: 55 per 100,000 (#36 highest)

This desert country on the Red Sea supports a population of 26 million, with its capital Sana'a as its largest city. Many in Yemen drive cars that take leaded gasoline, and its oil production industry contributes to higher pollution around the coastal areas.

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Embassy of Equatorial Guinea // Flickr

#20. Equatorial Guinea

- Concentration of fine particulate matter (PM2.5): 45.9 ug/m3 (4.6x above WHO guidelines)
- Urban concentration: 49.1 ug/m3 (4.9x above WHO guidelines, #18 highest)
- Rural concentration: 45.5 ug/m3 (4.6x above WHO guidelines, #21 highest)
- Deaths attributed to ambient air pollution: 51 per 100,000 (#41 highest)

Five inhabited islands and a section of the African mainland comprise this tropical nation. There is great biodiversity in Equatorial Guinea, but the country is dependent on its oil economy, which is a major source of pollution. UNICEF's annual report from 2017 describes myriad challenges facing this nation, but also areas of health and wellbeing where improvements have been noted.

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Oxfam East Africa // Wikimedia Commons

#19. Sudan

- Concentration of fine particulate matter (PM2.5): 47.9 ug/m3 (4.8x above WHO guidelines)
- Urban concentration: 46.8 ug/m3 (4.7x above WHO guidelines, #20 highest)
- Rural concentration: 48.3 ug/m3 (4.8x above WHO guidelines, #18 highest)
- Deaths attributed to ambient air pollution: 56 per 100,000 (#32 highest)

The Republic of Sudan was once the largest in Africa until it broke apart into Sudan and South Sudan in 2011. Previous to that, conflict in its western region of Darfur caused environmental and humanitarian crises which are still unresolved. Finding up-to-date detailed reports on current environmental conditions is challenging, but the United Nations has studied conditions in Sudan since the ending of a civil war in 2005—noting key challenges in the country such as environmental degradation, deforestation, and climate change.

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Lars Schoebitz // Flickr

#18. Uganda

- Concentration of fine particulate matter (PM2.5): 48.4 ug/m3 (4.8x above WHO guidelines)
- Urban concentration: 48.7 ug/m3 (4.9x above WHO guidelines, #19 highest)
- Rural concentration: 47.1 ug/m3 (4.7x above WHO guidelines, #19 highest)
- Deaths attributed to ambient air pollution: 32 per 100,000 (#110 highest)

Effects of air pollution in Uganda's largest city, Kampala, are primarily caused by vehicle emissions. Across the semi-arid country, mining activities and wood burning for cooking and fuel are also factors. Officials say that encouraging people to walk instead of drive would help solve the problem, but others note air pollution isn't treated as a serious problem because its effects are largely invisible.

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Heinrich-Böll-Stiftung // Flickr

#17. Nigeria

- Concentration of fine particulate matter (PM2.5): 48.7 ug/m3 (4.9x above WHO guidelines)
- Urban concentration: 46.3 ug/m3 (4.6x above WHO guidelines, #21 highest)
- Rural concentration: 56.5 ug/m3 (5.7x above WHO guidelines, #8 highest)
- Deaths attributed to ambient air pollution: 76 per 100,000 (#17 highest)

Africa's largest country by population faces continued ethnic, religious, and political tensions. Nigeria—whose largest city, Lagos, is home to 21 million people—has had the most fatalities from air pollution in Africa. Some of the culprits include fumes from generators, vehicle emissions, and crop burning. The nation's maternal mortality is the highest in the world, much of it attributed to pollution.

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Max Pixel

#16. China

- Concentration of fine particulate matter (PM2.5): 49.2 ug/m3 (4.9x above WHO guidelines)
- Urban concentration: 51.0 ug/m3 (5.1x above WHO guidelines, #15 highest)
- Rural concentration: 35.7 ug/m3 (3.6x above WHO guidelines, #40 highest)
- Deaths attributed to ambient air pollution: 81 per 100,000 (#14 highest)

The most populous country on earth, the People's Republic of China contains some 1,367 million people. While its capital is Beijing, its most populated city is Shanghai, with about 23.47 million in the overall metropolitan area. Recent good news is that in 2018, a crackdown on pollution has shown some results; smog emissions in Beijing and a surrounding industrial area fell by at least 12% in 2018. A satellite map is available to observe levels of air pollution over China and its changes over time.

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Global Panorama // Pixabay

#15. Central African Republic

- Concentration of fine particulate matter (PM2.5): 49.5 ug/m3 (5.0x above WHO guidelines)
- Urban concentration: 51.2 ug/m3 (5.1x above WHO guidelines, #14 highest)
- Rural concentration: 49.0 ug/m3 (4.9x above WHO guidelines, #16 highest)
- Deaths attributed to ambient air pollution: 62 per 100,000 (#28 highest)

Like many developing African nations, Central African Republic has gone through periods of instability. However, this former French colony of five million has recognized how environmental conditions harm the health of its people. In 2013, it joined the Climate and Clean Air Coalition, and is now focused on reducing agricultural open-burning and other emission sources.

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David Stanley // Flickr

#14. Chad

- Concentration of fine particulate matter (PM2.5): 53.0 ug/m3 (5.3x above WHO guidelines)
- Urban concentration: 50.8 ug/m3 (5.1x above WHO guidelines, #16 highest)
- Rural concentration: 53.6 ug/m3 (5.4x above WHO guidelines, #11 highest)
- Deaths attributed to ambient air pollution: 83 per 100,000 (#9 highest)

This former French colony in North Central Africa has experienced a fairly stable period since 1990. Chad is challenged in part by being part of an area stretching from Senegal to Ethiopia known as the Meningitis belt—identified by researchers as a region where the practice of breaking smoke from indoor fires contributes to bacterial meningitis.

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WAKIL KOHSAR/AFP // Getty Images

#13. Afghanistan

- Concentration of fine particulate matter (PM2.5): 53.2 ug/m3 (5.3x above WHO guidelines)
- Urban concentration: 59.9 ug/m3 (6.0x above WHO guidelines, #10 highest)
- Rural concentration: 48.7 ug/m3 (4.9x above WHO guidelines, #17 highest)
- Deaths attributed to ambient air pollution: 49 per 100,000 (#45 highest)

This nation of 26.5 million is touched by three geographical regions: the Middle East, the Indian subcontinent, and Central Asia. Its location has made it a player in geopolitical battles over many decades, with military conflicts being a central fact of life for its people. Residents of the capital city of Kabul face worsening air quality in winter when the use of low-quality fuel fills the air with emissions. Officials recommend frequent hand and face washing, as well as gargling and wearing facemasks, to protect the health of Kabul's six million residents.

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ARIF ALI/AFP // Getty Images

#12. Pakistan

- Concentration of fine particulate matter (PM2.5): 55.2 ug/m3 (5.5x above WHO guidelines)
- Urban concentration: 56.2 ug/m3 (5.6x above WHO guidelines, #13 highest)
- Rural concentration: 52.0 ug/m3 (5.2x above WHO guidelines, #14 highest)
- Deaths attributed to ambient air pollution: 63 per 100,000 (#26 highest)

Bordering on Afghanistan, Pakistan's population is 188 million, with approximately one million in the capital of Islamabad. The nation was created in 1947 and is composed of desert and mountainous terrain. A resident of Karachi sued the government in 2018 for failing to control air pollution; the environmental protection authorities are adding air quality monitors and enforcing emission regulations as a result.

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YASSER AL-ZAYYAT/AFP // Getty Images

#11. Kuwait

- Concentration of fine particulate matter (PM2.5): 57.2 ug/m3 (5.7x above WHO guidelines)
- Urban concentration: 58.9 ug/m3 (5.9x above WHO guidelines, #11 highest)
- Rural concentration: 52.5 ug/m3 (5.3x above WHO guidelines, #13 highest)
- Deaths attributed to ambient air pollution: 37 per 100,000 (#93 highest)

An oil-rich country on the Arabian Peninsula, Kuwait is a constitutional hereditary emirate, also known as a constitutional monarchy. It has no rivers or mountains but is flat, sandy, and borders on the Persian Gulf. Air quality readings in Kuwait can be observed thanks to a partnership of the U.S. Department of State and the EPA that has led to the installation of air quality monitors at American embassies around the globe.

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Mstyslav Chernov // Wikimedia Commons

#10. Iraq

- Concentration of fine particulate matter (PM2.5): 57.7 ug/m3 (5.8x above WHO guidelines)
- Urban concentration: 60.1 ug/m3 (6.0x above WHO guidelines, #9 highest)
- Rural concentration: 54.8 ug/m3 (5.5x above WHO guidelines, #10 highest)
- Deaths attributed to ambient air pollution: 34 per 100,000 (#100 highest)

Iraq has experienced conflict for several decades—including the U.S.'s ongoing military presence since its invasion of the country—leading to harmful environmental degradation. Researchers have determined that rising birth defects and cancers in Iraq in recent years can be connected to neurotoxicants in the environment—the result of numerous explosions and other wartime ammunition releases.

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dougsyme // Flickr

#9. Bangladesh

- Concentration of fine particulate matter (PM2.5): 58.3 ug/m3 (5.8x above WHO guidelines)
- Urban concentration: 58.6 ug/m3 (5.9x above WHO guidelines, #12 highest)
- Rural concentration: 52.9 ug/m3 (5.3x above WHO guidelines, #12 highest)
- Deaths attributed to ambient air pollution: 51 per 100,000 (#41 highest)

The People's Republic of Bangladesh came into being in 1971. Located in Southern Asia where the Ganges River Delta meets the Bay of Bengal, its geography and topography make it prone to frequent monsoons and flooding. Although its land is only about the size of Iowa, Bangladesh's population is around 164 million people—and its capital city, Dhaka, has the worst level of air pollution of any city in the world.

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XAVIER GALIANA/AFP/Getty Images

#8. India

- Concentration of fine particulate matter (PM2.5): 65.2 ug/m3 (6.5x above WHO guidelines)
- Urban concentration: 68.0 ug/m3 (6.8x above WHO guidelines, #7 highest)
- Rural concentration: 55.9 ug/m3 (5.6x above WHO guidelines, #9 highest)
- Deaths attributed to ambient air pollution: 82 per 100,000 (#12 highest)

After India gained independence from Britain in 1947, the subcontinent was partitioned into smaller countries—including neighboring Pakistan, which was later subdivided to form Bangladesh. India remains the second-most-populous nation in the world. Lung cancer is becoming increasingly common in younger non-smokers, which medical research traces to the increasingly polluted air.

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U.S. Fish and Wildlife Service Headquarters

#7. Cameroon

- Concentration of fine particulate matter (PM2.5): 65.3 ug/m3 (6.5x above WHO guidelines)
- Urban concentration: 65.4 ug/m3 (6.5x above WHO guidelines, #8 highest)
- Rural concentration: 65.1 ug/m3 (6.5x above WHO guidelines, #7 highest)
- Deaths attributed to ambient air pollution: 62 per 100,000 (#28 highest)

The area of east Africa known as the Republic of Cameroon has been cobbled together from generations of being ruled by a succession of nations including Portugal, Spain, Germany, and France. The first study of air quality in three major cities in Cameroon was conducted in 2014; researchers concluded that further study needs to be done in order to develop a plan for reducing the problem.

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Kit // Pixabay

#6. Bahrain

- Concentration of fine particulate matter (PM2.5): 69.0 ug/m3 (6.9x above WHO guidelines)
- Urban concentration: 69.0 ug/m3 (6.9x above WHO guidelines, #6 highest)
- Rural concentration: 70.7 ug/m3 (7.1x above WHO guidelines, #3 highest)
- Deaths attributed to ambient air pollution: 15 per 100,000 (#176 highest)

The Kingdom of Bahrain, which gained independence from Britain in 1971, is an archipelago of 33 islands in the Persian Gulf that are located off the eastern coast of Saudi Arabia. Its chief industry, oil production, contributes to the country's emissions problem—but there is a plan in place to monitor air quality and take measures to combat harmful effects of pollution.

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NigerTZai // Wikimedia Commons

#5. Niger

- Concentration of fine particulate matter (PM2.5): 70.8 ug/m3 (7.1x above WHO guidelines)
- Urban concentration: 73.0 ug/m3 (7.3x above WHO guidelines, #5 highest)
- Rural concentration: 69.7 ug/m3 (7.0x above WHO guidelines, #4 highest)
- Deaths attributed to ambient air pollution: 69 per 100,000 (#25 highest)

Situated on the southern border of the Sahara desert, the Republic of Niger is dry, drought-prone, and one the poorest countries in the world. It also has the highest birthrate in the world, with its current population of 22 million people set to double in 17 years. Pollution sources from burning of both organic materials and garbage, in addition to cook stoves, vehicle exhaust and toxic road dust.

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Peter Dowley // Flickr

#4. Saudi Arabia

- Concentration of fine particulate matter (PM2.5): 78.4 ug/m3 (7.8x above WHO guidelines)
- Urban concentration: 86.7 ug/m3 (8.7x above WHO guidelines, #3 highest)
- Rural concentration: 75.1 ug/m3 (7.5x above WHO guidelines, #2 highest)
- Deaths attributed to ambient air pollution: 37 per 100,000 (#93 highest)

When oil was discovered there in the 1930s, the Kingdom of Saudi Arabia developed quickly and is now one of the world's wealthiest nations. The capital city, Riyadh, with a population of 4.7 million, has the worst air pollution in the Arab world—partly because of blowing desert sand and partly because of the oil industry.

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Sturm58 // Wikimedia Commons

#3. Egypt

- Concentration of fine particulate matter (PM2.5): 79.3 ug/m3 (7.9x above WHO guidelines)
- Urban concentration: 79.6 ug/m3 (8.0x above WHO guidelines, #4 highest)
- Rural concentration: 69.4 ug/m3 (6.9x above WHO guidelines, #5 highest)
- Deaths attributed to ambient air pollution: 70 per 100,000 (#22 highest)

Formally known as the Arab Republic of Egypt, the country is well-known for its ancient history, including the pyramids at Giza near the capital city of Cairo. The country's Ministry of Environment is taking steps to reduce what is known as the black cloud over Cairo; targets include industrial emissions and vehicle exhaust, as well as farming practices that involve burning off harvested rice fields.

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Mahesan Chandrasekaran // Shutterstock

#2. Qatar

- Concentration of fine particulate matter (PM2.5): 90.3 ug/m3 (9.0x above WHO guidelines)
- Urban concentration: 91.7 ug/m3 (9.2x above WHO guidelines, #2 highest)
- Rural concentration: 81.3 ug/m3 (8.1x above WHO guidelines, #1 highest)
- Deaths attributed to ambient air pollution: 13 per 100,000 (#181 highest)

The State of Qatar is an independent emirate on a small peninsula extending north from the larger Arabian Peninsula into the Persian Gulf. Being an oil-rich area and its development of hydrocarbon resources has helped the emirate become economically stable. Officials are studying ways to balance economic growth with the health and well-being of its 2.6 million citizens. The more Qatar becomes important on the world stage, through events such as hosting the 2022 World Cup, the more its resources will be developed.

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PRAKASH MATHEMA/AFP // Getty Images

#1. Nepal

- Concentration of fine particulate matter (PM2.5): 94.3 ug/m3 (9.4x above WHO guidelines)
- Urban concentration: 99.5 ug/m3 (9.9x above WHO guidelines, #1 highest)
- Rural concentration: 68.3 ug/m3 (6.8x above WHO guidelines, #6 highest)
- Deaths attributed to ambient air pollution: 76 per 100,000 (#17 highest)

Situated in the towering Himalayan mountains, this multiethnic, multilingual, multi-religious country is home to 31 million people. Air quality monitors in its capital Kathmandu, home to 1.5 million people, shows that increasing emissions from vehicle exhaust and industry are harming health, particularly in the winter. Farming practices such as brush fires and wood cooking in rural regions are also taking a toll. One of the most alarming effects of Nepal's environmental decline is seen in the changes to nearby mountain glaciers.

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