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Air quality -

A report issued by IQAir, a Swiss company that measures air quality all over the world, compiled a list of the world's most polluted countries, which is updated with data regularly. 

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Fine particulate matter -

The report specifically looks at fine particulate matter (also referred to as PM2.5). This matter is not only one of the smallest, but also one of the most dangerous pollutants.

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Fossil fuels and wildfires -

So what causes PM2.5? Pollutants such as fossil fuels and wildfires are some examples. The fine particles are truly fine, measuring approximately 1/20th of the width of a strand of human hair. 

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Bypass usual defenses -

Due to their tiny size and the fine structure of the particles, they are able to bypass the human body's "usual defenses" and become absorbed directly into the lungs and bloodstream. 

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Air pollution and disease -

According to the World Health Organization, exposure to air pollution has been linked to increased risk of heart disease, stroke, pulmonary diseases, cancer, and other illnesses. Now, let's look at the top 25 most polluted countries in the world.

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25. Laos -

The small nation of Laos is battling big pollution issues. It's PM2.5 concentration is 5.5 times the World Health Organization's guidelines.

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24. Cameroon -

The pollution in the Central African nation of Cameroon is largely caused by wood burning and biomass used for cooking. The nation's PM2.5 concentration is 5.5 times the World Health Organization's guidelines.

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23. Vietnam -

Vietnam is currently suffering from one of the worst air quality levels it has ever experienced. The country's PM2.5 concentration is 5.7 times the World Health Organization's guidelines.

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22. Kuwait -

Kuwait borders countries such as Iraq and Saudi Arabia. The primary driver behind Kuwait's air pollution issues is its bustling oil industry, which furthers air pollution throughout the country. Pictured are Kuwaiti students holding a sign protesting air pollution in their area. 

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21. China -

You might be surprised to see China so far down the list, as some of its cities are the most polluted in the world. But the nation's PM2.5 concentration is just 6.2 times the World Health Organization's guidelines.

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20. Qatar -

The Gulf state is working hard to diminish its air pollution levels, which are largely driven by its production of natural gas. The government has prioritized environmental stability in its Qatar Vision 2030 plan. 

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19. Uzbekistan -

Uzbekistan suffers from a variety of pollutants. Firstly, there is widespread use of older, personal vehicles. Secondly, its industrial production, which includes factories, plants, and other facilities, largely run on the basis of coal. 

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18. Bahrain -

The country of Bahrain makes the list at number 18, with serious air quality issues. Its PM2.5 concentration is 6.4 times the World Health Organization's guidelines. The nation has repeatedly expressed its intention to prioritize environmental issues. 

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17. United Arab Emirates -

The UAE's air quality issues derive from mass personal vehicle use and the emissions associated with it, as well as industrial production. The boom of infrastructure that requires a great deal of energy to be powered is also a contributor. 

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16. The Gambia -

The West African nation makes the list at number 16, holding a PM2.5 concentration tha is seven times the World Health Organization's guidelines.

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15. Indonesia -

Indonesia is made up of over 17,000 islands. The nation's air pollution is largely driven by forest fires. Transportation and energy production are two other significant contributors. 

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14. Ghana -

The West African country struggles with multiple sources of pollution. Its PM2.5 concentration is 7.2 times the World Health Organization's guidelines.

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13. Iraq -

Iraq's most polluted city is Baghdad, followed by Erbil, due to industrial production. The nation's PM2.5 concentration is 7.7 times the World Health Organization's guidelines. 

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12. Egypt -

Egypt has experienced nearly a decade of extensive air pollution issues. Personal vehicle congestion in densely populated cities is one of the major factors driving its poor air quality.

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11. Nigeria -

The nation's largest driver of air pollution is personal vehicle use, many of which run on old motors. The PM2.5 concentration is eight times the World Health Organization's guidelines.

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10. Burundi -

The East African nation rounds the top 10 most polluted countries in the world. The nation's PM2.5 concentration is 8.1 times the World Health Organization's guidelines.

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9. Rwanda -

Air pollution is the number two cause of premature death in the nation, particularly indoor air pollution. The country's PM2.5 concentration is 8.2 times the World Health Organization's guidelines.

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8. Uganda -

The major source of air pollution in Uganda is combustion emissions. Indoor air pollution due to biomass for cooking is also a driving force for the poor air quality that the nation experiences. 

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7. Nepal -

Nepal's industrial production is largely unregulated, meaning environmental degradation is rampant from its production sites. This is the primary source of air quality issues in the nation. Increased forest fires also contribute to air pollution. 

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6. Tajikistan -

The Central Asian nation is struggling to manage its air pollution issues. Its PM2.5 concentration is 9.3 times the World Health Organization's guidelines.

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5. India -

India's urban areas are a huge source of its air pollution issues. In the list of the world's most polluted cities, 13 of India's major production areas feature in the top 20 ranking. 

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4. Democratic Republic of Congo -

The Democratic Republic of Congo is dealing with multiple forms of pollution that pose serious risks to its population. Its PM2.5 concentration is 11.6 times the World Health Organization's guidelines.

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3. Pakistan -

Pollutants emerging from personal vehicle use and factories are the driving force behind the poor air quality that Pakistan experiences. Residents in the nation's largest cities are especially at risk. 

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2. Bangladesh -

Personal vehicle usage, especially due to old motors, in conjunction with industrial fumes are significant sources of air quality pollutants. Toxic black soot is a key issue in production sites. 

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1. Chad -

The nation with the worst air quality is Chad. It is the third leading cause of death in the nation, accounting for 10% of all deaths in 2017 alone. Its PM2.5 concentration is 18.4 times the World Health Organization's guidelines.

Sources: (IQ Air) (CNN)

See also: Understanding the impact of winter on indoor air pollution and tips to improve it

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