Top 10 Smoggiest Countries in the World

The word “smog” has existed since one Dr. H.A. des Voeux, treasurer of the Coal Smoke Abatement Society, coined it in reference to London by combining “smoke” and “fog” to describe the “black fog” that was “not unknown in other large cities.”

More than a century later, “smog” is a commonplace word and phenomenon. Air pollution has become a major threat to public health around the globe, with urban outdoor air pollution estimated to cause 1.3 million deaths worldwide per year according to the World Health Organization (WHO). The air that residents of cities around the world breathe is full of particulate matter (which contains sulfate, nitrates, ammonia, sodium chloride, carbon and mineral dust) and ozone (which is created when sunlight reacts with pollutants from vehicle and industrial emissions). These substances can cause respiratory problems, trigger asthma, irritate eyes and much more.

Drawing in part on WHO data, here are ten of the smoggiest countries on earth based on measures including the number of parts per million of particles smaller than 10 micrometers (PM10) floating around in the air. Notably, many are in the Middle East and Asia.

1. Iran

Fire altar (modern version)

(Photo of Ahvaz via dynamosquito/Flickr)

Four cities in Iran are among the ten smoggiest in the world according to the WHO. One of the country’s largest, Ahvaz, is listed as the most smoggy, period. Located in southwestern Iran, Ahvaz is the capital of Khuzestan province, a region that traces its history all the way back to one of the oldest cities ever, Susa, one of the capitals of the ancient Achaemenid Persian Empire.

Modern-day Ahvaz has an average PM10 of 372 as a result of untrammeled development in the form of heavy industries including iron and steel plants and oil drilling. In the summer, temperatures can average 50-55 degrees Celsius.

2. Mongolia


(Photo of Ulaanbaatar via AaverageJoe/Flickr)

Located at an elevation of about 4,300 feet, Ulaanbaatar is the capital of Mongolia and a place where the old (a Buddhist monastic center was founded there  in 1639) meets the modern (the city is connected by rail to both the Trans-Siberian Railway in Russia and the Chinese railway system). The WHO ranks Ulaanbaatar as the world’s second most polluted city, with a PM10 of 279 that stems from both coal-fueled power plants and stoves used for heating and cooking in the city’s yurt quarters.

With a burgeoning economy — due in part to copper and coal mines —  a huge new coal fire power plant that uses “newer, cleaner” technology is under construction. But government officials have also shown interest in wind energy and wind turbines have been erected outside Ulaanbaatar.

3. India

View of West of Delhi

(Photo of Delhi via jepoirrier/Flickr)

India’s capital city of Delhi has more than four million registered vehicles — many powered by diesel fuel — and that is one reason it is ranked as the twelfth most polluted in the world with a PM10 of 198. The city’s poor air quality is also due to industry (including power plants) and road dust.

Air pollution is a huge problem for all of India. Other Indian cities noted by the WHO as being especially polluted are Lucknow with a PM10 of 186, Kolkata with a PM10 of 148 and Mumbai with a PM10 of 132. The burning of wood, agricultural waste and other materials has resulted in a near-perpetual haze hanging over urban and rural areas of India (and neighboring Bangladesh) that is visible in satellite photos.


4. Pakistan


(Photo of Peshawar via Omer Wazir/Flickr)

The Pakistani city of Quetta is (along with the Indian city of Ludhiana) ranked by the WHO as the fourth-most polluted in the world. Peshawar, an ancient city situated at one end of the legendary Khyber Pass, on the border of Pakistan and Afghanistan — that is, at the very crossroads of Central Asia and South Asia — is ranked seventh worse; a number of other cities (Lahore, Karachi and Islamabad) are ranked by the WHO as among the 15 most polluted.

Peshawar’s PM10 of 219 is  the result of a rapid increase in vehicular traffic as well as the uses of hundreds of coal-burning brick kilns. As a whole, “highly inefficient energy use” is noted as a reason for the air pollution throughout Pakistan as well as an increase in industrial activity (including marble and steel factories) without regulation and the burning of materials including plastic.

5. Botswana

Gaborone, Botswana

(Photo of Gaborone via pmecologic/Flickr)

Botswana’s capital, Gaborone, is listed as the eighth most polluted city in the world by the WHO with a PM10 of 216. A steep rise in the use of vehicles is one reason; another is the use of fire wood, paraffin and animal dung to start fires for cooking and other purposes. Nor is Botswana the only country in Africa with serious pollution: Dakar, the capital of Senegal, is 28th with a PM10 of 156 and Lagos, Nigeria’s capital, has a PM10 of 122 and is ranked 46th worst.

Currently, Botswana is a “lightly industrialized country with a relatively sparse population” and, outside Gaborone, “air pollution is not perceived to be a major problem at present.” The government’s national development strategy seeks to expand light industry: can Botswana learn from what has happened in Iran, India and Pakistan?

6. Saudi Arabia

Riyadh, birdview

(Photo of Riyadh via Jackson Lee/Flickr)

The WHO ranks Saudi Arabia’s capital city of Riyadh as the 23rd most polluted in the world, just after the United Arab Emirates city of Al Ain. Four other Saudi cities are also listed in the top 50 smoggiest cities in the world and one report calls Saudi Arabia the world’s largest produced and exporter of petroleum, the fifth most polluted country in the entire world. The report specifically notes that the country’s 2,175-mile coastline has been the victim of heavy-duty environmental pollution due to desalination, sewage outflows and oil and chemical plumes.

Riyadh itself has a PM10 of 157 according to the WHO. The city’s municipal government says that 96 percent of the causes of its air pollution are “natural” (due to the city’s location and climate), but other sources attribute this to refineries and power plants and the use of cars and other vehicles.


7. China

Tiananmen Square and Gate of Heavenly Peace, Beijing

(Photo of Beijing via SFCityscape/Flickr)

China’s capital of Beijing became notorious for its “airpocalypse” last winter. But it is far from the smoggiest; in the WHO’s ranking, Beijing is tied with the Saudi Arabian city of Dammam for being the 47th most polluted cities in the world, with an average PM10 of 121.

The most polluted city in China is Lanzhou, with a PM10 of 150; it is the 25th most polluted city in the world due to an accelerated pace of development — the city has textile mills, plants that process rubber and fertilizer, and an oil refinery – that has been ongoing since 1949. Another city that bears mention is Linfen, located in the central-north province of Shanxi and the center of China’s coal industry. Wuth mines (legal and illegal) filling Linfen’s hills, its residents “literally” choke on coal dust and have high rates of bronchitis, pneumonia and lung cancer.


8. Egypt

Cairo Air Pollution with smog - Pyramids1

(Photo of Cairo via ninahale/Flickr)

According to the WHO, Cairo is the 33rd most polluted in the world with a PM10 of 138 — no wonder some have spoken of a “black cloud” over the city. Industry and transportation are some of the main factors, along with the burning of waste in open air.

Cairo’s tall buildings, narrow streets and lack of rainfall make it (like New York City) a “thermal island”; a number of factories are also located around it. Cairo residents suggest that another source of pollution could be from the burning of rice straw by farmers in Sharkiya governorate, which is where much of Egypt’s rice crop is planted.

Both urban and rural residents face additional challenges due to concerns about water supplies. About 97 percent of the country’s water supply comes from the Nile River, which has been polluted by sewage and industrial waste.

9. Mexico


(Photo of Mexicali via Mario Carboni/Flickr)

Mexico City ‘s air pollution has improved since 1992, when the United Nations named it “the most polluted city on the planet.” Thanks to efforts to reformulate gasoline, close or move factories and restrict drivers, the city’s ozone and other air pollutants are now ranked at about the same levels as those of Los Angeles.

Other Mexican cities including Mexicali on the U.S. border also suffer from serious air pollution. With a PM10 of 137, Mexicali is ranked as the 34th most polluted. Industry and urban growth are not only culprits in reducing air quality but have also played a role in making the New River, which flows north into California, the most polluted waterway in the U.S. — a reminder that pollution in one country can affect the environment in another.


10. Bosnia/Herzegovina

The Air Up There

(Photo via Indiawest/Flickr)

Sarajevo, the largest city and capital of Bosnia/Herzegovina, is the only European city on the WHO’s list of most polluted cities. With a PM10 of 110, it is ranked 50th, along with Abu Dhabi in the United Arab Emirates. While car exhaust is often noted as a cause, coal-power plants and industry are also significant factors.

A review of the factories in Bosnia/Herzegovina makes all too clear why the country suffers from serious air pollution: these include thermal power plants; cement factories; an acetylene, chlorine, and chloric acid factory; fertilizer plants and facilities to produce steel. All of these produce exhaust as well as plenty of industrial waste — but  a 2011 report notes that none of the country’s 122 wastewater plants were in operation.

Honorary Mention: United States – Bakersfield and Los Angeles

A Polluted Sunset.

(Photo of the sun setting through the smog of Bakersfield via andy castro/Flickr)

No U.S. cities are anywhere near the top of the WHO’s list of those that are most polluted. Some of the smoggiest cities in the U.S. are in California, as it is the most populous state and one in which the car is king.

Located on the southern edge of the San Joaquin Valley with mountains on three sides and in an oil-producing region, Bakersfield has the worst short-term and year-round particle pollution in the U.S. according to the American Lung Association’s State of the Air 2013 report (pdf). The city’s PM is 28 and the WHO ranks it as the 276th most polluted city in the world.

Los Angeles is listed as having the worst ozone pollution in the U.S. according to the State of the Air 2013 report (pdf). Over the 14 years in which the report has been issued, Los Angeles has had “noteworthy success” in cleaning up pollution; its ozone pollution rate has fallen 36 percent since 2000 and the city had “only” 125 days when the ozone was unhealthy last year. With an average PM10 of 25, Los Angeles is in a four-way tie with Pittsburgh, San Diego and Santa Ana/Anaheim for the position of the 467th most polluted cities on the planet.

As the WHO states, “exposure to air pollutants is largely beyond the control of individuals and requires action by public authorities at the national, regional and even international levels.” It’s all the more important for us to clamor and campaign for sustainable energy solutions from using far less coal to more bike lanes, so we can all breathe a little easier.

Photo from Thinkstock

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Lis T.
Elisabeth T.1 years ago

Thanks for the article....and pictures!

Kim Janik
Kim Janik1 years ago

As a Canadian, I'm glad we didn't make the list!

Jeannet Bertelink


Nimue Pendragon
Nimue Pendragon2 years ago

Cairo used to have the highest incidence of lung cancer in the world, don't know if that's still true. The pollution is bad and every person smokes, so what do they expect?

Kathy Perez
Kathy Johnson2 years ago


Carrie-Anne Brown

thanks for sharing :)

B A Robinson
BA R.2 years ago

just reading it is making me cough

Peta Clarke
Peta Clarke2 years ago

Pollution of the air such a unhealthy environment to live in. So glad I have no experience of it, feel sad for the people that have chest problems.

B A Robinson
BA R.2 years ago

I would have thought China would be # 1

Lisa Zilli
Lisa Zilli2 years ago

Good thing the U.S. has laws to reduce smog.