According to the World Health Organization (WHO), some of the latest global air quality statistics revealed that more than 80% of people living in urban areas that monitor air quality are exposed to levels that exceed WHO recommendations. These levels are calculated by counting particulate matter (PM), or particulates, which are microscopic solids or liquids that cannot be seen by the naked eye. These tiny inhalable particles are then divided into categories, two major ones being PM 10 and PM 2.5 – the first being coarse particulates that have a diameter between 2.5 and 10 micrometres (μm), and the second being fine particulates with a diameter of 2.5 μm or less – these are common in smoke, soot and dust.
The size of these particles is a major factor when it comes to determining how dangerous they are when inhaled. The larger matter can be filtered upon entering the nose and mouth by mucus and cilia, but particles smaller than 10 micrometres can pose a much more serious threat. How? Well, they can evade these biological barriers, and settle in the deepest parts of the lungs, which can lead to serious health issues.
As well as being linked to obvious conditions such as asthma, lung cancer and cardiovascular disease, these particulates can also have a detrimental effect on fertility, pregnancy and lifespan. Unsurprisingly, PM levels are dangerously high in areas that are highly polluted, and many countries across the globe still have a very long way to go when it comes to battling emissions. Both the World Health Organization and the Environmental Protection Agency have both issues recommended PM limits, but some of the most polluted cities are 20 times that. Here are ten of the most polluted places on earth according to WHO – you might be surprised by some of them.
10
NIGERIA
Kaduna
Annual Mean: 90 μg/m3 of PM 2.5
Warning Type: Severe
Located in north-western Nigeria, Kaduna is both a trade centre and transportation hub that has witnessed rapid urbanisation over the last ten tears – something that can lead to an array of problems, including inadequate infrastructure, congestion, poverty and of course, pollution.
Year: 2013
9
QATAR
Doha
Annual Mean: 93 μg/m3 of PM 2.5
Warning Type: Severe
Qatar is known to many as a hub for building and construction, which is likely to be a key reason behind the country’s serious air pollution problem.
Year: 2012
8
UGANDA
Kampala
Annual Mean: 104 μg/m3 of PM 2.5
Warning Type: Severe
While Uganda is renowned for its abundant wildlife and stunning landscapes, it is also home to something much uglier. According to researchers, vehicle emissions are responsible for the majority of the pollution in Uganda.
Year: 2013
7
BANGLADESH
Narayanganj
Annual Mean: 106 μg/m3 of PM 2.5
Warning Type: Severe
A 2014 report conducted by the World Health Organization found that Bangladesh was extremely polluted, with the South Asian country home to high levels of gaseous pollutants, as well as dust particles. The city of Narayanganj is also home to a busy brick manufacturing industry, which speaks for itself.
Year: 2014
6
PAKISTAN
Peshawar
Annual Mean: 111 μg/m3 of PM 2.5
Warning Type: Severe
Towards the end of last year, Peshawar in Pakistan was displaying critical air pollution levels – and it wasn’t down to one factor. Vehicle emissions, construction, dust, poor-quality roadworks and fumes from burning waste are all to blame for the country’s polluted air.
Year: 2010
5
CHINA
Xingtai
Annual Mean: 128 μg/m3 of PM 2.5
Warning Type: Severe
Xingtai is renowned for its coal – more specifically, its coal-burning factories. The city is heavily polluted due to its huge industrial presence.
Year: 2014
4
CAMEROON
Bamenda
Annual Mean: 132 μg/m3 of PM 2.5
Warning Type: Severe
A combination of rapid urbanization and soil erosion is most likely to blame for the poor air quality in Cameroon, Africa.
Year: 2012
3
SAUDI ARABIA
Riyadh
Annual Mean: 156 μg/m3 of PM 2.5
Warning Type: Severe
Riyadh isn’t just Saudi Arabia’s largest city – it’s also its most polluted. Previous WHO reports have declared sandstorms, traffic and industrial waste as the culprits behind the majority of the pollutants in Saudi’s air.
Year: 2014
2
INDIA
City: Gwalior
Annual Mean: 176 μg/m3 of PM 2.5
Warning Type: Severe
Just under 200 miles away from a previous winner of the “Most Polluted City” competition, Delhi, lies a major Indian city known as Gwalior. While pollution from vehicles is a factor to take into consideration, the emissions don’t stop there. An increased use of fossil fuels is another reason for the dangerously unhealthy air, and buildings that aren’t energy efficient could also be to blame.
Year: 2012
1
IRAN
City: Zabol
Annual Mean: 217 μg/m3 of PM 2.5
Warning Type: Severe
Earlier this year, a study published in the Preventive Medicine journal declared that 30 minutes of cycling in the heavily polluted city of Zabol, Iran, would do the individual more harm than good. Named by the World Health Organization as the most polluted city on earth in 2016, Zabol is renowned in the region for its 120-day wind – a relentless summer dust storm that sweeps the area from north to south.
Year: 2012
The data featured in this article was taken from the World Health Organization’s 2016 ‘Ambient (outdoor) air pollution database, by country and city’ spreadsheet.
Image by vecstock on Freepik.
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