It is best known for being located along the snow-capped mountains of the Himalayas.
But despite the awe-inspiring scenery, Nepal is actually the most polluted country in the world.
According to Oxford University’s Our World in Data platform, residents of the landlocked country in South Asia are exposed to 99.73 micrograms per cubic meter (μg) of particulate matter (PM2.5) on average throughout the year.
Experts called the figure – which is almost 20 times higher than the World Health Organization’s guideline values of 5 μg/m3 – “alarming”.
By comparison, levels in the UK were 10.47 μg/m3, while the US recorded 7.41 μg/m3. It means the nations had the 24th and ninth cleanest air, respectively.
It is measured in particulate matter 2.5 (PM2.5) and can be particularly dangerous – it has been linked to worsening medical conditions such as heart disease
PM2.5 refers to tiny particles less than 2.5 micrometers in diameter — about one ten-thousandth of an inch.
The particles can contain dust, soot, metals and other chemicals. This pollution is linked to the burning of fossil fuels and is released from car engines and factories.
Because the particles are so small, they pose a major health risk as they can be inhaled deep into the lungs. Plenty of evidence shows that long-term exposure increases the risk of serious illness and death from cardiovascular and respiratory diseases.
Air pollutants not only harm the heart and lungs, but also affect the brain, and studies link exposure to a higher risk of dementia and cognitive decline.
The World Health Organization (WHO) states that the annual average concentrations of PM2.5 should not exceed 5 µg/m3.
The air quality data, collected in 2017 and based purely on levels of PM2.5, is available for 195 countries.
After Nepal, Niger (94.05 μg/m3) and Qatar (91.19 μg/m3) had the highest concentration of PM2.5.
The researchers said the high concentrations in North Africa are “very high,” in part because of “drier conditions with more sand and dust sources.”
Rounding out the top five countries with the worst air quality is India, where its population of 1.4 billion was exposed to 90.87 μg/m3 of PM2.5, and Saudi Arabia, where 87.95 μg/m3 was recorded.
With the exception of Qatar, PM2.5 levels of each of the top five countries had risen since 1990 – indicating that efforts to improve pollution levels have been unsuccessful in some countries.
Of the top five offenders, Nepal had the biggest jump in PM2.5 levels, rising 12.13μg/m3. This jump is more than double the average annual exposure to PM2.5 in Finland.
Egypt (87μg/m3), Cameroon (72.79μg/m3), Nigeria (71.80μg/m3), Bahrain (70.82μg/m3) and Chad (66.03μg/m3) were also among the countries with the worst air quality.
Dr. Raj Tiwari, an assistant professor of climate change data science at the University of Hertfordshire, told MailOnline: ‘Countries such as Nepal (South Asia), Niger (Africa) and Qatar (Middle East) are at the top for PM2.5, with an exposure greater than 90 – which is very alarming.
At the other end of the scale, Finland recorded the lowest mean annual exposure to PM2.5 (5.86 µg/m3). However, this figure is still above WHO safety levels.
It was closely followed by Brunei, a small country bordering Malaysia, which was exposed to just 5.9 μg/m3.
New Zealand (5.96 μg/m3), Sweden (6.18 μg/m3), Canada (6.43 μg/m3) and Iceland (6.48 μg/m3) also recorded low levels of the air pollutant.
It may come as a surprise that the country with the highest death rate is not Nepal, but in fact Uzbekistan
Pollution is one of the world’s biggest health problems, as it was the cause of 6.67 million global deaths in 2019, making it the world’s third leading cause of death
The Our World in Data figures also revealed national death rates from outdoor air pollution in 2019.
Despite Nepal recording the worst levels of PM2.5, it was Uzbekistan that recorded the highest death rate.
The Central Asian country, home to 20.5 million people, reported 179 deaths per 100,000 people — more than double the 81 in 1990.
It is closely followed by Egypt, where the death rate was 161, and Qatar (133).
Dr. Tiwari said: ‘Further analysis of the death rates due to outdoor air pollution is really eye-opening as it clearly shows how air pollution is strongly linked to the economies of the countries.’
According to the UN, poorer countries tend to have weaker air pollution laws, lower vehicle emission standards and more coal-fired power plants.
Meanwhile, Finland recorded just three deaths per 100,000 caused by pollution exposure – the lowest in the world.
Pollution is one of the world’s biggest health problems, after 6.67 million deaths worldwide in 2019, making it the third leading cause of death according to WHO.
In 2019, according to a Global Burden of Disease study published in The Lancet, high blood pressure ranked first for the world’s leading cause of death (10.85 million), closely followed by smoking (7.69 million).