From 2005 to 2018, a global team of scientists used space-based measurements from instruments onboard NASA and European Space Agency (ESA) satellites to try to fill data gaps in air quality for 46 prospective megacities in Africa, Asia, and the Middle East.
The authors discovered significant annual increases in pollutants directly hazardous to the health of up to 14% for nitrogen dioxide (NO2) and up to 8% for fine particles (PM2.5) across all cities, as well as significant annual increases in PM2.5 precursors of up to 12% for ammonia and up to 11% for reactive volatile organic compounds.
The 'Airpocalypse'
The scientists blamed the rapid deterioration of air quality on rising industry and residential sources, such as road traffic, trash burning, and increased use of charcoal and fuelwood.
"Open burning of biomass for land clearance and agricultural waste disposal has overwhelmingly dominated air pollution in the tropics in the past, but our analysis suggests we're entering a new era of air pollution in these cities, with some cities experiencing rates of degradation in a year that other cities experience in a decade," said lead author Dr. Karn Vohra (UCL Geography), who took part in the study as a Ph.D. student at the University of Birmingham, as per ScienceDaily.
According to the report, the overall total number of people dying earlier as a result of elevated pollution grew the highest in cities in South Asia, notably Dhaka, Bangladesh (population 24,000) and Mumbai, Bangalore, Kolkata, Hyderabad, Chennai, Surat, Pune, and Ahmedabad in India (totaling 100,000 people).
According to the researchers, while the number of deaths in African tropical cities is currently lower as a result of improvements made in healthcare across the continent, which has resulted in a decrease in overall premature mortality, the worst impacts of air pollution on health will most likely occur in the coming decades.
Nine of the world's ten cities with the worst air pollution are in India, because of a microscopic particle called PM2.5.
According to a new WHO database released today, Ahmedabad is at the top of the list, with Delhi coming in third.
The top 10 list of the worst areas for a bigger but still dangerous pollutant, PM10, is more diversified, including settlements in Bahrain, India, Iran, Iraq, Pakistan, South Africa, and Saudi Arabia.
Both pollutants are produced by a combination of fossil fuel combustion in automobiles and power plants, as well as agriculture and natural sources such as desert sand.
Chinese cities, which once topped rankings of the world's most polluted cities, have significantly improved their air quality, as per NewScientist.
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Health Consequences of air pollution to people
It increases the risk of respiratory ailments, heart disease, and lung cancer.
Air pollution has been related to detrimental health consequences in both short and long-term exposures.
People who are already sick, such as children, the elderly, and the destitute, are more vulnerable to the effects.
Fine PM2.5 particles, which penetrate deep into the pulmonary airways, are the most health-damaging pollutants.
Particulate matter is produced in large amounts by sources such as diesel automobiles and coal-fired power plants.
PM2.5 particles (particles with a diameter less than 2.5 micrometers) are known as "fine" particles, and they pose the greatest health danger.
Fine particles can lodge deeply in the lungs due to their tiny size (about 1/30th the breadth of human hair).
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