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Why the air in SA's cities could give you Alzheimer's


Why the air in SA's cities could give you Alzheimer's

Our air is packed with the microparticles that lead to the dreaded disease

Senior science reporter

What secrets does a dead body hold about the city where its owner lived, breathed and died?
In the case of 203 Mexicans – ranging from babies who hadn’t yet seen their first birthdays to adults up to the age of 40 – their cadavers have yielded a surprising finding that is relevant to people across the globe, including South Africa.
A study focusing on the autopsies of these 203 individuals showed that air pollution in big cities increases the risk and progression of Alzheimer’s – starting early in childhood. An incredible 99.5% of the subjects showed signs of the disease.
Dr Lilian Calderón-Garcidueñas, a researcher from the University of Montana, and her team believe the detrimental effects are caused by “tiny pollution particles that enter the brain through the nose, lungs and gastro-intestinal tract”.
These particles damage all barriers and travel everywhere in the body through the circulatory system and, according to the researchers, there are two abnormal proteins that indicate the development of the disease even in babies under one year of age.“Alzheimer’s disease hallmarks start in childhood in polluted environments, and we must implement effective preventative measures early.
“It is useless to take reactive actions decades later,” said Calderón-Garcidueñas, whose research was published in the Journal of Environmental Research.The really dangerous particles proven to have a link with Alzheimer’s are those known as PM2.5. The PM stands for particulate matter, and the 2.5 means the particles have a diameter of 2.5 micrometres.
That might be hard to conceptualise, but imagine this: each particle has a diameter that is only 3% the diameter of a human hair, and you need an electron microscope even to see them. That’s why the World Health Organisation calls PM2.5 the “invisible killer”.
So should South African city dwellers be worried? The answer is yes.
No city in our country comes close to Mexico City which is a heaving mass of 24 million people and has much higher general levels of air pollution.
However, according to international database company Numbeo, Johannesburg has double the PM2.5 levels of Mexico City, and Johannesburg is set to become a megacity (more than 10 million residents) by 2030.Already in Johannesburg, there are 41 micrograms of PM2.5 per square metre – that is 4.1 times the WHO guidelines, and twice the level in Mexico City.
The Megacity State, which is a report by international finance company Allianz, said that in 1950, New York and Tokyo were the only two megacities. By 2015, there were 29 (mainly in Asia), and many were already suffering from air pollution issues.
By 2030, there will be 41 and the already-polluted Johannesburg will be on the list.
In Cape Town, PM2.5 is at 16 and in Durban there are 14 micrograms of PM2.5 per square metre.
But interestingly, the real bad boys in South Africa are Pretoria and Hartebeespoort. The former has 51 micrograms per square metre (5.1 times the WHO guideline) while the latter has a staggering 60.
Both were listed among the worst 10 cities in Africa in terms of PM2.5.
Many of the other metropoles, such as Port Elizabeth and East London, were not tested.

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