Moving from a quiet to a busy street raises the risk of brain cancer by 10% due to air pollution, a study finds

Woman walking. (Photo: Getty Images)
Woman walking. (Photo: Getty Images)

From townhouses on bustling Cape Town avenues to apartment buildings on busy Johannesburg highways, thousands of South Africans live and work in big cities where toxic fumes and dust are inescapable, surrounding us in the air we breathe.

In recent years, mounting research has found this dirty air has consequences for our health, from aggravating respiratory conditions such as asthma to lowering our IQ.

Now, the teeny nanoparticles in polluted air have been linked to a higher risk of brain cancer.

These ultra-fine particles (UFPs) are produced by fuel burning, particularly in diesel vehicles, and higher exposures significantly increase people’s chances of developing the potentially fatal cancer.

The presence of toxic nanoparticles from air pollution in human brains was first observed in a study published in 2016 in the journal Proceedings of the National Academy of Sciences.

"Any time you burn anything, these small particles are produced," Scott Weichenthal, epidemiologist and co-author of a study published earlier this month, told UPI.

"These particles are so small they can get into our bloodstream and into our brains."

And once there, they can do significant damage, such as increasing our risk of developing brain cancer, Weichenthal tells the Guardian.

The team, from McGill University in Canada, performed their analysis using the medical records and pollution exposure of nearly two million adult Canadians from 1991 to 2016.

Published in the journal Epidemiology, their research found that a one-year increase in pollution exposure of 10 000 nanoparticles per cubic centimetre – the approximate difference between quiet and busy city streets – increased the risk of brain cancer by more than 10%.

Although brain cancers are rare, researchers calculated that an increase in pollution exposure roughly equivalent to moving from a quiet city street to a busy one leads to one extra case of brain cancer for every 100 000 people exposed.

“Environmental risks such as air pollution aren’t large in magnitude – their importance comes because everyone in the population is exposed,” says Weichenthal.

“So when you multiply these small risks by lots of people, all of sudden there can be lots of cases. In a large city, it could be a meaningful number, particularly given the fact that these tumours are often fatal.”

These areas have the worst air pollution in South Africa

Figures contained in a detailed air-quality report presented in parliament by the department of environmental affairs in September show the Vaal Triangle’s air to be the most polluted in the country, followed by the coalfields of the Mpumalanga highveld.

The third worst air quality can be found in and to the north of the Waterberg in Limpopo.

The quality of air was measured by 136 monitoring stations across the country, especially in identified priority areas and areas with dense low-income communities.

On top of the three worst areas referred to above, there were a number of towns and neighbourhoods where air pollution reached unacceptable levels at least once (and in some cases more often) in the last year, reports The South African.

The affected areas mentioned in the report were:

Western Cape

Bellville South

Cape Town Atlantic Seaboard

Cape Town City Bowl




Table View

Eastern Cape

Port Elizabeth-Walmer



Durban Central


Free State

Bloemfontein Central

North West












Springs Central





Sources: The Guardian, The South African, Epidemiology Journal


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