The Australian Bushfires Could Be Far Deadlier Than We First Thought

Harbour Bridge

The kind of smoke haze that’s been smothering Sydney for weeks isn’t just bad for your lungs, it can get into your brain and cause Alzheimer’s like symptoms, according to a US study.

Published in the journal Brain, the study looked at air pollution classed as PM2.5, the very kind that’s been causing the smoke haze over Sydney. PM.2.5 refers to very fine atmospheric particulate matter (PM) which is less than 2.5 micrometers thick, or about 3% the thickness of a human hair.

When in the air, PM2.5 reduces visibility and creates the hazy effect. You’ll probably see it now if you look out the window today anywhere in Sydney and parts of NSW and Queensland.

We already know that PM2.5 easily penetrates the lungs and bloodstream and can trigger asthma, bronchitis and other respiratory problems, but the US study has discovered that PM2.5 doesn’t stop there.

Changes to the brain

The researchers from the University of Southern California have found it can make changes to the brain’s structure that resemble those of Alzheimer’s disease and various dementias.

The researchers used magnetic resonance imaging to look at the brains of 998 women aged 73 to 87, matching air pollution data to their residential addresses. The scans showed that increased exposure to PM2.5 over 11 years was associated with distinct Alzheimer’s like changes to the brain that included memory problems and even the atrophying of brain tissues.

The amount we breathe

The level of PM2.5 in the air is measured in micrograms per cubic metre. In Australia, the standard of eight micrograms per cubic metre is one of the world’s strictest, but during the bushfires, it rose as high as 734 micrograms in some of the worst affected suburbs. That was the same as the amount of smoke per square metre that would be produced if you smoked 37 cigarettes.

This study is not the only one to link air pollution to the brain. Two more recent studies have pointed to the awful truth that air pollution isn’t just responsible for global warming and respiratory problems, its damage to human health is far worse than expected.

It raises risk of brain cancer

A Canadian study has linked particles from car and truck exhausts to brain cancer for the first time. Published in the journal Epidemiology, the study found that an increase in exposure to ultra-fine particles (UFPs) that are largely found in diesel exhaust, dramatically increases the risk of brain cancer, a rare but deadly form of the disease. The analysis revealed that an increase in exposure to UFPs that was the equivalent of moving from a quiet street to a busy road for a year, increased the risk of brain cancer by 10 percent.

It raises risk of stroke

Long term exposure to traffic exhaust near people’s homes raises the  risk of stroke, according to a Swedish study, which blames a fine particle air pollutant called black carbon, a sooty material produced by cars and coal-fired power plants. The researchers used data from 114,758 people in three Swedish cities, 3,119 of whom experienced strokes. The researchers found that the risk of stroke went up by 4 percent for every additional 0.3 micrograms per cubic meter of black carbon pollution from traffic exhaust.

The get-out-of-jail card produced by industry and governments for air pollution is always that while occasional high levels are bad as in the bush fires the exposure is only short term and should not result in any serious long-term effects.

But with research increasingly revealing air pollution’s more hidden deadly dangers, even short-term exposure could soon become unacceptable to most of us.