The Impact of Air Quality on Our Brain Health

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Australia ranks among the best in the world for air quality, but with worsening climate change and an ever-extending bushfire season, some experts warn even low levels of air pollution are impacting our health.

As more and more evidence links air pollution to both long and short-term cognitive issues, medical experts say in the long term.

It’s not just our lungs at risk

One key indicator of air quality is the density of what is known as particulate matter, or PM, which refers to a mixture of solid and liquid droplets found in the air.

When small enough, these particles can get deep into our lungs.

But while we often associate air pollution with lung health, evidence suggests our brains are also at risk.

Rachel Tham, a research fellow in environmental epidemiology at the University of Melbourne, said: “When they [PM] enter the brain, they set off an inflammatory reaction in the brain, which then over time can lead to the changes in brain structure.”

“There’s much more research being done about understanding that long-term exposure with things like Parkinson’s disease and .”

Air pollution is one of the greatest environmental risk factors to public health globally, and it’s even said to be the greatest external threat to human life worldwide.

The World Health Organization estimates the combined effects of ambient pollution and household air pollution causes around seven million premature deaths every year.

Elaine Luthi, UNICEF’s regional chief of advocacy and communication for East Asia and the Pacific, said air pollution in the region is disproportionately impacting children.

Australia ranks high, but researcher warns against complacency

Bangladesh, Pakistan, and , according to the 2023 IQ Air World Air Quality Report.

Out of the 134 countries ranked, from worst to best, Australia sits comfortably at number 128.

But that doesn’t mean we are immune.

A study recently published in the journal Nature Communications found even brief exposure to air pollution can impact a person’s ability to focus on everyday tasks.

With higher air pollution in more industrial areas, Tham said people in lower socioeconomic areas are often at greater risk.

She said in addition to older adults and those with weakened immune systems, pregnant women and children are among the most vulnerable to air pollution.

Experts say, in addition to older adults and immunocompromised persons, pregnant women and children are among the most vulnerable to air pollution. Source: AAP

“We’ve also done research that’s looked at children’s cognitive function at schools and measured by the NAPLAN [National Assessment Program for Literacy and Numeracy] scores,” Tham said.

“And we found across Australia that children that were in schools that were in lower socioeconomic areas closer to major roads, there was a trend towards lower NAPLAN scores. So there could be some academic impacts as well for children.”

Studies conducted in the United States and Denmark have also shown links between exposure to traffic-related pollution and lower cognitive functioning and academic performance.

Could polluted air be a dementia risk factor?

Though research is still being done in the area, some studies also suggest prolonged exposure to polluted air is a risk factor for dementia.

When air quality is bad, our body triggers its immune defences, said Fay Johnston, a public health physician, environmental epidemiologist and lead investigator at the Centre for Safe Air.

She said even low-level air pollution can, over time, have an impact on our health.

“If air quality is chronically a little bit bad, then those reactions will be going on in the background, but they’re small compared to all the other things that shape your health and your brain health, like diet, like exercise, like your genetic makeup,” she said.

“So it’s one of many things that affects overall health and wellbeing, and through that mechanism, it can make you more likely to develop sorts of diseases like heart disease.

“But in the brain over time, over many years, it’s a higher risk of dementia or a higher risk of getting a stroke.”

Calls for change

Outdoors, things like traffic fumes and dust storms create low-level pollution in the air, whereas inside, gas appliances and indoor wood fires also pose a risk.

The Centre for Safe Air estimates wood heater smoke in Australia is linked to between 558 and 1555 earlier-than-expected deaths each year.

“We’ve got more than a million wood heaters,” Johnston said. “They’re very inefficient; they make a lot of pollution for the amount of energy they give you compared to, say, a diesel engine.”

Johnston believes better policy is needed to reduce what she said is a “chronic source of pollution”.

When we think of climate change-related deaths, it’s the immediate and direct fatalities caused by natural disasters that often come to mind.

During the Black Summer bushfires five years ago, air pollution in and around the affected areas caused air quality to drop to levels far worse than what’s regarded as hazardous.

A report from the Grattan Institute estimated the pollution from those fires sent around 2,000 people to hospitals with respiratory problems.

The bushfire smoke alone was responsible for 417 deaths that summer.

Johnston said as the frequency of bushfires increases, we may start seeing longer-term impacts on health.

“The longer it goes on for, all the accumulation over the years is much more important for your health than a single smoky day,” she said.

“If a bushfire smoke episode is bad and goes on for a week or so, then in people who are at higher risk … years later, the slight impacts are still measurable.”

In the longer term, air pollution in Australia and around the world is continuously worsened by the burning of fossil fuels.

Experts suggest that, at an individual level, using face masks, HEPA air filters, and more active methods of transportation like walking and cycling can all help reduce our exposure to air pollution.

But Johnston said one of the most effective ways to avoid worsening air quality is to have a better policy around climate action.

“That’s the overwhelming main message.

“But then very specifically for air pollution, there’s lots of other kinds of policies that can help us promoting active transport, public transport to reduce the use of cars, promoting electric vehicles.”