We like to think that Australia has pristine skies, and to some extent this is true, but we are all exposed to near-invisible pollutants in the air around us.

And not only are these pollutants hard to see, but so are their impacts.

Air pollution makes significant global contributions to major killers like lung cancer, respiratory infections, stroke and heart disease, but it is often difficult to directly identify the culprit.

In fact, the 2015 Australian Burden of Disease Study attributes over 2,500 deaths per year in this country to dirty air.

The main causes are microscopic particles and gases formed in combustion, mostly burning coal for electricity, igniting diesel to move people and freight, and combusting wood for heating, in bushfires, as well as in controlled burns.

Many of our nearest neighbours and biggest trading partners are even less fortunate.

The World Health Organization (WHO) estimates that outdoor air pollution is responsible for 4.2 million premature deaths every year. These deaths are concentrated in China, India and Southeast Asia. In many parts of the world, air pollution is now one of the biggest public health concerns, and a handbrake on economic growth.

But there is a good news story here – air quality quickly improves once we cut pollution off at the source.

Since the 1970s, the United States, empowered by the Clean Air Act, has made consistent and lasting reductions in ambient levels of the worst air pollutants.

Similar improvements have been seen across Europe, and by imposing and enforcing tighter air quality and emissions standards many countries have realised enormous health benefits.

Moreover, independent analysis has found that the cost of improving air quality in the US has been offset by productivity gains and reduced healthcare burden at a staggering ratio of US$30 for every US$1 spent on air quality.

So, what more can Australia do to clear the air?

Most importantly, for the worst pollutants we need to tighten air quality standards – the levels at which we recognise and act on unhealthy air.

For the combustion products nitrogen dioxide (O₂) and sulfur dioxide (SO₂), and the toxic chemical ozone (O₃) that they subsequently make, Australia's Ambient Air Quality Measure sets levels of these pollutants that are substantially higher than the WHO recommends.

Most of our contemporaries, however, meet or in many cases exceed the WHO recommendations. Australia's environment ministers are meeting to reconsider these standards later this year, and action is expected.

Australia is a big country, and to provide clean air to all Australians we also need expanded monitoring networks that go well beyond the cities and affluent suburbs.

Satellite data has shown that some of the world's dirtiest power stations are found in Australia, including in Victoria's Latrobe Valley, and the residents in these traditionally economically disadvantaged areas are the ones exposed to their harmful emissions.

In Melbourne's West, dirty old diesel trucks can still be found hauling freight on residential roads, and air quality measures in these areas routinely track as worse than in the CBD.

As part of the Science Gallery Melbourne's DISPOSABLE exhibition and the White Night festival this year, we have the rare opportunity to safely sample air from some of the dirtiest cities in the world.

All clean air is alike; every megacity is polluted in its own way. Understanding these differences is at the core of the scientific effort to help solve their air pollution problems.

Visual artist Michael Pinsky's Pollution Pods simulate the effects of being exposed to air from London, New Delhi, São Paulo and Beijing, contrasting them to pristine Norwegian air.

Confined to interconnected domes, we have the chance to walk around the world, breathing in the worst it has to offer.

The Pollution Pods give us the opportunity to experience what it might be like to live with crippling air pollution day-in day-out. It should also give us pause to think about just how clean the air we breathe is, and how we can make it safer for everyone.

The Pollution Pods are at Melbourne's Treasury Gardens until Sunday 31st August as part of the White Night festival and Science Gallery.

Banner: Getty Images