Right now, people in parts of Indonesia are inhaling what may be the most polluted atmosphere on Earth. As the historically large 2026 El Niño intensifies, parts of south east Asia have been plunged into an air quality crisis of catastrophic proportions.

Smoke from fires has driven concentrations of dangerous and tiny particulate matter, known as PM2.5, to extreme levels – creating a public health emergency threatening millions of lives.

The World Health Organization (WHO) stipulates a maximum breathable “safe limit” of 15 micrograms per cubic metre of PM2.5 across a 24-hour average. In haze affected parts of Indonesia, this year’s concentrations have routinely exceeded 500 micrograms, and even 1,000 in places – that’s more than 65 times the WHO maximum.

This is not the kind of polluted air you might find on a smoggy day in most parts of the world – it is a toxic atmosphere considered by the US Environmental Protection Agency to be “hazardous”. The delayed effects of breathing such air include increased risk of heart attack, stroke and a host of respiratory illnesses.

The roots of the crisis

The catalyst for this year’s crisis is a collision between meteorological events and decades of changes to Indonesia’s........

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