The World Health Organization (WHO) stipulates a maximum breathable \u201csafe limit<\/a>\u201d of 15 micrograms per cubic metre of PM2.5 across a 24-hour average. In haze affected parts of Indonesia, this year\u2019s concentrations have routinely exceeded 500 micrograms, and even 1,000 in places \u2013 that\u2019s more than 65 times the WHO maximum.<\/p>\n This is not the kind of polluted air you might find on a smoggy day in most parts of the world \u2013 it is a toxic atmosphere considered by the US Environmental Protection Agency to be \u201chazardous\u201d<\/a>. The delayed effects of breathing such air include increased risk of heart attack, stroke and a host of respiratory illnesses<\/a>. <\/p>\n The catalyst for this year\u2019s crisis is a collision between meteorological events and decades of changes to Indonesia\u2019s landscape. The historically intense El Ni\u00f1o has brought a punishing dry spell<\/a> across the archipelago, leaving the landscape parched. <\/p>\n But the weather is only the match; land management practices provide the fuel. <\/p>\n Historically, lowland tropical forests growing on peat soils were naturally resistant to fire because of their moist conditions. However, deforestation for agriculture<\/a>, forest fragmentation and peatland drainage have drastically altered the landscape and increased its flammability<\/a>. <\/p>\n The effects can extend beyond the areas directly cleared or drained: even untouched forest close to degraded areas will have lost some of its natural fire resistance<\/a>. The El Ni\u00f1o-driven drought has supercharged these changes, making it easier for fires to take hold and spread.<\/p>\n Fire is widely used across the region, to help prepare land for agriculture, clear low-lying vegetation, or to burn household waste. Yet, when fires are set during a drought, they can ignite the drained peatland soil and escape into the surrounding landscape. <\/p>\n A peat fire does not simply flame and pass; it also smoulders downwards into the ground, sometimes burning for weeks or months. An alarming consequence of peat fires is the release of ancient carbon\u2014organic matter that has been safely locked away for hundreds of years<\/a>. This carbon generally won\u2019t be reabsorbed by future forest growth, as the land has been repurposed for agriculture. It is a permanent transfer of carbon from land into the air. <\/p>\n This year alone, Indonesia\u2019s fires have released an estimated 175 million tonnes of carbon<\/a>, equivalent to three-quarters of the country\u2019s annual fossil-fuel CO\u2082 emissions and exceeding the combined annual fossil-fuel and industrial CO\u2082 emissions of the UK and France<\/a>.<\/p>\n The scale of the 2026 fire and haze marks a setback after some years of progress. There has been a promising downward trend<\/a> in regional fire activity, due in part to improved fire management<\/a> and efforts at \u201cre-wetting\u201d peatlands to make them less flammable. <\/p>\n The severity of the current El Ni\u00f1o has interrupted this good work. Satellite analysis indicates more than 120,000 fire hotspot detections across Indonesia so far \u2013 fewer than in 2015 (another El Ni\u00f1o year), but seven times as many as in 2025.<\/p>\n The human and economic cost<\/a> of the resulting haze is staggering, and many will likely perish from the effects of the toxic smoke. The haze has also drifted beyond Indonesia, at times blanketing neighbouring Malaysia, Brunei, southern Thailand and Singapore. <\/p>\n The health effects of wildfire smoke extend around the world. Globally, exposure contributes to a million or more premature deaths each year, including almost one in ten deaths<\/a> of children under five. <\/p>\n Worryingly, the number of fires in Indonesia could actually be underestimated as satellites are less effective at detecting the lower temperatures of smouldering peat fires. New technologies designed to better detect these fires<\/a> could help authorities identify them sooner and respond more quickly, provided the data can be rapidly delivered to those who need it. <\/p>\nThe roots of the crisis<\/h2>\n
The hidden cost of peat fires<\/h2>\n
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\n Martin Wooster<\/span><\/span>
\n <\/figcaption><\/figure>\n![\"Firefighters](\"https:\/\/images.theconversation.com\/files\/768592\/original\/file-20261027-62-et48a0.jpg?ixlib=rb-4.1.1&q=45&auto=format&w=754&fit=clip\")
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\n Martin Wooster<\/span><\/span>
\n <\/figcaption><\/figure>\nFrom detection to prevention<\/h2>\n
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