Environment

Pacific Air Pollution Traced to Africa and Asia

Burning down forests in Africa and South-East Asia causes ozone pollution in the air as far as the western Pacific Ocean, researchers say, calling for revision of global climate models to reflect their findings.

In a paper published in Nature Communications last week (13 January), the scientists say their data contradicts earlier theories on the origins of ozone-rich air parcels above the tropical western Pacific, which were thought to descend naturally from a higher atmospheric layer.

Ozone, a greenhouse gas, occurs naturally in the atmosphere. But it is also created from the reactions of pollutants produced by combustion engines and burning trees to clear land for agriculture.

Flying in two research planes at two different heights, the scientists analysed the air composition over Guam, the largest island of Micronesia, in the western Pacific.

Using data and models on wind, rainfall and forest fires, the researchers found that the Guam skies contained a cocktail of chemicals, alongside ozone, similar to the signature chemicals from fire smoke in Africa and South-East Asia.

Thunderstorms and winds from South-East Asia could carry this polluted air high up to the atmosphere and far from its source in countries where deforestation is common, such as Indonesia - 3,750 kilometres away from Guam - and even those in tropical Africa.