2006 Southeast Asian haze

The 2006 Southeast Asian haze was an air pollution event caused by continuous, uncontrolled burning from slash-and-burn agriculture in Indonesia, which affected several countries in the Southeast Asian region and beyond, including Malaysia, Singapore, southern Thailand, and as far away as Saipan; the effects of the haze may have even spread to South Korea. Local sources of industrial pollution also, inadvertently, contributed to increases in air toxicity (particularly in already-polluted areas); notably at-risk areas included communities close to textile factories, fertilizer plants, meat-packing plants, industrialised dairy farms, shipping ports, and oil refineries.

Source: Wikipedia — 2006 Southeast Asian haze (CC BY-SA 4.0)