Southeast Asian haze

The Southeast Asian haze is a recurring, fire related transboundary air pollution problem across the region, driven mainly by the burning of biomass and worsening between roughly July and October, particularly during El Nino years. Its primary cause is large scale slash and burn land clearing for agriculture, especially oil palm and pulpwood plantations, since burning is far cheaper than mechanical clearing. Fires on peatland make the haze considerably worse, because dry peat is high in carbon and sulfur and produces dense, toxic smoke when it burns.