BBC: At the age of 13, Tan Yi Han could not see the edge of his schoolyard. It was 1998 in Singapore, the wealthy city-state known for its tidy streets and clean, green image. But for much of that particular school year, clouds of smoke shrouded the skyline. The record-setting air pollution, which had begun in 1997 and lasted for months, caused a 30% spike in hospital visits. It would later be remembered as one of South East Asia's worst-ever "haze episodes'.
Haze episodes have occurred in South East...