Illegal forest clearing fires in Indonesia’s Sumatra Island are sending haze across the Malacca Strait to neighbouring Malaysia and Singapore, causing the worst air pollution since 2006. The haze prompted Malaysia to alert vessels in the Malacca Strait of poor visibility as short as two nautical miles and shut many schools. Singapore, covered in thick smoke last week, saw its three-hour Pollutant Standards Index recording rise to an “unhealthy” range of 108 as of 6 p.m. (1000 GMT), much higher than 80 on October 20, which was the worst since 2006. “The suspicion is that this is coming from forests that have been opened up for plantations. We think it may be for palm oil,” Purwasto Saroprayogi, head of the land and forest fires department at Indonesia’s Environment Ministry, was reported as saying.