Visibility was down to a few hundred metres and government officials yesterday described the air quality over parts of Sumatra island as "dangerous," as up to 500 brush fires raged out of control. In Pekanbaru, the capital of Riau province on central Sumatra, a dark grey cloud hung low over the city and many people stayed indoors rather than breathe the polluted air. "The level of air pollution in Pekanbaru is dangerous," said Teuku Alamsyah, a senior local government official. "It is hazardous and could cause lung infections and other health problems."