Nearly 50,000 people were suffering from respiratory problems linked to worsening haze from forest and brush fires on Indonesia's Sumatra island, an official said Tuesday.Pollution reached "extremely hazardous" levels in several districts of the island's central eastern province of Riau, dpa quoted spokesman for the National Disaster Management Agency Sutopo Nugroho as saying."The number of people who have become ill continues to increase," he said. Visibility was down to 200 meters in the provincial capital Pekanbaru early Tuesday, he added.Around 2,500 firefighters and soldiers were deployed while aircraft dropped water on the forest fires, he said. "Scattered blazes and lack of water are hampering efforts."The smog has also disrupted flights to and from Sultan Syarif Kasim airport in Pekanbaru, with dozens of cancellations since Sunday, officials said.Smoke from forest fires on Sumatra is an annual dry season hazard that often affects neighboring Malaysia, Singapore and Thailand.