The air quality in Singapore and parts of Malaysia has worsened, reducing visibility and disrupting flights in East Malaysia as the smoke haze from forest fires in the region thickened.

The air pollutant index reached "unhealthy" levels in Sabah and Sarawak states, located on the Malaysian part of Borneo island. In Singapore, the haze from fires in Indonesia obscured the sunlight, lowered temperatures and reduced visibility in the island-nation. Air quality in Singapore on Monday was the worst recorded this year, said the National Environment Agency. Its Web site has updates on the pollution: http://app.nea.gov.sg/psi/ Smoke from forest fires in Malaysia and Indonesia cloud the region annually during the dry season from around July to October as farmers clear land for cultivation by setting fire to trees and bushes. The worst occurred in 1997 and 1998, when a widespread, thick haze caused economic losses of almost $9 billion in Southeast Asia as travelers shunned the region and health-care costs increased.