Singapore enveloped in a thick cloud of wood smoke caused by forest fires in Sumatra . `` I can say it 's actually getting worse , '' a Singapore-based energy industry analyst who did not want to be named told CNN . Pollution Index reached 371 on Wednesday , the worst level since 1997 when it reached 226 . The Environment Agency says air quality becomes ' very unhealthy ' when the index passes 200 . Singapore is anxious to avoid a repeat of the 1997 haze crisis which cost an estimated $ 9 billion .
Singapore enveloped in a thick cloud of wood smoke caused by forest fires in Sumatra . Pollution Index reached 371 on Wednesday , the worst level since 1997 when it reached 226 . The Environment Agency says air quality becomes ' very unhealthy ' when the index passes 200 . Singapore is anxious to avoid a repeat of the 1997 haze crisis which cost an estimated $ 9 billion .