Singapore's national environment agency has warned the elderly, young or those with chronic lung conditions or heart disease to avoid prolonged or strenuous outdoor activity. Indonesia has in previous bouts of haze attempted to seed clouds, to create rain storms that can damp down fires and pollution.
The pollutant standards index measures six types of air pollutants including fine particulate matter which can be easily inhaled and cause breathing problems or asthma. At least 200 hotspots have been counted in Sumatra by Singapore's meteorological service with as many as 300 in Indonesian Borneo.
Last year the smog surpassed "hazardous" levels, forcing Indonesia's then president, Bambang Susilo Yudyhono, to apologise to Singapore and Malaysia. The haze was the worst since 1997-98, which was estimated to have cost Indonesia $9bn.
But she said: "It would be nice to have it go away for good. The annual burning of forest area in the region has been blamed but I do hope the authorities can do something about it before we lose our health."