Indonesia's Riau province, the second closest to Singapore, has the worst haze in 2015 on Thursday as visibility level at the Sultan Syarif Kasim II airport in Pekanbaru fell to as low as 200m, the lowest so far this year, disrupting flights going to and leaving the provincial capital city.
A minimum visibility level for a plane to land is 1,000m. The airport saw visibility level fall to as low as 500m in morning hours on Wednesday. It is normally worse in the morning as the hazy skies are exacerbated by the fog.
Air quality has reached dangerous levels in parts of Riau province, including Panam area that saw this year's record low Poluttant Standard Index of of 436, or hazardous level.
Six of the 14 districts and cities in Riau had a hazardous PSI level, indicated as the black colour. Pekanbaru had a PSI level of 282 on Thursday (red colour). PSI levels run from good, moderate, unhealthy, very unhealthy (red), and hazardous (black).
"Riau will only see the rainy season in October or November. Riau is so badly hit because it gets the haze from fire from within its own province, plus from Jambi and South Sumatra province," Mr Sugarin, head of meteorological office at the Pekanbaru airport, told The Straits Times by telephone.
