My patients are telling me they are worried about how long this is going to last and how much higher this is going to go," he said.
In Indonesia's Riau province, where the fires are concentrated, the PSI reached 400 on Friday, the head of the local health office told the BBC.
Schools there are to remain closed until the air quality improves.
The chief of the health department Zainal Arifin said there was an "increasing number of asthma, lung, eye and skin problems due to higher CO2 levels".