Doctors are seeing a sharp rise in the number of patients suffering from haze-related ailments as Singapore was blanketed with smoke yesterday.
The medical conditions include upper respiratory tract infections, irritation to the nose, eyes and throat, and allergies of the nose and skin.
The Shenton Medical Group said its GP clinics are getting 15 per cent more patients while Raffles Medical's GP clinics are getting 10 per cent to 20 per cent more.
Doctors who The Straits Times spoke to say the haze appears to affect people of all ages, from young children to the elderly.
Dr Tan Tze Lee, a general practitioner in private practice, said he is seeing slightly more seniors affected.
He said he has treated 20 per cent more patients this week, but most had "minor to moderate irritation" and the situation is not as bad as it was in 2013, when the quality of air crossed the "hazardous" level.
The 24-hour PSI reading was between 132 and 148 at 11pm. The three-hour PSI then was 207, in the very unhealthy range.
This is higher than last year's 24-hour peak of 107 to 125 seen in October.
A PSI value within 101 to 200 is considered unhealthy.
Doctors are warning patients with chronic heart or respiratory problems to avoid going outdoors or exerting themselves. They should also see a doctor if they feel unwell, and not wait till their condition gets worse.
According to the American Cancer Society, deaths from lung cancer and heart attacks also increase as the air worsens.
Dr Koh Hau Tek, medical director for Parkway Shenton which runs the 20 Shenton Medical clinics, said many patients his doctors have been seeing had "underlying respiratory conditions" such as asthma.
The chain's clinics are preparing for more cases if the haze persists over the next few weeks, he added.
"I would advise the public, especially those with chronic heart or lung disease, to minimise outdoor exposure if possible and seek medical attention if feeling unwell."
Dr Michael Lee, Raffles Medical's deputy medical director, advised asthmatic patients to stay indoors, preferably in air-conditioned rooms or rooms with air purifiers.
If they have to go outdoors, they should carry their medicine with them in case of an attack.