The haze today forced the cancellation of 10 flights scheduled to arrive and depart the Penang International Airport, said airport senior manager Arif Jaafar.

He said in a statement that the cancelled flights were two from Langkawi, six from Kuala Lumpur and two to Kuala Lumpur.

As at 4pm, four flights to and from Medan, Indonesia, were delayed, he said.

According to the Department of Environment portal, as of 6 pm, all areas in Penang recorded unhealthy Air Pollutant Index readings, with the reading being 172 at Universiti Sains Malaysia, 170 at Seberang Jaya 2 and 140 at Perai.

An API reading of 0 to 50 indicates good air quality; 51 to 100, moderate; 101 to 200, unhealthy; 201 to 300, very unhealthy and 300 and above, hazardous.