Environment director Sharifah Zakiah Syed Sahab said the factory, which makes plywood out of oil palm tree trunks, had been burning the waste from the wood-making process.

Sharifah said the open burning of this waste led to a fire over a two-acre area adjacent to the factory at Jalan Changkat Mukim 11.

The factory was issued 10 compound notices for poor waste management and 10 for open burning.

The fire burned out of control since 12pm yesterday. She said firemen from Nibong Tebal Fire Station created a fire break to stem the fire from spreading further. Thermal drones had been flown to assist with fire extinguishing efforts.

“As for now, the fire is under control. But this comes at a time when Penang has not received any rain for the past nine days. It has contributed further to the decrease in air quality around Nibong Tebal,” she said in a statement.

She said the general smog and lower air quality over the past few days was from other sources.

“While the air quality remains at moderate levels, we want to remind all to not carry out open burning as it would only worsen air quality,” she said.

Sharifah said the Nibong Tebal fires caused heavy smog within the township compounding the haze brought from outside.

She said the efforts by the firefighting team from Nibong Tebal had led to an improvement in the air pollutant index to the mid-80s level as of 6pm. The effort will be continued tomorrow with thermal drones deployed to accurately detect smouldering sites.

Yesterday, the director-general of the environment, Wan Abdul Latiff Wan Jaffar, said three hotspots had been detected in Sarawak and one each in Perak and Pahang. He said in Indonesian Borneo, 97 hotspots were recorded in Kalimantan and Sumatra.