The public have been told to wear masks while outdoors as the state is expected to be hit by prolonged hazy conditions.
The advice came from state environment committee chairman Phee Boon Poh.
"The haze is here to stay as we are approaching the inter-monsoon period before the north-east monsoon starts in October.
"We have been monitoring the situation and over the past three days, the Air Pollutant Index (API) readings were between 75 and 88.
"The readings on the island are always higher than the mainland.
"Although it may still be below the critical level, we appeal to the people to avoid strenuous exercise, especially in urban areas.
"If you want to exercise, it will be better to go to parks such as the Penang Botanic Gardens or the Penang City Park," he said.
A check with the Environment Department website at 1pm yesterday showed that the readings in Seberang Prai, Seberang Jaya, Balik Pulau and Minden were hovering between 78 and 90.
An API reading of between 0 and 50 is good while 51 to 100 is moderate, 101 to 200 is unhealthy, 201 to 300 very unhealthy, while anything beyond 300 is deemed hazardous.
Yesterday, the haze which came close to unhealthy levels blanketed several parts of George Town, with the Penang Bridge barely visible from a distance.
Phee said there were also higher than the normal cases of cough and flu reported in the state.
"It is important to drink more warm water during such weather," he said.
However, there were no flight delays at the Penang International Airport (PIA) as visibility level was up to 5km.
PIA senior manager Mohd Nadzim Hashim said the haze was not as bad in terms of visibility standards.
"We only ground aircraft if visibility is below 800m," he said.