The unhealthy Air Pollutant Index (API) in several areas of Sarawak will be closely monitored from time to time said Prime Minister Datuk Seri Najib Razak.

In his Twitter account and Facebook posting Thursday, Najib expressed concern over the unhealthy air quality in several areas.

"I am concerned with the haze situation in Sarawak and the unhealthy air quality in Kuching, Samarahan and Sri Aman," he said.

According to the Department of Environment (DOE), as of 5pm, the API in Sarikei was 104 compared with 99 at 1pm.

Three other areas that recorded unhealthy API are Samarahan (167), Sri Aman (154), and Kuching (146).