PETALING JAYA: The air quality at central and north peninsula hit unhealthy levels as haze covered the Federal Territories as well as states such as Penang, Perak and Negeri Sembilan on Friday (Sept 29).
The Air Pollutant Index (API) in Kuala Lumpur recorded an average of 154.5, with Cheras being affected the worst at 155 and Batu Muda at 153.
The API in Selangor showed an average API of 127.4, with Petaling Jaya affected the worst at 153 and Klang the least at 88.
The Meteorological Department considers unhealthy API levels to be between 101 to 200.
Some areas outside of the Klang Valley recorded API unhealthy levels as well. Putrajaya recorded an API of 117, Taiping, Perak at 131 and Seberang Jaya, Penang at 110.
Haze readings started to pick up gradually from 5am onwards.
The Asean Specialised Meteorological Centre (ASMC) said the haze was caused by smoke plumes over Sumatra blown north-west by prevailing winds.
"Under the prolonged dry weather, elevated hotspot activity and widespread hazy conditions are expected to persist over the fire-prone areas in southern and central Sumatra and southern Kalimantan.
"The prevailing winds are forecast to blow mainly from the south-east," it said.