The haze in Tanjung Malim, Perak worsened this evening, recording an unhealthy Air Pollution Index (API) of 119 as at 5pm.
The API reading reached 100 at 4pm, compared to only 72 an hour earlier.
This is the only area in the country which recorded an unhealthy level out of the 52 API reading stations.
The second highest reading was in Cheras (97), Kuala Lumpur.
The other four areas in the Klang Valley approaching the unhealthy level of 100 are Batu Muda, Federal Territory (96), Putrajaya (93), Shah Alam (93) and Petaling Jaya (91).
In general, the API reading showed the northern cities recording better air quality, with Kangar at 23 as at 5pm, while Seberang Jaya 2 at 48.
In the southern part, the API reading for Nilai worsened slightly from 79 at noon to 89 as at 5pm, while Pasir Gudang recorded 89 at press time.
Air quality is considered unhealthy at the reading from 101 to 200.