Sarawak's capital, Kuching has joined Tangkak in Johor and Bandaraya Melaka in the "very unhealthy" air quality category as of 3pm.

According to the Department of Environment's tracking of the Air Pollutant Index (API), Tangkak registered an API reading of 258, followed by Bandaraya Melaka at 220 and Kuching at 204.

A further 26 stations recorded "unhealthy" readings. There is a total of 68 stations nationwide.

The areas that were hardest hit are Sarawak and the southern states and west coast of Peninsula Malaysia, tallying with recent hotspot figures indicating that the source of the haze could be forest fires from the Indonesian regions of Kalimantan and Sumatra.

An API of 0-50 represents good air quality, 51-100 is moderate, 101-200 is unhealthy, 201-300 is very unhealthy, while 300 and above is hazardous.

This comes as the Asean Specialised Meteorological Centre (ASMC) showing intensified hotspots in Kalimantan, Indonesia.

According to the ASMC, as of yesterday, there were 411 hot spots in Kalimantan and 301 in Sumatra, 1 in Sabah and Sarawak and one in Peninsular Malaysia.

ASMC’s tracking has shown that the haze in Peninsular Malaysia is coming from Sumatra while the haze in Sabah and Sarawak is coming from Kalimantan.