The worst figure was reported at Johan Setia in Klang, Selangor, with a 24-hour average air pollutant index reading of 151 at 3pm, while Kuching, Sarawak, recorded 110 and Tanjong Malim, Perak, 101.

Moderate air quality was reported in 60 areas.

The environment department said the worsening air quality in the three areas was due to transboundary haze.

The Asean haze centre reported scattered hotspots in Kalimantan while isolated hotspots were detected mostly in Sumatra, Sabah and Sarawak, with slight to moderate localised smoke plumes from hotspots in Sarawak and Kalimantan.

However, the full extent of the hotspots and smoke haze situation in the region could not be determined because of extensive cloud cover.

The air quality data from the environment department represents an average of readings taken over 24 hours and updated hourly. An index figure of below 50 indicates good air quality, 51-100 moderate, 101-200 unhealthy, 201-300 very unhealthy, and above 300 hazardous.