People choked as the air quality in the Klang Valley, Malacca, Negeri Sembilan and parts of Sarawak deteriorated.
Kuala Lumpur, Putrajaya and nearly all of Selangor were covered in thick haze, with a rapid rise in Air Pollutant Index (API) readings.
Areas worst hit are Pelabuhan Kelang (229), Shah Alam (243) and Batu Muda, Kuala Lumpur (224).
Malacca, Negri Sembilan, Perak and Sarawak continue to suffer unhealthy readings while Johor levels have dropped back to moderate levels.
An API reading of 0 to 50 indicates good air quality; 51 to 100, moderate; 101 to 200, unhealthy; 201 to 300, very unhealthy and 300 and above, hazardous.