Via The Star :
" Air quality deteriorated rapidly overnight with Muar in Johor hitting hazardous levels for the first time with an Air Pollutant Index (API) reading of above 380, according to the Department of Environment (DOE).
This is the first time in years that air quality has dipped to hazardous level with conditions worsening in as dry weather persists and fires rage in Sumatra.
At 7am, the API was at 337 but it deteriorated to 383 just several hours later at 11am Thursday. A good API reading is from 0-50, moderate (51-100), unhealthy (101-200), very unhealthy (201-299) and hazardous (300 and above).
The air quality also worsened in Kota Tinggi which now records very unhealthy levels with an API of 232 as of 11am while Pasir Gudang had an API reading of 199.
As of 5pm Wednesday, seven areas recorded unhealthy, 39 moderate and five good air quality readings, but there were no very unhealthy or hazardous readings.
Aqua satellite images show 376 hotspots over Sumatra while the NOAA satellite shows 173 hotspots, with cloud cover preventing precise readings.
According to the Asean Specialised Meteorological Centre, scattered hotspots with localised smoke plumes were detected mainly in central Sumatra."