Johor haze likely linked to smoke from southern Sumatra

The Johor haze, a thick haze blanketing the southern part of Malaysia, is likely being exacerbated by smoke originating from fires in southern Sumatra, Indonesia. Prevailing winds have been carrying this transboundary smoke across the Malacca Strait and into southern Peninsular Malaysia. The Asean Specialised Meteorological Centre (ASMC) has reported moderate to dense smoke plumes emanating from hotspot clusters in southern Sumatra, with haze from the region also moving towards Singapore and southern Peninsular Malaysia.

The ASMC, which monitors weather, climate, and haze across the region, assesses the risk of transboundary haze based on factors like hotspot activity, smoke density, rainfall, and wind patterns. Recent heavy rain in Johor has slightly improved air quality, with Air Pollutant Index (API) readings dropping at several monitoring stations.

However, as of 4pm, four out of Johor's eight air-quality monitoring stations still recorded "unhealthy" readings. Kota Tinggi led the list with an API of 159, followed by Pasir Gudang at 161, Pengerang at 158, and Larkin at 152. Tangkak, Batu Pahat, and Kluang remained in the moderate range at 62, 72, and 68, respectively.

Singapore's National Environment Agency (NEA) has also noted smoke plumes from southern Sumatra, with prevailing winds forecast to blow from the southeast or southwest. Last month, Malaysian Meteorological Department Director-General Dr Mohd Hisham Mohd Anip stated that the haze is expected to persist as long as open fires continue in Sumatra and Kalimantan during the Southwest Monsoon.

He attributed the smoke contributing to the haze to fires in Sumatra, with the consistent Southwest Monsoon winds carrying the smoke towards Malaysia.