PETALING JAYA, Sept 27 — Clearer skies were anticipated next month as the wind direction will again shift when Typhoon Dujuan makes landfall over eastern China on Tuesday, according to the Malaysian Meteorological Department (MetMalaysia).

Its spokesman Dr Hisham Mohd Anip said the typhoon is currently in northern Philippines, forcing winds to move towards its centre, carrying the haze from its source in southern Sumatra and southern Kalimantan to Malaysia.

“It is natural for the wind to follow the location of a typhoon and gravitate towards its low pressure area.

“Dujuan has disturbed that wind direction,” he said.

Hisham added wind patterns were never uniformed and that made it difficult to forecast which part of the country would be hit by the haze.

Commenting on the public’s confusion over poor visibility when the Air Pollutant Index (API) reading was low, Department of Environment (DoE) director-general Datuk Halimah Hassan said the criteria used by MetMalaysia to rate visibility differed from the criteria used by DoE to determine air quality.

“The API level is recorded on a 24-hour average, based on five main pollutant particles in the air, while the visibility index is measured based on instantaneous observation by MetMalaysia,” she said.

The API is updated every 24 hours, while the visibility index is done every hour. Hence, the contradiction.

Yesterday, Department of Civil Aviation (DCA) director of flight operations Datuk Yahaya Abdul Rahman said several inbound flights at Sultan Abdul Aziz Shah Airport in Subang had to be re-routed to alternate airfields, like the KL International Airport in Sepang.

He said several outbound flights were also cancelled after visibility fell below the approved range of 800m.

Yahaya, however, did not disclose the exact number of the delayed, cancelled and re-routed flights.

Malaysia Airports Holdings Berhad (MAHB) said it had not issued any directive to airlines to suspend their operations and services due to poor visibility.

“Firefly was the only airline that suspended its services,” said MAHB spokesman Ahmad Shahreen Rahim.

He said they were still waiting for DCA to issue further instructions regarding operating under such conditions.

At 6pm yesterday, seven areas recorded “unhealthy” API readings — Malacca (134), Bukit Rambai (104), Nilai (103), Port Dickson (108), Seremban (106), Balok Baru (129) and Indera Mahkota (110).

An API reading of zero to 50 is good, 51 to 100 moderate, 101 to 200 unhealthy, 201 to 300 very unhealthy and 301 and above is hazardous.

According to Asean Specialised Meteorological website yesterday, 93 hotspots were detected in Kalimantan, 41 in Sumatra and 18 in Sulawesi. One hotspot was detected in Kelantan.