Prof Fredolin Tangang of Universiti Kebangsaan Malaysia’s (UKM) Centre for Earth Sciences and Environment said Southeast Asia is experiencing hot spells and rising temperatures, causing peat fires to spread easily.

“In Malaysia as well as in Indonesia, peat land can be a problem during prolonged drought. It catches fire easily. Once it catches fire, it is difficult to put the fire out,” he told FMT when asked about the dry season and the haze affecting Malaysians.

The Air Pollutant Index (API) in the peninsula increased this week, with major towns in several states reaching unhealthy levels.

Kuala Lumpur recorded an API reading of 157 today, Petaling Jaya 140, Shah Alam 130 and Klang at 118. Seremban in Negeri Sembilan recorded an API of 118.

The worst affected area was Rompin, Pahang, which recorded a reading of 194, close to “very unhealthy”.

An API below 50 is rated good, 51 to 100 moderate, 101 to 200 unhealthy, 201 to 300 very unhealthy, and 301 and upwards hazardous.

Fredolin said the dry spells in Malaysia and neighbouring Indonesia were caused by the Central Pacific El Nino and the Indian Ocean Dipole (IOD), a phenomenon similar to El Nino.

The IOD is an irregular oscillation which causes ocean surface temperatures to rise in certain parts of the ocean, occurring once in several years.

“But research shows that with climate change, it may happen more frequently. It may be a norm to have dry spells during this time,” he said, cautioning that this would easily trigger peat fires.

Fires are typically set across Indonesia to clear land, often carbon-rich peat forests, to make way for plantations.

Haze from West Kalimantan was detected crossing into Malaysian Borneo on Sept 5, according to Indonesia’s weather agency.

But the Indonesian government has refuted claims that the recent rise in hotspots in Indonesia has resulted in transboundary haze.

The haze from the 2015 fires in Indonesia stoked a diplomatic row between Indonesia and Singapore and Malaysia.