People pass the skyline of Singapore's central business district shrouded by haze August 26, 2016. REUTERS/Edgar Su(reuters_tickers)
By Marius Zaharia
SINGAPORE (Reuters) - Air pollution in Singapore rose to the "unhealthy" level on Friday as acrid smoke drifted over the island from fires on Indonesia's Sumatra island, the city-state's National Environment Agency (NEA) said, in a repeat of an annual crisis.
Every dry season, smoke from fires set to clear land for palm oil and pulp and paper plantations in Indonesia clouds the skies over much of the region, raising concern about public health and worrying tourist operators and airlines.
The 24-hour Pollution Standards Index (PSI), which the NEA uses as a benchmark, rose as high as 105 in the afternoon. A level above 100 is considered "unhealthy".
The NEA said it planned a "daily haze advisory" as "a burning smell and slight haze were experienced over many areas" in Singapore.
Indonesia repeatedly vows to stop the fires but each year they return. This year, Indonesia has arrested 454 people in connection with the smoke pollution.
When heavy, the choking smog closes airports and schools and prompts warnings to residents to stay indoors.
Pollution levels in neighbouring Malaysia were normal on Friday.
Singapore has pushed Indonesia for information on companies suspected of causing pollution, some of which are listed on Singapore's stock exchange.
A forest campaigner for the environmental group Greenpeace Indonesia, Yuyun Indradi, said the government was struggling to enforce laws to prevent the drainage of peatland for plantations and the setting of fires to clear land.
"It has become a challenge for the government to enforce accountability among concession holders, to enforce its directives on blocking canals, and push companies to take part in efforts to restore peatland and prevent fires," Indradi said.
"Now is the time for the government to answer this challenge. It is in the law."
Greenpeace said, according to its satellite information, there were 138 fires across Indonesia on Friday.
(Reporting by Marius Zaharia, Fathin Ungku and JAKARTA bureau; Editing by Robert Birsel and Nick Macfie)