SINGAPORE (Sept 28): Singapore schools reopened on Monday after pollution from Indonesian forest fires led to their closure on Friday, while Malaysia said it will shut some education institutions as the air quality worsen in areas near Kuala Lumpur.

The three-hour pollutant standards index in Singapore stood at 115 at 6am in the "unhealthy range" on Monday, after the city-state got some respite with the air quality in the moderate for most of the weekend. The measure had climbed to the year’s high of 341 on Friday morning, entering the hazardous level for the first time. A reading exceeding 300 is classified as “hazardous”.

In addition to shutting its grade and high schools, the city-state also suspended some outdoor events on Friday as smoke from the forest fires shrouded the city-state with a layer of haze. A prolonged period of high pollution levels would hurt its economy, said Vishnu Varathan, a Singapore-based economist at Mizuho Bank.

“So far, the impact on the economy is not significant as the haze didn’t last long,” Varathan said. “That would change if we had higher levels of air pollution for three weeks or longer.”

Singapore residents are expected to adjust their plans for now, heading to the malls instead of outdoor activities, he said. If it lasts longer, people may choose to stay home, which will dent industries such as transportation and entertainment, he said.

Malaysia ordered some schools to close as the air quality in areas surrounding Kuala Lumpur worsened to “very unhealthy” levels over the weekend. The Air Pollutant Index stood between 154 and 195 in the "unhealthy range" for eight districts near the capital as of 5am Monday, according to data on the Malaysian Department of Environment website. Schools in Kuala Lumpur, Putrajaya, Selangor, Negeri Sembilan and two areas in Sarawak were asked to shut on Monday, the education ministry said in an e-mailed statement.

Smoke from Indonesian forest fires has blanketed Southeast Asia with a layer of haze in the past few weeks. Data compiled by Global Forest Watch showed a concentration of fires in parts of Indonesia’s Sumatra and Kalimantan, driving the air quality of cities located in the areas to hazardous levels.

The effects of the haze depends on wind direction, with the weather pattern playing a role in pollution levels, said Gabriel Lau, an earth system science professor at the Chinese University of Hong Kong.

Singapore also named four Indonesian companies that it says may have contributed to the fires and said it would apply more pressure on palm oil and forestry companies responsible for the burning.