|Vehicles are seen on the highway in Singapore, on June 19, 2013. The transboundary haze as a result of bush burning in neighboring Indonesia pushed Singapore's three-hour pollutant standards index (PSI) to an unprecedented " hazardous" level on Wednesday evening. (Xinhua/Then Chih Wey)
SINGAPORE, June 19 (Xinhua) -- The transboundary haze as a result of bush burning in neighboring Indonesia pushed Singapore's three-hour pollutant standards index (PSI) to an unprecedented " hazardous" level on Wednesday evening.
The three-hour PSI soared to 290 at 9:00 p.m., before climbing further to 321 at 10:00 p.m.
A reading above 100 means that the air quality is "unhealthy," and a reading above 200 is "very unhealthy." It is considered " hazardous" if the reading hits 300.
The previous worst smog reading was 226 in 1997.
The index has stayed above 100 most of the time since Monday, when the haze started to visibly affect the air quality and shroud the landmarks in the city state. The haze was largely a result of fire used to burn bushes on Sumatra so that the lands can be utilized for agricultural purposes.
Singapore Prime Minister Lee Hsien Loong said Singapore authorities have voiced their concerns with Indonesia and urged its neighbor to take tougher actions to reduce the haze.
Singapore's National Environment Agency said the haze has been affecting Singapore since June 13. It had advised children, the elderly and those with heart or lung diseases to avoid outdoor activities. Others are also advised to limit prolonged or heavy outdoor activities.
The hazy conditions are expected to persist for a few days, it said.
The sale of masks has been on the rise in Singapore, and some of the schools have cut short outdoor activities. Local supermarket chain NTUC FairPrice issued face masks to all of its pump attendants at its petrol stations.
Singapore's Environment Minister Vivian Balakrishnan said earlier on Wednesday that Singaporeans are "very frustrated, angry and distressed about the situation."
Indonesia has tough laws against bush burning but has problems with the enforcement of the laws, he said.