A NEW Pollutant Standards Index (PSI), to kick in from May, will expose the country's less-than-ideal air quality.
Under this new, higher standard, more days will be deemed "moderate" and fewer days deemed "good". This is because the new PSI will be expanded and is expected to be largely based on the prevalence of tiny and more hazardous pollutants called PM2.5 in the air.
PM2.5 refers to particulate matter up to 2.5 micrometers or microns in size. These particles are known to cause inflammatory responses both in the respiratory tract and blood vessels. Previously, the incidence of PM2.5 was not directly taken into account when determining the index.
Such particles generally come from activities that burn fossil fuels.
Nanyang Technological University's Professor Ang Peng Hwa was one of several experts who said that if "moderate" air quality becomes the norm here, pressure will be put on local polluters to improve their standards.
That norm would tell people that "at least some of this poor air quality is domestically generated, for example from urban traffic, and not all from fires in Indonesia. That could signal the Government to act on this," he said.
HOW does Singapore's air quality compare with other cities?
Some experts such as National University of Singapore's (NUS) Assistant Professor Jason Cohen, who is studying how climate change and haze interact, said the level of air pollution in Singapore during non-haze periods is common in many cities. Even haze such as that seen this year is also not unusual.
Other researchers found that during 2007, Singapore's annual PM2.5 level was sandwiched between those of Los Angeles, Tokyo and London, which were better, and Hong Kong, Berlin and Mexico City.
Prof Cohen said, however, that Singapore's annual average may disguise peaks and troughs caused by seasonal monsoon, rain and fires, while other cities such as New York may have more consistent levels throughout the year.
In 2010, a United States-based air pollution research body, the Health Effects Institute, released a report showing that pollution in major Asian cities exceeded World Health Organisation (WHO) standards.
Like other cities, in recent years, Singapore's air quality standards have fallen below WHO guidelines for three other city-related pollutants - sulphur dioxide, ozone and PM10 (particulate matter up to 10 microns in diameter.