SINGAPORE - The recent hazy conditions here are due to accumulated particle matter under light winds, according to the National Environment Agency (NEA).

NEA, which issues daily updates on the haze situation, first warned that Singapore may experience "slightly hazy conditions in the morning" last Tuesday (Oct 17).

Since then, haze-like conditions have been reported in certain areas over the past week. Photos taken by The Straits Times on Wednesday evening from the Marina Bay area showed hazy skies.

According to NEA, however, the likelihood of the country being affected by transboundary haze remains low.

"There were eight hot spots detected in southern Sumatra, and no visible smoke plume or haze was observed," NEA said in its last update on Wednesday.

The hourly concentration readings for PM2.5 - tiny pollutant particles associated with haze - for the next 24 hours are expected to stay in the normal range.

As of 9am on Thursday, the 24-hour Pollutant Standards Index (PSI) was in the moderate range.

Hazy conditions were also experienced in the first week of October, prompting fears that fires were once again burning in the region.

However, air-quality experts whom The Straits Times spoke to clarified that it was not transboundary haze. They instead attributed the conditions to the concentration of particle vapour and local emissions from cars and factories.

While such particles usually disperse on their own, cloudy conditions and little wind could have caused certain areas to appear hazy.