Air quality in Singapore today could get worse than it was yesterday.

The National Environment Agency said yesterday evening that if more haze from Sumatra is blown in, the air quality in the next 24 hours could enter the middle of the unhealthy range.

Otherwise, it is expected to be between the high end of the moderate and low end of the unhealthy bands, similar to the conditions most of yesterday.

The forecast comes even as some outdoor eateries here were hit by slower business as customers stayed away because of the haze.

Across the Causeway, the worsening haze caused almost 1,500 schools to close. The two worst-hit states were Selangor and Sarawak.