Malls, restaurants, hawker stalls and tourist attractions are bracing themselves for smaller crowds as the haze bites on what should have been a typically busy June holiday weekend.
Business had already been slow all week, said the Singapore Retail Association, which estimated an 8per cent to 12per cent dip so far.
Shops in town areas say the situation is far worse, and is likely to deteriorate further - even with the ongoing Great Singapore Sale.
"Despite our end-of-season sale, which was launched last weekend, we have seen a 60per cent drop in customer footfall," said Mr Stan Lee, director at Swagger boutique on Ann Siang Road.
Restaurants are faring no better, especially those with outdoor seating. At Dempsey Hill, reservations at Jumbo Seafood are down by as much as 40per cent.
"Customers have been calling to change outdoor reservations to indoors. If that option is not available, they cancel their reservations," said Mr Shaun Chan, marketing manager for the Jumbo Group of restaurants.
Some have even removed al-fresco seating entirely. "For now, no one is allowed to go to the rooftop," said supervisor Shah Rul of Kinki Restaurant and Bar, which overlooks Marina Bay.
Hawkers are also suffering. At the Toa Payoh Lorong8 food centre, stallholders reported thinner crowds in the evening. Diners who braved the smog said they were finishing their food quickly or having it packed for home.
Business had dipped by up to 50per cent for some stalls. "The air is bad, and the smoke from our woks doesn't help," said Mr Wu Cai Xing, a helper at Good Luck BBQ Chicken Wings.
On the flip side, online stores and food delivery services are reporting better business.
But on the tourism front, attractions have drawn fewer visitors - or shut down altogether. Resorts World Sentosa closed three of its outdoor attractions yesterday, while Wildlife Reserves Singapore suspended all shows and activities at its parks yesterday.
Association of Singapore Attractions chairman Kevin Cheong warned that revenue will slide sharply if the haze does not subside in the coming weeks.
The Singapore Tourism Board said yesterday that "it is premature to determine the extent of the impact of the haze on tourist arrivals and revenue".
But Barclays Research noted that Singapore's tourism arrivals fell by 15per cent during the 1997 haze, and by 6per cent when the smog last hit in 2006. This year's slide in revenue is likely to fall between those figures, it said.
Professor Euston Quah, head of economics at Nanyang Technological University, calculated that the 1997 haze cost Singapore up to $268.3million in tourism receipts. This year's figure could be higher due to the higher PSI.
Hotels and travel agents said there were few cancellations so far, but there were ominous signs at the Marina Bay Sands SkyPark, which was almost empty during sundown. The few tourists who braved the open air retreated indoors quickly.
Said Japanese visitor Toshiaki Tominga, 34: "I wanted to stay for a shot of the sunset, but I think I won't any more."
Additional reporting by Lim Min Zhang