Cable Car 1890's Saloon, a bar in Cuppage Terrace off Orchard Road, is used to serving a full house by 7pm, even on Mondays.

But since the Orchard Road smoking ban kicked in on Jan 1, the strip of bars where Cable Car sits has been worryingly empty.

"There's almost a 40 per cent drop in business, it's crazy," the bar's manager, Mr Nick Pheh, told The Sunday Times.

His is not the only outlet feeling the squeeze. Acid Bar, Muddy Murphy's, Brewerkz and The Coffee Bean & Tea Leaf have also reported similar dips in patronage.

Anyone caught lighting up outside designated smoking areas (DSAs) risks a composition fine of $200, or the maximum court fine of up to $1,000.

The move to ban smoking in Orchard Road was aimed at protecting the non-smoking public from second-hand smoke, and is also part of national efforts to promote a smoke-free lifestyle.

The National Environment Agency (NEA) issued a daily average of 30 tickets for smoking outside of DSAs in the No Smoking Zone between April 1 and April 15, which followed a three-month advisory period.

An employee of Muddy Murphy's who declined to be named said that he has seen almost a quarter of his customers disappear.

"Our customers have all moved to Clarke Quay, and people who used to come here almost every day are gone," he said. "Drinking and smoking go hand in hand."

The nearest DSA from Muddy Murphy's is about 100m away.

Some smokers, however, remain undeterred by the ban. Ms Sarah Chia, 33, has frequently seen groups of smokers in the alley outside No. 5 Emerald Hill Cocktail Bar, a place she claims is an "unofficial smoking area".

"I do feel sorry for these smokers, especially those who work in Orchard Road," said the information technology specialist.

However, student Jega Thiagu, 20, said the ban has led to fewer cigarette butts littering the streets.

Despite the business slowdown, many pubs are not planning to raise the prices of their drinks to make up for the shortfall.

"It's not a smart move," said Mr Pheh. "And it won't fix the problem, which is that our customers want to smoke."

Smoker Ashley Soo, 19, an information and communications student, said finding a DSA is inconvenient.

"It's often secluded and difficult to find," she added.

Unless they can attract customers back, bars in Orchard Road may soon be in peril.

"There's no choice, we just have to deal with it," said Mr Pheh. An option was to build an indoor smoking room, but he felt it would be impractical.

NEA rules stipulate that indoor smoking rooms cannot take up more than 10 per cent of an outlet's area, and need to have separate ventilation and air-conditioning systems, which can cost up to $15,000.

Mr Pheh added: "We might have to shut down, who knows."