Sales of fireworks and firecrackers have slumped this Spring Festival, vendors say, as residents aim to avert the dense smog that engulfed the city in January.

"People just seem less enthusiastic than before," said An Fenglan, who runs a fireworks stall in Beijing.

"Those that are buying don't want big fireworks," An said. "The smaller ones are selling much better, but that means less money for us."

Zhou Zhengyu, deputy secretary-general of Beijing municipal government, said just 260,000 boxes of fireworks were sold throughout the capital from Feb 5 to 9, Lunar New Year's Eve. The figure is 37 percent down on the 410,000 cartons sold during the same period last year.

In a report by Beijing Times, a spokesman for Beijing Fireworks Co was quoted saying its sales had plunged 30 percent.

Pollution levels soared in many parts of North China last month, resulting in a haze that clouded cities for many days.

In the capital, the average density of PM2.5 — microscopic matter that can enter the lungs and blood stream — reached 180 micrograms per cubic meter in January, about 30 percent higher than the same period from 2009 to 2011, Xinhua News Agency reported.

According to Feng Kun at the Beijing Municipal Commission of City Administration and Environment, the bad air has drastically raised residents' environmental awareness.

Fireworks seller An agreed. "I do think this is what's behind the fall in sales," An said. "Many residents are exercising restraint to keep the smog at bay."

Chinese traditionally use fireworks and firecrackers to symbolically ward off evil spirits and bad luck.

However, Beijing resident Feng Jianbin said he is so concerned about pollution he has vowed not to set off a single firecracker this year.

"We have suffered too much from the filthy smog," the 54-year-old said.

"I know it's tradition but one of the few things we can do ourselves to reduce air pollution is to cut the fireworks."

Feng Yongfeng, founder of Green Beagle, an environmental protection NGO in Beijing, said cutting back on fireworks during the holiday is a great leap forward.

People have the option of buying smaller fireworks or those that give off less pollution if they really want to celebrate the festival in the old tradition, he said.

It is not just in Beijing that residents are attempting to kick the fireworks habit. Other cities have also seen sales plummet.

"I still have about half of my stock to sell," said Yun Tianzhi, who runs a fireworks stall selling fireworks in Shenyang, Liaoning province.

He estimated his earnings have dropped by 40 percent compared with last year.

"I'm not expecting much from the upcoming Lantern Festival," he said.

Yun said he used to sell thousands of yuan worth of fireworks each day, but the business is not as prosperous as it was.

Yun said he is considering quitting the business next year because of the gloomy market.