Panic buying swept Beijing during the "airmaggedon," as residents turned to what they saw as their only possible saviors - air purifiers and face masks.

Outside the IQAir corporate office near the US embassy, a Chinese secretary tried to fit four washing machine-sized units into her boss's Mercedes-Benz sedan. Parents spooked by news reports about choking smog contacted Torana Air Center owner Chris Buckley from overseas to order masks and air purifiers for their children spending a semester studying in Beijing.

Both IQAir and Torana had record sales days, selling out their entire inventories. Buckley's well-heeled and usually polite customers were arguing about who was in line for service first.

"I wished I'd trained my staff in counseling," says Buckley, who studied chemistry at Oxford in the UK. "We had some customers who were very agitated when you tell them you haven't got replacement filters for their children."

Record smog, record sales

The recent wave of severe smog peaked on January 13, when the air quality index hit 886, according to US embassy monitoring. The measure of various pollutants in the air was 17 times higher than the level considered "good" and almost triple the level considered "hazardous."

Buckley says he received a few extra calls that day, but not very many. "I think some people looked at the reading and couldn't believe it," he said.

However, the next day his two shops - in the CBD's swanky Central Park apartment complex and expat suburban haven Shunyi district - were flooded with customers, who had cleaned out his entire inventory by January 16.

"On Tuesday [January 15], we were just taking orders. The next shipment came on Friday [January 18], and we pre-sold two-thirds of that," he said.

Customers also swarmed the headquarters of IQAir, a much larger air purifier maker with seven stores in Beijing and a branch office in Shanghai.

Counting the cost of clean air

While most of Buckley's customers are expats, Swiss giant IQAir gets most of its business from multinational corporations, embassies and affluent Chinese. Air purifiers from Torana and IQAir cost more than 3,000 yuan ($482) and 10,000 yuan respectively for the smallest units, a luxury to most families.

The BBC purchased six units alone. The woman who tried to squeeze four units into her Mercedes gave up, requiring her boss's driver to ferry three purifiers home and her to follow with the final unit in a taxi.

"On Monday, our receptionist literally couldn't hear herself think, there was so much chatter," says IQAir CEO Mike Murphy.

IQAir saleswoman Christina Wang stepped in over the weekend to help manage the company's Chinese-language Sina Weibo account, which was inundated with inquiries, partly because of recommendations from customers with thousands of followers, she said.

"More and more Chinese people have satisfied their basic needs. They have an apartment and enough to eat. Now, they are worried about their health," she said.

Sensing the impending rush, Wang came into the corporate headquarters early on Monday to make sure her customers were among the first to receive their orders, including a Chinese mother with asthma who wanted an air purifier because she did not want to take medication while nursing her newborn.

Murphy expects the city's worsening smog will lead to a flood of new sales to corporations, schools and embassies seeking to calm the health concerns of jittery staff and customers.

Doomsday hype misplaced

Buckley appreciates the extra business, but wishes people would take a calmer view of the dangers of air pollution. "This wasn't something that was going to kill them immediately," he said of the smog. "For most people, the effect of the 'airpocalypse' was the equivalent of a few nights in a night club and a few drags of a friend's cigarette."

As for the media's dramatization of smog by using terms such as "airpocalypse," Buckley believes it is "one of the least helpful things in the press."

"It's no use for me to say air pollution should be reported in a calm and reasonable manner without plays on words because it's never going to happen," he says.

The health risks of air pollution are cumulative over years, he said, citing data that suggested living in a city like Beijing for 10 years could take eight months off your life on average.

"First of all, it should not stop you from coming to Beijing," he says. People can rationally manage the risk by choosing to live far from main roads, wearing masks in traffic and, on bad air days, staying indoors with air purifiers at home, work or school, he says.

In the four years since starting the company, Buckley had never received an e-mail from a concerned parent of an overseas student. But over the past two weeks, he has received four.

He told one parent: "The air pollution problem here is serious, but it is a long-term thing. If your daughter is fit and well with no bronchial problems, she will be OK here. We will tell her about masks and air purifiers."

Torana and IQAir have since replenished their stock, but with an apparent "second coming" of the so-called airpocalypse on the horizon, sales remain high.

Both expats and ex-Beijingers have long cited pollution as a top reason for leaving the city, but Murphy thinks the latest wave of choking air could deliver the nail in the coffin for many families.

"This was the final decision for people to move on to greener pastures and bluer skies," says Murphy.  "One of my son's teachers came in [to the store]. After two-and-a-half years, they said they are leaving due to the smog."

Murphy started the business with his wife six years ago. The business has since grown to 78 people and his product is now being carried by a Chinese electronics chain in other cities.

But the recent record-breaking smog has made even Murphy's Chinese wife push for his family to move to his adopted home of Vancouver, Canada.

"The kids are sick. [My wife] is sick. She's afraid to have them outside," he says. "Her main question is, 'which is more important: the kids' health or the success of the business?'"

As a father, Murphy says he wants to move. But as a businessman, his instincts tell him to stay. "I can't sell air cleaners in Vancouver," he quipped.