the expats offering a breath of fresh air in polluted beijing - personal air purifier
Beijing is known for its terrible air, which is dangerous for people to breathe.
Earlier this month, the city recorded more than 20 times the World Health Organization's health level.
This is the most polluted day since global media reported Beijing's "air pollution" in January 2013.
The incident led to a small outflow of some foreigners and delayed some who wanted to go to the Chinese capital, which has a population of 20 million.
But for those who are aggressive enough, this is a very unlikely opportunity.
Chris Dobbing, 24, came to Beijing from Oxford in September 2012.
While working at an education company, he noticed respiratory problems with many local students.
"I found a mask on the Internet that I can recommend them to wear, but for children I started working with the US WOGG mask company to develop child masks and sell them in China, no Mr. Dobbin was found to say.
Moving to Beijing paved the way for the good, bad and ugly flag of China's best British people to leave Beijing for foreigners forced to leave Beijing, the Chinese returned from the West to Shanghai, with the policy of "foreigner-specific, he became a director of the wog mask China business and started his own business, developing a fashion awareness
Air pollution masks are designed to be cooler than regular masks.
Chris Dobbing saw 53-year-old Chris Buckley, from Poole, who developed mild asthma after he arrived in Beijing in 2000.
After doing the research, he discovered the problem and obtained a doctorate in physical chemistry, conducting his own testing of the air purifier manufacturer's claim.
He now has two stores in Beijing that sell air purifiers and other products, which he says makes him "much richer" than the company that previously sold Tibetan carpets ".
His website, toranacleanair.
It also contains information designed to alleviate concerns about air pollution.
Another successful British expat in this niche market is Paul Afshar.
After resigning from a successful PR job in London at the age of 26, he moved to Beijing in 2011 and set up a website, ijustwanaby.
Com, the original purpose was to be a foreigner
For online stores.
However, he quickly became involved in higher-margin air pollution products.
"In January 2013, our revenue and sales were higher than in the first eight months," said Mr Afshar, who broke the air pollution record in Beijing.
He noted that products sold by some Chinese retailers and manufacturers in the market were not protected by pollution.
Two years later, he sold the company to a larger operator in the market as revenue grew significantly.
While he won't reveal the exact numbers, he says he makes enough money out of sales to be able to make a "pretty, two-
Bedroom apartment in Shoreditch, London.
"These foreign entrepreneurs in China are a symbol of the incredible economic success of the Asian giant.
China's gross domestic product grew by about 2010 to 2012 in two years.
However, with this astonishing growth, environmental problems have become more serious.
Shanghai has seen smog problems recently, and smog problems in small cities such as Harbin may be more serious than in Beijing.
All three expats interviewed for the story predicted
The air pollution market will continue to grow.
For other entrepreneurs, however, smog is a long-term problem.
They were originally in terms of growing business.
Customized Beijing (bespoke-beijing. com)
It is a travel company that provides travel advice and services for tourists wishing to visit the historic capital.
Clients include celebrities like Rock Band killer and former band
Tyra Banks, model and TV host
Recently, pop singer Katy Perry also visited.
Sarah keenside of Essex said: "We are walking around, Katie and her manager said everything they have heard about Beijing is pollution . "
Founder of Beijing custom.
Miss Keenlyside, 32, was a reporter for The Times. In the months of 2013, bookings were significantly lower than in previous years, she said.
She blamed the results on the pollution scare.
"Our business is growing, but pollution is really a big part of it.
Negative impact on business", she said.
Hotels, international schools and multinational corporations were affected, with the number of tourists dropping by 10 in January to November 2013. Three years-on-
According to a report by the Beijing Municipal Tourism Development Commission.
The number of tourists dropped by 2.
By contrast, the proportion of China as a whole in 2013 was 5.
Although pollution affected Beijing's image abroad, especially as a tourist destination, Miss Keenlyside quickly pointed out the city's cultural and historical attractions.
She told potential visitors: "Don't worry unless you have a respiratory problem.
If you live here for many years, you will be affected and you will not be affected if you are here for a few days.
"She found that the air would not cause problems for her in a day --to-day basis.
"I have no reason to leave," she said . "
"There is so much to offer in Beijing that pollution should not define the city.
But when you can't see the sun and you can't see the sky, it does burn you out.
It's more of a psychological thing.