Having spent six years in Dalian, Nina has considered leaving Beijing and returning to the port, not only because of the air pollution in the capital. Other factors would also influence her decision. "I like the arts environment here in Beijing and I have experienced a lot of great culture here. However, if I wanted to retire or opt for an easier life, I would definitely return to Dalian," she said.

Doubts linger over warning system for smog

Beijing sees little improvement in air quality in 2013

"There's too much pressure in Beijing - the air quality, the flow of people and the lifestyle," she said. "When I first moved to Beijing, for the first six months I was completely alone without a circle of close friends."

An attractive destination

China is becoming increasingly attractive as a destination for immigrants, with the speed of economic development and the relatively low cost of living cited by many as the main reasons.

In some places, it's still possible to set up your own business without too much stress, according to Pym. His wife has opened a caf in Dali, something she couldn't imagine doing in Shanghai, given that rents and other living costs are so high there.

If anything were to make them consider leaving China, it would be their son's education, rather than the level of pollution, according to Pym. Their son will be fine until he reaches high-school age, but unless a school with high educational standards opens in Dali in the next few years, the family will probably have to leave.

But should circumstances force them to move, Pym has no idea where they would go next. As an illustrator for several publishing houses and magazines, he could return to the UK, but equally he could move elsewhere.

"But like I said, it's years till we have to make a decision, and hopefully we will be able to stay," he said.

Top 10 cities with best air quality inChina	China's top 10 richest cities