Lan Yanfei, 34, moved away from Beijing to escape the heavy smog, vowing never to return for the sake of her children's health.

"I previously worked in Yangzhou, Jiangsu province, but in 2007 I got a job offer in Beijing. At that time, the whole country was excited about the Olympic Games in the capital. I really wanted to witness the event myself and progress in my career there," Lan said.

"Before I moved to Beijing, I only knew about possible sandstorms and dry weather. But fueled by my dreams, I didn't really care about environmental conditions."