Concerns over air pollution are being raised as Beijing announced its co-bid for the 2022 Winter Olympics with Zhangjiakou, a city in its neighboring Hebei province.

The capital's ambition to host another Olympic Games draws public attentions to the smog issue, which has always been the most debated topic in Beijing during the past several years. Despite its success in 2008, people worry that Beijing's the deteriorating environment would make the IOC think twice before giving it a second chance.

"Clean air is necessary for hosting the Olympics and it is urgent that the government to take it seriously," one person said on the Sina Weibo, a twitter-like social website in China.

Besides the air concerns, another problem Beijing faces is the routine that two successive Olympics cannot be held in the same continent. As Pyeongchang, South Korea, will host the 2018 Winter Games and Tokyo will stage the 2020 Summer Olympics, the chance for Beijing's 2022 Winter Olympics may seem slim.

Though so many uncertainties will be addressed, Olympics still remains appealing to China.

"Olympic Games will bring a comprehensive improvement to both the hardware and international consciousness of a city. The bidding process itself is an opportunity for us to have a deep understanding of the Olympic spirit," said Wang Ning, former director in the operating center of Beijing 2008 Olympics' opening and closing ceremonies.