Yu Yingqi, 24, presses the happy face screen to express her good mood at a bus station in Wangfujing street, Beijing, on July 20. [Wang Jing / chinadaily.com.cn]

No unhappiness allowed! These days bus commuters in Beijing and four other cities in China may come across such a caution at "happy bus stations" in downtown areas.

Citizens in Beijing, Kunming, Xi'an, Zhengzhou and Shenzhen are being encouraged to share their feelings at test stations located in bus stations as well as the Sina Weibo, one of the country's top micro-blogging sites in a bizarre new commercial campaign.

At busy bus transit centers in those five cities, commuters are being asked to share their moods by choosing between two screens, one with a smiling face and one with a crying one. Participants can add to the running tally shown on the display every time they press the face that suits their mood.

The survey on the micro-blog site takes a further step, as participants are encouraged to explain why the city is making them happy or unhappy and why they are proud of the city they live in.

The campaign, launched by beer brand Carlsberg Chill, attracted 35,000 participants on the day it was launched, July 20. The online survey began on the same day.

The surveys conducted on the Sina micro blog and at the bus stations both revealed that happy residents outnumbered unhappy ones in every city, even though a larger percentage surveyed online said they were happy than those at bus stations.

The survey at bus stations showed that Xi'an was the happiest city, with 58.43 percent of commuters voting that way. Zhengzhou had 53.46 percent of voters saying they were happy, the least among the five cities.

Beijing scored highest in the online survey, with an overwhelming 76.6 percent of voters saying they were in a good mood. Zhengzhou again scored the lowest, with 63.9 percent saying they were happy.

"The rain last night cooled the hot weather," 72-year-old Beijing citizen Wang Zhong said to explain why he pressed on the happy face at a test station. "My wife and I both have good health and that's also enough to make me happy."

A netizen under the username "a children's music lover 2005", explained her unhappiness by saying on her micro blog: "There are too many traffic jams in Beijing. Every day it feels like I arrive home after a century."

Huang Xiaoru, a deputy researcher with the Institute of Policy and Management under the Chinese Academy of Sciences said: "Although the surveys use simple and random forms, they encourage citizens to interact with the city they live in and improve their sense of belonging and happiness."

The campaign is the second of its kind in 3 years. The 2009 campaign attracted 4.5 million participants in six cities across the country.