China is not interested in publishing or monitoring air quality information in U.S. cities, said Foreign Ministry Spokesperson Liu Weimin in a regular press conference, when asked to reply the U.S. State Department's saying about welcoming China to monitor U.S. air pollution.

Earlier, China told foreign embassies on Tuesday to stop publishing their own readings of air quality taken in Chinese cities, saying that only the government could release pollution data.

Only the Chinese government has the power to monitor and publish air quality information and data from other sources is "not in accordance with the Vienna Convention on Diplomatic Relations," Wu Xiaoqing, a vice environment minister, told reporters at a news conference.

Wu did not name the U.S. specifically, but China has long taken issue with the U.S. Embassy's postings of hourly readings of Beijing's air quality on a Twitter feed, which has gained more than 19,000 followers since 2008. Last month, the U.S. consulate in Shanghai started a similar feed of its own.

The U.S. State Department said the embassy won’t stop issuing air quality data in Beijing because it is only offering information to U.S. citizens who live in China rather than interfering in China's internal affairs, according to Hong Kong-based Phoenix Television.

“The U.S. will welcome if China also wants to publish air quality information in U.S. cities,” State Department spokesman Mark Toner was quoted as saying.

Chinese internet users responded positively to the State Department’s reaction, using it to chide Chinese officials for the “childish” behavior.

Sina Weibo user @多阿多 said: “China is like a child, making trouble out of nothing with adults. The U.S. is educating a child, bringing out the facts and reasons.”

@沪港小生 said: “This [the U.S.’s answer] can be considered into textbooks on international relations.”

China's air quality is among the worst in the world, international organizations say, citing massive coal consumption and car-choked city streets in the world's biggest auto market, according to Agence France-Presse:

According to the latest Environmental Performance Index compiled by Yale University, China ranked 128th out of 132 countries for air quality.

Most Chinese cities base their air-quality information on particles of 10 micrometres or larger, known as PM10, and do not take into account the smaller particulates that experts say are most harmful to human health.

The Associated Press said the readings are based on a single monitoring station within embassy grounds, and pollution levels are rated according to a U.S. Environmental Protection Agency standard that is more stringent than the one used by the Chinese government.

For instance, the U.S. Embassy on Tuesday reported 47 micrograms of fine particulate matter in the air and said the level was "unhealthy for sensitive groups." Readings from Beijing Environmental Protection Bureau's 27 monitoring stations ranged between 51 to 79 micrograms, with all those levels categorized as "good."

China began considering updating domestics standards after drawing long-standing public and international criticism.

Earlier this year, the Beijing government began reporting PM2.5 -- particulate matter less than 2.5 micrometers in size, or about 1/30th the width of an average human hair.

PM2.5 are believed to be a health risk because they can lodge deeply in the lungs, and have been linked to increased cardiovascular and respiratory diseases and lung cancer.

A Beijing environmental official, Yu Jianhua, said on Tuesday that the environment authorities in Beijing will no longer count "blue sky days" as a gauge of air quality for the measure hardly reflects the specific situation in different areas of the city, the official China Daily reported.