The top environmental official in Shanghai recently said that it is illegal for the U.S. consulate in Shanghai to publish PM2.5 readings. China's Vice Environmental Minister Wu Xiaoqing said Monday that PM2.5 data from certain foreign embassies and consulates in the country may not be standardized or rigorous, and their publication of the data is not in line with international conventions or the country's laws and regulations.

Wu said that there are stringent technical requirements for monitoring air quality, involving the distribution of monitoring stations, monitors' qualifications, analysis of monitoring data, and selection of monitoring equipment. Furthermore, strict quality control measures must be adopted to ensure accurate air quality information.

"It is unscientific for certain foreign embassies and consulates to evaluate the air quality of an entire area based on data from a single monitoring station," Wu said, adding that the Ministry of Environmental Protection had previously warned them about that.

Wu noted that the United States has 1,000 PM2.5 monitoring sites, France has 700 such sites, and the United Kingdom has 400. New York City has 20 PM2.5 monitoring sites, Paris has 18, and London has 31. It is a common practice among these cities to release the average daily and annual air quality readings based on data from a network of monitoring stations.

In fact, the daily average PM2.5 readings published by environmental protection bureaus in Beijing and Shanghai are roughly similar to those by certain foreign embassies and consulates, but the assessments are distinctly different. Wu said that it was because they applied their own countries' air quality standards to China. The current air quality standards adopted in China are in line with the country's development level, and are indeed different from the standards in the United States and other developed countries.

At a high-level conference marking World Environment Day, China's Environmental Minister Zhou Shengxian said that the country's PM2.5 standards met the minimum recommended level by the World Health Organization.

China requires concentrations of PM2.5, particles less than 2.5 micrometers in diameter, to be kept below daily averages of 75 micrograms per cubic meter, while the U.S. standard is 35 micrograms. Wu said that the U.S. standard has been raised gradually. The United States required PM2.5 concentrations to be kept below 65 micrograms per cubic meter when it began releasing PM2.5 data in 1997. The standard was not raised to 35 micrograms until 10 years later.

Wu noted that environmental protection authorities will release more information on air quality in order to uphold the public's right to know. In the second half of the year, 74 major cities in the country will release more complete air quality data, including PM2.5 readings.