Source: New York Times

Beijing plans to publish hourly air quality reports based on an international standard known as PM 2.5, which measures tiny particles that are 2.5 micron or less in diameter. Strides taken by Beijing, a top polluter in the world, could serve as a good example to Mongolia, where its capital currently is reported to be the most polluted city in the world during winter by the World Health Organization (WHO).

Big cities in China, including Beijing, generally publish air quality data that measure particles that are up to 10 microns in diameter. Using that standard has allowed Beijing to record more than 250 “blue sky days during each of the past two years. China's Ministry of Environmental Protection also said that monitoring pollution levels using the MP 2.5 standard would be included in a newly amended draft of national air quality standards.

Beijing's “blue sky days” have often turned up in the United States Embassy readings as “unhealthy.” In 2009 a Chinese Foreign Ministry official pressed the United States Embassy to stop reporting the data, saying the information was “confusing” and “insulting.” The embassy continues to release the readings via Twitter, although that website is censored by the Chinese government.

During the past year, smog has forced the city to periodically close highways, cancel flights and even cope with state-run media assaults on health problems caused by poor air quality.