SHANGHAI'S air quality watchdog, which began reporting the amount of PM2.5 particles in the air on Monday, had removed the data from its website by noon yesterday.
The figures had shown that the concentration of PM2.5 particles in the air in Putuo District and the Pudong New Area failed to meet China's new standard and at times were more than two and a half times higher.
The city's air had been described as "mediumly polluted" on the Shanghai Environment Monitoring Center's website, but just "lightly polluted" under the old PM10 standard.
Fu Qingyan, chief engineer at the center, said that the release of PM2.5 data was still under test and not stable so far.
She said the center had released real-time PM2.5 results from its two monitoring spots as a trial.
She didn't explain why the data had been removed from the website, but said 24-hour real-time data release imposed high requirements on data collecting, processing and equipment, and the center was perfecting the system in order to publish reliable data.
A Shanghai Environmental Protection Bureau official has said that Shanghai would officially release PM2.5 data from June.
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