Air quality: now you see it, now you don't

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. According to the environment monitoring center's website, the amount of PM2.5 particles in the air was 150 to 200 micrograms per cubic meter yesterday morning. On Monday night, the Pudong figure was 118 and that had risen to 201 by yesterday. The new Chinese standard, passed by the State Council last Wednesday, requires concentrations of PM2.5 to be kept below a daily average of 75 micrograms per cubic meter. That compares to the United States Environmental Protection Agency's standard of 35. Yesterday's pollution was mainly because of a haze enveloping the Yangtze River Delta Region, the monitoring center said. The weather bureau said the main reason was dirt brought in as the result of a cold front and the wind. The PM2.5 measure monitors "fine" particles measuring 2.5 microns or less in diameter. Experts say these are small enough to lodge in the lungs and even enter the bloodstream. Shanghai was one of the first cities chosen to carry out PM2.5 and ozone monitoring in a program to be introduced across China before 2016.