Shanghai's hourly updated PM2.5 readings and a chart showing PM2.5 changes in 24 hours are available on the bureau's site, www.semc.gov.cn, and on its microblog. They are in Chinese, but the bureau said a bilingual version will be provided later.

Since March, Shanghai has released real-time PM2.5 figures at two monitoring spots in Putuo and Pudong's Zhangjiang area.

Shanghai has established 30 PM2.5 monitoring spots, including 10 national spots which are mostly in downtown districts. A spot in suburban Dianshan Lake is used as a benchmark for good air quality and is not included in local air quality evaluations.

However, the PM2.5 readings at Dianshan Lake in Qingpu District was the highest among all the 10 spots yesterday since the ocean breeze from the east carried an accumulation of particles into the city's western Qingpu area.

Officials said they may reconsider placement of the benchmark spot since Dianshan Lake is likely to be influenced by pollution from nearby districts.