Residents in the Chinese capital were today asked to remain indoors as the city was choked by heavy smog, prompting Beijing air control authorities to issue an alert for hazardous air.
The smog cover over Beijing was a stark contrast to "APEC Blue" or clean skies that greeted world leaders during the Asia-Pacific Economic Cooperation summit last week.
The clear skies during the summit was a result of smog-control efforts by authorities.
Beijing's office for severe air pollution emergency response issued a blue alert, blaming regional pollution and unfavourable weather conditions for the build-up of pollutants, state-run Xinhua news agency reported.
A blue alert is the lowest of a four-level warning system.
Beijing's air quality index hit 348 with the index of PM2.5, the smaller but more harmful particles, standing at 348, which are considered to be harmful.
The office has ordered local pollution emitters to take stricter measures to cut emissions, and advised residents to stay indoors and to wear masks when venturing out.
Children, the elderly and those who suffer respiratory and cardio-cerebrovascular diseases are urged to reduce outdoor activity.
At least 11.7 million vehicles were taken off roads and 10,000 factories were shut down by China to ensure a pollution-free APEC summit.
The government had also squeezed 4.34 lakh officials for "APEC Blue" or clean skies for the summit attended by top world leaders including US President Barack Obama.
