Beijing chokes on highest smog alert

Beijing's 25 million citizens were on lockdown on Tuesday, as the Chinese capital suffered through its first ever pollution 'red alert'.

That alert level is the highest possible under China's Ministry of Environmental Protection air quality measurement scheme.

It is defined as 'severely polluted', and suggests healthy people will experience reduced endurance in activities, with everyone being advised to avoid outdoor activities and elders and the sick being told to remain indoors.

Beijing's municipal government reacted swiftly to the pollution event, ordering some factories to halt operations, and limits placed on car use. Odd numbered registration plates were ordered off the road on Tuesday, with even plates told to stay home on Wednesday.

The alert came into effect at 07:00 local time on Tuesday (23:00 GMT Monday). At that point, the air pollution monitor at the US embassy in the city was measuring 291 micrograms of harmful PM 2.5 particles per cubic metre.

As at 21:45 local time, it was at 328 micrograms per cubic metre.

By comparison, measurement stations in the City of London were reading 30 micrograms per cubic metre at midday on Tuesday. The World Health Organisation recommends a maximum safe level of 25 micrograms per cubic metre.

"Schools will be advised to close, while companies may adopt a flexible schedule under a red alert, which also bans activity at construction sites, transport of materials and waste, as well as firecrackers and outdoor barbecues", a Beijing government spokesperson said.

"Industrial plants blacklisted under the red alert would be shut down."

The red alert was expected to last until midday on Thursday local time (04:00 GMT).