The red alert requires a shutdown of schools, construction and other industries in the city. While the pollution has been even higher recently, officials expect a significant increase i the coming days. These levels mean that some people can fall ill simply by being outside on the streets.
The air pollution monitor operated by the US Embassy that the level of the poisonous, tiny particles of PM 2.5 as 291. The World Health Organization considers 25 micrograms per cubic metre to be a safe level.
On Tuesday, the levels were 15 times higher than the allowable levels under the World Health Organization. Millions of cars were ordered off the streets and the city left in a shroud of pollution.
Beijing is not even the most polluted city. Indeed, some of the countries now opposing restrictions on air pollution in the climate change conference top the list of the most lethally polluted cities. Here are the top ten:
1 Delhi, India 153
2 Patna, India 149
3 Gwalior, India 144
4 Raipur, India 134
5 Karachi, Pakistan 117
6 Peshawar, Pakistan 111
7 Rawalpindi, Pakistan 107
8 Khormabad, Iran 102
9 Ahmedabad, India 100
10 Lucknow, India 96