A four-day clampdown on private vehicles which removed one million from the China’s city’s streets saw pollutions tumble.
However, the smog over the city remained as humidity and low win prevented the haze from dispersing.
IOC president Jacques Rogge had expressed concerns over the pollution and the impact it would have on competition when Beijing hosts next year's Olympic Games.
Greenpeace campaign chief Chris Miller said: “Beijing may well be able to get levels to semi-acceptable for a short while to appease the Olympic organisers, but can they drop levels permanently?”
