Beijing sees the return of severe air pollution on Thursday, showing the futility of efforts pledged when the Chinese capital grabbed global headlines a year ago with lung-busting smog enshrouding it.
Concentration of PM2.5, the fine particles most harmful to health, at one point on Wednesday night exceeded the 500 mark on the Air Quality Index measured by the US embassy.
By 10am on Thursday, it was hovering in the high 400s, similar levels seen last year.
The US embassy's recommendations for pollution at these levels are to wear masks, avoid outdoor activities and to provide protection to low-resistance groups such as the elderly and children.
The World Health Organisation guidelines regard anything above 25 as unsafe.
Visibility is reportedly limited to within 500 metres in Beijing and surrounding regions like Hebei province which is also suffering from serious air pollution.
Poor visibility was a likely key cause of a major chain accident on a Beijing-Kaifeng highway on Wednesday morning involving at least 30 vehicles and causing jams lasting over three hours, which this Straits Times reporter was caught in.
The smoggy saga in Beijing last year, which forced hundreds of flights to be cancelled or delayed amid visibility of within 100 metres and earned it the ignominious "Grey-jing" nickname, alarmed many Chinese which took to the cyberspace to vent their frustration.
Concerned of the dent to China's global image, the Chinese government has pledged tough measures against polluters and taken steps in that direction over the past year.
A latest report by medical journal Lancet and authored by four leading Chinese scientists showed air pollution to be responsible for 350,000 to 500,000 premature deaths each year, with high levels of PM2.5 particles posing the fourth biggest risk factor to public health.