BEIJING IS VEILED IN THE WORST SMOG IN about six months, and the heavily polluted haze is expected to continue shrouding the capital and its surrounding areas in Hebei province and Tianjin. The air pollution control authorities updated its yellow warning to orange by the evening and advised people to take protective measures.

The city mayor's vow at this moment to make greater efforts for cleaner air in the capital, though made at a meeting for the preparations of the 2014 Asia-Pacific Economic Cooperation Economic Leaders' Week, can also be considered as a response to this health hazard.

It is not the first time the capital's leader has made such a pledge. And it is indeed not easy for a city with a population of nearly 30 million and more than 5 million cars to keep its air clean.