APEC blue is gone. Smog is back.

Blue skies did not last long over Beijing after the Asia-Pacific Economic Cooperation conference from Nov 5 to 11. The capital and its neighboring provinces are once again shrouded in severe smog, primarily because of central heating in North China that requires burning huge amounts of coal.

APEC blue, a term coined by some Chinese netizens to describe Beijing's clear skies during the APEC week, was the result of both compulsory measures and favorable meteorological conditions. During the weeklong conference, emission-heavy production in Beijing and its neighboring provinces and cities - including Tianjin municipality, Hebei, Henan and Shandong provinces - was suspended and half the cars were forced off the roads because of the odd-even license number driving rules. Plus, the weather condition in Beijing at the time was relatively conducive to dispersing air pollutants.

APEC blue has shown that temporary measures do work in reducing air pollution, as Beijing's daily PM2.5 density during the conference fell to 43 micrograms per cubic meter. Yet such temporary measures are no substitute for long-term action to reduce air pollution.

The capital and its neighborhood should not be shrouded in "routine" smog. But to prolong the blue-skies and clean-air days in Beijing, all sides have to make concerted efforts to cut emissions and reduce air pollution.

First, the government has to be more determined to resolve smog-related problems in the long term. From the 2008 Olympic Games to the just concluded APEC conference, the Beijing municipal government has always ensured blue skies and clean air for all major events held in Beijing. But short-term efforts such as compulsory emission reduction are only a palliative, not the medicine for cure.