On Wednesday, Beijing's office for severe air pollution emergency response issued an alert for hazardous air, the first warning after the Asia-Pacific Economic Cooperation (APEC) meeting in Beijing concluded just a few days ago. There is mockery online that now Beijing is bidding farewell to "APEC blue."

Even during the "APEC blue" period, there was already wide understanding that the smog-curbing measures were not sustainable and the social costs were just too high to bear. The air-clearing solutions adopted during the APEC forum have proven effective, but as Ma Jun, head of the Institute of Public & Environment Affairs, has pointed out, we can't just simply copy the "APEC blue" prescription.

The biggest legacy of "APEC blue" is that it demonstrates clearly what costs we need to pay in order to bring the blue skies back. As many experts have explained, judging from the pollution combating measures during the high-profile conference, in order to sustain "APEC blue" China must gradually restructure regional industries, especially the heaviest polluters.

Compared with traffic restrictions, measures aimed at cutting emissions by enterprises like coal-fired power plants bring a more noticeable effect. After the APEC meeting, not only should industrial restructuring be accelerated, but monitoring of enterprises' pollution emission must be strengthened as well. More of such numbers should be publicized, so that the public can participate in supervision. These numbers can also be used in pollutant tracking and studies of pollution sources.

The smog after "APEC blue" mirrors the plight of China at this stage of industrialization. The whole of society is wavering between the need for material profits and environmental interests. It is a severe challenge for both authorities and the public.

In the long process of pollution alleviation, it can be expected that whenever smog blankets Beijing there will be hash criticism. The smog is like a warning against China's way of modernization. But it should not stifle our hopes that Chinese will be able to gain both blue skies and social development.

It will still take time before the current stage of mass infrastructure building comes to an end. But as times goes by, pollution caused by construction is set to be limited by stricter standards. It should be a painful, yet hopeful way ahead.

The trajectory of the air pollution index after "APEC blue" has created a hot spot for debate over the smog issue. The government's stance is clear. It is attaching no less importance to environmental protection than to development. Blue skies are very costly, and sustaining "APEC blue" doesn't mean sacrificing development. China must find the way of affording blue skies while its momentum of development goes on.