Smog and pollution levels in Beijing have reached unbelievable levels. When PM2.5 (suspended particulate matter smaller than 2.5 micrometer) level in the atmosphere reaches 300, it is considered hazardous for human health. In Beijing, the PM2.5 level reached 900 at the height of the recent "smog attack". In Shanghai, where I live with my family, things are better than Beijing, but still not good. Cities across China experience similar problems. We need to curb pollution now.

For the last couple of years, the focus has been on long-term solution, new research and smarter designs to reduce environmental pollution. These efforts should not only continue, but also be intensified. But they would still not be enough. In China, we need effective solutions and we also need a change of mentality.

The Danish government introduced mandatory car-free Sundays from Nov 25, 1973, to Feb 10, 1974, because of the 1973 oil crisis when oil prices shot up threefold because of the conflict in the Middle East. Danes where prohibited from using their cars for 11 consecutive Sundays. The only exceptions were the day before Christmas Eve and the special permits given to people like doctors, midwives and priests.

The main objective of the Danish government's policy was to conserve oil and it was a success. But the car-free Sundays served a much greater purpose. To this day, my parents talk about those Sundays without cars. They remember that the cities were a lot quieter with children playing in empty streets as if they had suddenly come to own them. They also remember people enjoying a day without stress and the national awareness and discussions about what it meant to be heavily dependent on foreign oil. This change in national mentality directly facilitated the development of wind power in Denmark.

So why can't we introduce car-free Sundays in Beijing, Shanghai and other big cities in China? Car-free days alone may not be enough to solve the environmental pollution problem in China, but they sure would be a good way to start the process.

Rasmus Duong-Grunnet, via e-mail

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(China Daily 01/22/2013 page9)