The other 145 cities failed to meet the new standard, which was implemented in 2013 and includes a PM2.5 index for monitoring airborne particles measuring less than 2.5 micrometers in diameter. The tiny PM 2.5 can go deep into the lungs, posing a greater health threat than PM 10.

Some see vehicle emissions as a key contributor to poor air quality in megacities.

In many cities, including Beijing, road space policies are already in place to limit the number of cars traveling on the road.

Beijing even pulled half of the city's cars off the road during the Asia-Pacific Economic Cooperation (APEC) meetings last year, allowing even-numbered license plate owners to drive on some days and odd-number drivers to drive on others.

While some support the traffic bans in favor of better air quality, others complain that the restrictions equate to encroachment on their rights.

A number of lawmakers have thus called for stricter procedural requirements for imposing driving restrictions, said Sun Baoshu with the NPC Law Committee.

By soliciting public opinions, the draft amendment is expected to help find a balance.

Sun said the lawmakers will further research on the subject in future deliberations.