From 1975 to 2005, the average height of boys aged six years in China increased from 112.3 centimeters to 118.7 cm and that of girls, from 111.5 cm to 117.7 cm. This shows that, over the past 30 years, Chinese children's average height has increased by 6 cm.

The Beijing local government's move is especially welcome because the last revision on subway fares for children was done in 2005 and the latest move reflects the development of the times.

Local governments in other parts of China also should reconsider allowing children less of 1.3 m tall to travel free on the subway. After all, the benchmark was set years ago.

In 2010, the Ministry of Railways, which was dissolved three years later, announced that children up to 1.2m tall - against the existing 1.10m - could travel free on trains. A year later, the Shanghai local government raised the height from 1.2 m to 1.3 m. Now it is time for the country to comprehensively revise the national standard to suit social realities.