XIAMEN, China, Jan. 2 -- IAAF President Lamine Diack has urged Chinese authorities to curb air pollution amid a boom of marathon races in the world's most populous country.

Speaking on the sidelines of the Xiamen International Marathon, Diack said good air quality is of vital importance for the health of distance runners.

"Xiamen is well known for its natural environment. It is Xiamen Marathon's unique resources to step to the top-level," Diack told Xinhua.

"Not all the cities share the same good environment as Xiamen. Bad weather is a big problem for Chinese cities managers to solve," he added.

Official data showed that 2013 has had the most smoggy days of any year in China over the last 52 years. Since the beginning of December, at least 25 regions and provinces across the counrty have reported high pollution levels, particularly of PM2.5, which are tiny floating particles measuring 2.5 micrometers or less in diameter. PM2.5 particles are especially hazardous as they can settle in the lungs and cause illnesses such as respiratory problems.

"Marathon is innocent," said Diack. "As an aerobic exercise, it has high demand for outdoor air condition.

"We believe China's government will make more efforts to control the pollution, focus on air surveillance and forecast the weather for local people. The haze should not curb the marathon race and the cities' managers should not slow down the pace to promote the sport."

Diack also expressed his surprise about Chinese cities' interest in hosting marathon races.

"It was in 1970s when I came to China for the first time. All these years passed, I'm a witness of China's development of sports, especially in city marathon," he said.

A total of 44 marathon were staged in China in 2012, up from 22 in 2011. And even more races are slated for 2014, according to the Chinese Athletics Association.

"The increase of races and participants shows that the sport has become more and more popular," Diack said.

Diack said that Chinese marathon organizers should keep pace with world top events which have relatively wealthy experience.

"Berlin has the plat course and London has intensive connection and cooperation with IAAF," he said, suggesting Xiamen to consult these committees for advice.

Diack also said that Chinese athletes and coaches should strengthen contacts with the top teams in track and field.

"Kenya, Ethiopia and Jamaica are all good teachers that we should learn from. IAAF would help to negotiate if necessary," he said.