Chinese authorities are investigating playing fields at some of Beijing's top elementary schools after children reportedly fell sick from exposure to artificial turf.

Youngsters have suffered nose bleeds and allergic reactions after using running tracks, in the latest health scare to rock a country where safety standards are a major concern.

The news comes less than two months after reports that hundreds of students had been sickened elsewhere in China because of their school's proximity to shuttered chemical plants.

The Beijing probe, which began last week, sparked a wave of anxiety online, with hundreds questioning the country's commitment to protecting one of its most valuable assets: its youth.

The reports are a "nightmare", said one comment on China's popular social media platform Weibo.

"Where is the Chinese dream for those children?" it asked.

Toxic air and poisoned food already create dilemmas for Chinese concerned about their children's health.

Frequent reports of early onset cancer and respiratory ailments create a climate of fear for parents, many of whom who have only one child thanks to China's once strict birthing policies.

But the Beijing cases are particularly unsettling because they have occurred at schools attended by children of the capital's well-to-do.

"If Beijing is like this, it's even harder to imagine those campus fields in other cities," one commenter wrote.

In April, news outlets reported that almost 500 students were sickened after a top middle school relocated to a site close to decommissioned chemicals factories.

An undisclosed number of young people were diagnosed with leukaemia and lymphoma, both diseases often linked to pollution exposure.

In Beijing, authorities have vowed to deal with the issue and plan to release a report on the materials used to build the track next week.

In the meantime, a team of six doctors has been dispatched to check into any health effects, a statement from a Beijing education office said.

But the reassurances left commenters unmoved.

"It's no use to punish severely the school or the construction team," one commenter said.

The real question that needs to be asked is "how could this kind of product receive approval? What were the safety inspectors doing?"