Another batch of students in China experienced nosebleeds, whooping coughs, sore throats, dizziness or inflammation in the eyes following activity on a newly laid running track, reinforcing belief that many such surfaces constructed in the country's schools contain "toxic" materials.
An education official from the district in north-eastern China's Dalian city, where the primary school is located, told The Paper news portal on Monday that a check on the air in the school's classrooms found it was all right.
But an inspection on the running track, on which hundreds of students had gathered last Wednesday for a charity fair, is still ongoing, he revealed.
The track is closed pending the investigation.
The official claimed that he did not know how many students were affected, but the Shanghai-based portal counted at least 64 complaints posted online by parents.
"The weather last Wednesday was very hot and there was an unpleasant smell on the running track," a parent told The Paper.
A company based in eastern China's Jiangsu province, which laid the running track in the Dalian school, said when it handed it over to the school in January, the track passed all quality tests stipulated in the checklist.
According to Shi Jianhua, a chemistry expert, the students' indispositions must be due to the presence of the chemicals toluene and xylene in the building materials.
"In some cases, paint thinner and gasoline are added, and because the surfaces are about 1cm thick, the foul smell will take some time to go away," added Mr Shi, who had helped in drafting the national guidelines for the construction of rubberised tracks used by professional athletes.
According to the official Xinhua news agency, since last year, untold numbers of students in at least 12 provinces - as well as Shanghai and Beijing - had complained of physical distress likely to have been caused by "toxic" runways.
It is an urgent task now to perfect the rules on what materials to use in the construction of running tracks in schools, how they are laid, and the type of gases they are not allowed to emit, said Xinhua.
"China does not lack the expertise and knowledge. What we lack is stringent supervision," it added.
A netizen wrote: "We keep hearing news about toxic running tracks and yet the problem is not eradicated."
"Often, each case would end with the closure of a running track, but all probes seem to produce no conclusion. If we don't tackle the problem seriously, we will one day see our innocent children being buried," the netizen warned.
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