Parents of students at a Beijing primary school gathered at the school on Wednesday to demand a thorough test of its running track and classrooms after they found at least 30 students were suffering from regular nosebleeds.

An online video that was live-broadcasted by one of the 47 parents of students at Olympic Garden Experimental Primary School of Beijing Normal University showed them speaking with the school's headmaster about using stricter standards in tests of the school's facilities.

The parents suspect the school's running track contains toxic substances that may have caused 30 out of 40 students in one class to suffer from regular nosebleeds, while a physical examination found 177 of 200 students were unhealthy.

Toxic running tracks have become a hot topic recently after dozens of students at the school allegedly suffered from nosebleeds, dizzy spells and coughs after running on the synthetic track.

On June 3, Beijing's educational authorities started investigating school playgrounds built in the city in 2015 after parents voiced anger and concern that the primary school's track had sickened their kids.