All synthetic school running tracks and sports fields in the Chinese capital are to be tested, state media has revealed, after toxic substances were discovered in at least one campus that apparently caused children to suffer nose bleeds, headaches, allergies as well as irritated eyes and skin.

Dozens of pupils at Beijing No.2 Experimental School’s Baiyunlu campus suffered a litany of ailments after running on the track last month. “Tests on the track this week, nine months after it was put into use, showed excessive amounts of benzene substances and formaldehyde,” reported China’s state newswire Xinhua, referring to highly toxic poisons.

Similar reports had previously emerged in China’s Jiangsu, Guangdong, Zhejiang, Jiangxi, Henan and Sichuan provinces. Authorities in Shenzhen tore up an athletics track last November after tests showed over 140 times permitted levels of the toxic chemical methylbenzene, according to the BBC citing the Beijing Bulletin.

Users of China’s Twitter-like microblog Weibo were quick to chime in with their own experiences. The hashtag #ToxicSchoolTrack has been trending in recent weeks.

“Exposed to the burning sun, unregulated plastic running tracks emit toxic gases, pouring into my child’s body,” posted one Weibo user. “Every day after school, my child goes to bed first because of a headache. For my child to grow up healthy, I would rather they use an unpaved, dirt playground.”

The discovery is the latest public-health scandal to grip Chinese parents, after the revelation in April that almost 500 children at a school near Shanghai developed serious illnesses traced back to the illegal dumping of toxic waste nearby. This is compounded by a general fear of excess air and water pollution and poor food safety.

“How ridiculous! We use students’ nose bleeds to test the quality of the running track,” posted another Weibo user. “Where is the regulation? Where are the inspection documents? Poor children become living detectors.”

In an apparent effort to curb public outrage, a commentary appeared in state media this week bemoaning the lack of a unified national standard on the quality of school running tracks, and urging “construction companies, regulators and school managers to be conscientious about their jobs and scrutinize work properly.”

Get The Brief. Sign up to receive the top stories you need to know right now. Please enter a valid email address. Sign Up Now Check the box if you do not wish to receive promotional offers via email from TIME. You can unsubscribe at any time. By signing up you are agreeing to our Terms of Use and Privacy Policy . This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. Thank you! For your security, we've sent a confirmation email to the address you entered. Click the link to confirm your subscription and begin receiving our newsletters. If you don't get the confirmation within 10 minutes, please check your spam folder.

Write to Charlie Campbell at charlie.campbell@time.com.