「“Toxin Fears Trigger School Running Track Furor”」 

By Trainee Reporter Zhou Chen, Caixin Weekly Zhao Han, Intern Reporters Zhou Hang and Jin Ying

Part I: Where did the “abnormal symptoms” come from?

On 22 June 2016, anxious parents at the Beijing Second Experimental Elementary School’s Baiyunlu Annex (hereafter referred to as Baiyunlu Elementary School) finally received an answer in the form of a lab report.

One serious question had been on parents’ minds for more than a month: was the school’s polyurethane (PU) running track toxic? After constant questioning and effort, testing from the Shenzhen-based company Emtek overturned the previous conclusion that the track met certification requirements. Using testing standards that surpassed national requirements, the report showed that the track had higher-than-acceptable levels of several contaminants.

In addition to the fact that the running track contained toxins that were not regulated by national standards, air samples collected in more than a dozen classrooms at the school showed excessive levels of formaldehyde. While not high enough levels to cause acute poisoning, excessive formaldehyde in the air could still be detrimental in the long term.

Toxic running tracks have been discovered in many places across China in recent years. In many of these cases, concerned parents connected their children’s symptoms of illness with strange-smelling running tracks. In their opinion, the nose bleeds, vomiting, rashes, and other symptoms were no doubt caused by these new PU tracks. As cases piled up from Jiangsu, Guangdong, Zhejiang to Beijing, anxious pleas from parents gradually drew increasing public attention to the foul-smelling running tracks.

It remains to be determined whether the students’ symptoms in these cases were indeed caused by the PU running tracks. In the cases reported on by Caixin journalists, the “toxic track” panic spread via social media, and most parents first heard about the news before noticing symptoms in their children. Tests from authoritative hospitals do not show any abnormalities among the children who suffered symptoms such as nose bleeds.

As food safety and pollution incidents continue to rise, Chinese parents are already suffering from hypertension due to a feeling of insecurity. However, if not for the “irrational” anxiety and hypersensitivity seen among the children and parents, when would we ever uncover the truth behind these “toxic tracks”?

Panic spreading among schools

According to Qi Lin (not her real name), the mother of a girl in fourth grade, she might have been the first parent at Baiyunlu Elementary School to have shown concern about the toxic running tracks. In her account to Caixin reporters, when she waited at the school gate each day at noon in 2016, she would always smell a “running track odour.”

A very caring and sensitive mum, Qi Lin doted heavily on her 10-year-old girl. Due to concerns about her daughter’s nutrition and health, Qi Lin never let her have lunch at school in her four years as a student there, and she was constantly mindful of the girl’s development.

“From November 2015 to June 2016, she only grew 5 cm,” Qi Lin told us. At first, she only felt anxious because her daughter was not growing as tall as she should. But a health check at school in February 2016 found that her daughter’s eyesight had worsened from normal to short-sightedness of 4.2 diopters. Qi Lin was stunned: her 10-year-old girl was now the first in the family to become short-sighted.

When she felt the smell of the school’s running track again, Qi Lin began to have suspicions. Since she had often read about “toxic tracks” on the internet, she started to panic: were there also issues with the running track at Baiyunlu Elementary School? 

Most of the parents waiting to pick up their children at the school gate were mothers. They would often talk among themselves about their children’s performance at school and in after-school classes, issues related to finding a good junior high school, and their health and nutrition.

“One day, another mum told me that in her child’s class, someone had six nose bleeds in ten days.” When Qi Lin relayed the news in the parents’ group chat on WeChat, a handful of other parents finally began to show concern and also started to follow news related to “toxic tracks”.

In May 2016, Baiyunlu Elementary School held a parents’ meeting to prepare for the school’s sports festival. Qi Lin immediately sent a message to the group chat, telling the parents to raise concerns about the foul-smelling running track at the meeting. At this point, most of the school children–like Qi Lin’s daughter–had been practising the mass gymnastic dance on the field for more than a month. 

Wang Shan (not his real name) only realised that there might be issues with the school’s running track after the parents’ meeting. Upon this realisation, he felt that there might be something suspicious with his son’s nose bleeds. In his account to Caixin journalists, he said that his son, who was attending third grade at Baiyunlu Elementary School, often suffered from nose bleeds before, but the situation had become ‘strange’ in the past few months: unlike before, his nose bleeds were now really hard to stop. 

Chatter surrounding the odour of the PU running track picked up in the parents’ group chat after the meeting. When comparing the situation with previous reports of “toxic tracks,” they found that many of their own children showed the same symptoms as in the reports, specifically nose bleeds and vomiting. 

Within the group chat, every single report of their children’s situation would raise concerns, as the mothers in the group became increasingly sensitive. The mums would talk about who got a nose bleed today, who developed a rash, or who threw up. According to Wang Shan, his son had an infection on his foot that they believed was athlete’s foot, but now they thought it was likely an allergic reaction to the toxic running track. 

More and more parents were talking about their children’s symptoms in the WeChat group by late May. Since the children had spent more than 20 days rehearsing on the track grounds at that point, the parents were now convinced that their children’s symptoms came “from the toxic track”.

As more and more parents took their children away from school, they began raising questions among officials and authorities. Their anger only grew after a dozen or so parents went to the city’s Education Commission and got no response. In the end, the angry parents gathered in front of the school gate to press the school authorities for an answer.

The news of the “toxic track” at Baiyunlu Elementary School quickly became one of the hottest news topics among parents in Beijing. The panic continued to spread: at the Shangdi Experimental Elementary School in Beijing’s northwestern Haiding District, a parents’ WeChat group quickly reached the maximum 500 members within an hour. Many shared accounts of their children developing symptoms including nose bleeds, dizziness, and rashes within the year, which “especially concentrated within the past one or two months”.  

Meanwhile in Beijing, the Zhanlan Road First Elementary School and Pinggu Sixth Elementary School also saw parents confronting the school about nose bleeds among the students, and the schools responded by digging up the top layer of the running track. The parents then quickly began to demand that the schools do the same as Baiyunlu Elementary School and “dig until only dirt is left”. 

Abnormal symptoms 

Children with bloodied noses and napkins in their hands, weak little arms filled with rashes: photo after photo on WeChat chilled each parent to the bone. 

According to the parents, nose bleeds were the symptom most commonly associated with the “toxic tracks.” Tang Ning, a parents’ representative at the Shangdi Experimental Elementary School, said that her daughter had five nose bleeds within a month, and through her interactions with other parents, she found out that nose bleeds were quite common among the students in her daughter’s class. 

The parents’ concerns were not reflected in the school’s data, however. One of the directors at Shangdi Experimental Elementary School, surnamed Liu, told the parents that the teachers had done their own survey of student nosebleeds, and found that there was no significant concentration of the issue. 

In Liu’s words, “The children often suffer from ailments near the final exams period, especially since this comes right when spring turns into summer. Bleeding can be the result of heightened activities, dry weather, or psychological pressure.” 

A teacher at the school also told Caixin reporters that her own daughter was in third grade at the same school, and the records in her class showed that in the course of three days, only two children had one nose bleed each, so there was no such thing as constant nose bleeds.

According to the parents at Shangdi Experimental Elementary School, the children’s symptoms also included dizziness, headaches, nausea, fever, and rashes.

At the Happy Baby Preschool in the Huilongguan community in Beijing’s Changping District, the symptoms caused by the “toxic track” there included ailments often seen among toddlers, such as not wanting to eat, diarrhoea, and night terrors.

However, some parents have described abnormal symptoms. 

As one parent told Caixin journalists, their child’s eyesight grew weaker and weaker during the six months when the school had the PU running track. Another said that their ten-year-old child inexplicably developed high blood pressure. A father said his daughter would become dizzy for no reason, and he said that she saw “a blue light” during a spell of dizziness. 

“Have you gone to the doctor’s yet?” asked the principal of Shangdi Experimental Elementary School during a meeting with parents on 21 June, when one of the parents described their child’s symptoms. 

“We have, but the doctors found nothing,” the parent angrily replied. 

Once students at Baiyunlu Elementary School began quitting class, Ding Dawei, education commission director at Beijing’s Xicheng District, advised that parents take their children to the Children’s Hospital and Fuxing Hospital for physical checkups, and the school also brought in medical experts for on-site advice. 

But the parents soon felt that the hospitals designated by the education commission were giving the same prepared response.  Wang Shan firmly believes this was the case. In his words, a parent asked the doctor about some figures in their child’s medical report that were beyond normal range. The doctor replied that this did not mean anything. “What does that mean? How could an abnormal test result mean nothing?” said a furious Wang Shan. 

When asked if he took his own child to the hospital, Wang Shan said that they did a blood test, but they never went to the doctor to see the report because the doctor left after they did the test.

On 12 June, Zhao Gang, deputy director of the health commission in Xicheng District–where Baiyunlu Elementary School is located–reported on the students’ test results. According to him, the district health commission received the medical exam results and of 216 students as of 10 June. In these recent medical reports, 79 were in the normal range, while 137 had figures outside of the normal range. Of these, 97 showed no clinical symptoms, 33 had abnormal coagulation and would require followup visits, and seven showed signs of fatty liver or other diseases. No cases of acute poisoning or other blood-related diseases were found. 

Not a single report of poisoning

On 8 June, a number of parents from Shangdi Experimental Elementary School took their children to the People’s Liberation Army 307 Hospital for blood tests. 

The 307 Hospital features the first professional lab for clinical toxin and drug testing in both the PLA hospital system and Beijing, per the hospital’s website. The lab is equipped with the most advanced toxin testing equipment and staffed by experienced toxicologists, and can conduct rapid testing for 937 common toxins, drugs, and their metabolites. 

During those few days, the pediatric department at the 307 Hospital issued a notice, stating that recent events had led to parents all over the country coming to the hospital for poisoning and biochemical tests, resulting in a substantial increase in their doctors’ workload, disorder, and delays to treatments. 

When enquired by Caixin journalists, the hospital’s information department said that the “toxic track” reports caused this rush. According to a pediatric nurse, during the two weeks since the end of May, more than 100 children came to the hospital each day for tests related to “toxic tracks.” 

However, not one of the children was diagnosed with poisoning.

One of the parents at Shangdi Experimental Elementary School, surnamed Hou, showed Caixin reporters eight test reports. According to the parent, many children had higher-than-normal white blood cell and lymphocyte counts and some had immune system and blood clotting issues. 

But after reading these eight test reports, attending physician Li Peiying at the 307 Hospital’s pediatric department said that these eight children were fine. 

As an example, in one of the reports that the parent said showed “abnormal” figures, an eight-year-old boy diagnosed with “upper respiratory tract infection” had mostly normal blood test figures. The “blood clotting issue” claimed by the parent referred to the “prothrombin time” of 36.5 seconds, for which 22.7 to 31.8 seconds would be considered normal. 

According to Li, “Some deviations from normal values are to be expected, since the normal values refer to adults.” 

However, more and more parents brought their children to the 307 Hospital. According to one particular parent, who came all the way from the far northern province of Heilongjiang, their sixth-grade daughter came back with normal test results at their local hospital, but they had to bring her to a more authoritative institution to be safe. 

Among the recent surge of children coming to the hospital for tests, not a single one was diagnosed with poisoning. According to Li Peiying, “The parents should trust the doctors, there is no need to panic.”

An ear, nose, and throat doctor at another top-level tertiary hospital in Beijing stressed to Caixin journalists that nose bleeds were common among young children and were usually caused by dryness in the nasal cavity, allergies, or infections. Irritating gases might induce sneezing and lead to more nose bleeds, but definitive proof that the nose bleeds were caused by the running tracks would be hard to obtain; only a controlled test could provide concrete proof, but this would be ethically problematic. 

Even so, these could not allay the parents’ concerns. “Even if all the test come back normal, they cannot prove there’s no toxins in their bodies,” a parent told Caixin reporters, noting that anything slightly out of the normal in the children would cause the parents to panic. 

Parents’ actions 

When conflict with the parents fully escalated on 3 June, the security guards at Baiyunlu Elementary School called the police. On that day, several dozen parents blocked the school gate with banners calling for the school to engage in dialogue and tear up the running track. 

“I arrived there at 3 p.m.,” said Wang Shan. According to him, at one point someone at the school threw water at the parents to chase them away. Some parents stayed at the school gate until 5 a.m., but they saw no-one except the police. 

Even though neither the principal nor education commission members came, the parents’ voices were heard. Authorities at the infrastructure division of the Xicheng District Education Commission later told Caixin reporters that the commission was assembling a team of experts to conduct “national-standard tests” on the running track. On 5 June, the National Centre for Quality Supervision and Test of Building Engineering Materials took samples of the running track for testing. 

A week later, on the afternoon of 12 June, authorities from the Xicheng District Government and Education Commission held a conference, in which they announced the test results: aside from higher-than-acceptable levels of formaldehyde in a music classroom, all samples collected from the PU track and air in the classrooms returned test results that fell within national standards. 

Yet the report failed to silence the parents’ calls for the running track to be demolished. More and more parents joined in the protest by taking their children away from school. In Wang Shan’s opinion, even though most parents did not join their demonstration at the school gate that day, they still found another way to protest the school’s inaction.

According to a fourth grader who still attended school, during this period, only six children out of their class of 36 came to school. Across the four classes in fourth grade, which normally had more than 100 students combined, only 17 continued to come to school, “so they simply put everyone in the same class”. 

With so many absent students, Baiyunlu Elementary School finally had no choice but to deal with the running track. On 17 June, the school declared that all classes would be cancelled until the running track was removed.

“They refused to acknowledge the impact on teaching activities,” said Wang Shan, noting that long before the school cancelled classes, most children had already cancelled going to school themselves. 

Baiyunlu Elementary School took rapid action on 17 June: in just one morning, the running track’s PU surface and asphalt layer was mostly been removed and only two heaps of rubble remained, each nearly two stories high, while workers doused water on them to keep the dust from flying.

According to a parent who worked in road construction, and who witnessed the operation, roughly 20 cm of track surface was dug up, leaving only an exposed layer of black and yellow dirt and gravel, or “cement-stabilised macadam” in technical jargon. Even so, some parents thought that they should dig a few more centimetres, fearing that toxins might have seeped into the soil. 

Pictures of the dug-up running track at Baiyunlu Elementary School were forwarded again and again in the parents’ WeChat group chats at Shangdi Experimental Elementary School, giving them much encouragement. 

In a meeting with the school’s principal on 21 June, officials at Shangdi Experimental Elementary School released test reports that stated the running track there met national standards. In response, Tang Ning pointed out that the track at Baiyunlu Elementary School also met national standards but insisted that even if this were the case, the track should be removed if it gave off a foul odour. 

This meeting took place on a Tuesday. Children continued to file out of the gate after the end of classes that day. The running track issue had not yet impacted attendance here. After school, the school’s principle told the parents’ representatives that school and education commission authorities were looking into ways to eliminate the odour, but the track could not simply be dug away before a solution was found. 

“They demolished the track at Baiyunlu Elementary School. Don’t you care about our children here?” said the furious parents. 

“We’re just nobodies that no-one pays attention to.” In Wang Shan’s opinion, the parents at Baiyunlu Elementary School did not enjoy any higher status. They also phoned into complaint lines at all levels of the municipal government, who would kick their complaints around to different authorities. After going around in circles, they finally ended up back at the district education commission. 

Even preschools saw protests calling for running tracks to be demolished. At Huilongguan, one of Beijing’s largest concentrated residential housing communities with some 300,000 residents, some parents raised concerns about the running track at the Happy Baby Preschool, a privately-run, government subsidised institution. After the running track was completed on 1 May this year, many parents found that their children began to fall ill.

According to Wang Ying (not her real name), the parents could still feel “a pungent smell” coming from the track in early June. Her daughter, Meng Meng, began feeling a constant fever and cough after the track was completed, and was diagnosed with pneumonia after being hospitalised for more than ten days. According to the parents, the most common symptom was coughing, followed by high fever, nose bleeds, and rashes. The parents demanded that the school remove the running track, while Wang Ying took the extra measure of taking her daughter out of school. 

The running track at Happy Baby Preschool has now been demolished, but Meng Meng’s chances of retuning there are slim. School authorities demanded that Wang Ying hand over a list of ‘disorderly parents’ as a condition for Meng Meng’s readmission, but she has refused to do so. 

Second test report

According to the first report on the running track at Baiyunlu Elementary School, announced on 12 June that all the test results met national standards, except for the air quality in a single music classroom. However, the parents were unsatisfied with the conclusion, and they demanded that the tests be rerun in accordance with the stricter local standards set in Shenzhen.

After leaders at the Xicheng District Education Commission and Baiyunlu Elementary School agreed, on 12 June, further tests were conducted by Emtek, a Shenzhen-based testing company commissioned by the parents. Emtek’s Guangming division ran tests on samples collected at Baiyunlu Elementary School, following the “Quality Control Standards on Synthetic Sporting Grounds” issued by Shenzhen Institute of Building Research Co., under commission from the Shenzhen City Government’s Education Department. 

The results of this second test were announced on 22 June 2016. According to the standards set by Shenzhen, the running track at Baiyunlu Elementary School had levels of polycyclic aromatic hydrocarbons and short chain chlorinated paraffins that exceeded the recommended maximum, while some sample also showed levels of 4,4′-Methylenebis(2-chloroaniline) (also known as MOCA) that exceeded the recommended maximum. 

In particular, the recommended maximum for polycyclic aromatic hydrocarbons was 50mg/kg, but  the four samples collected had levels that were six to nine times higher than the maximum. The recommended maximum for short chain chlorinated paraffins was 1500mg/kg, but all four samples had levels more than 20 times higher than this. This might have caused what the parents called “track odour”.  

Even more astonishing was the reversal of the original air quality results: in the 16 classrooms where air samples were collected, formaldehyde levels all exceeded national standards. 

Formaldehyde is a Category I carcinogen, and prolonged exposure to low levels of formaldehyde can cause headaches, nausea, limb weakness, sensory malfunction, and suppressed immune functions, as well as drowsiness, memory loss, neurological weakness, and depression.

Even before the parents had time to celebrate the removal of the running track, they were suddenly confronted with another shock: what should they do now that the classrooms were also toxic?

[Diagram]
PU running tracks: low price tag comes with hidden costs

Porous polyurethane running tracks have become the most common type of synthetic running track in elementary and secondary schools in China, due to their low cost, ease of installation, and low maintenance requirements. Yet the low cost comes with risks that are now becoming evident.

Porous tracks
Cost: Cheapest
Characteristics: Quick installation, easy maintenance, cost-effective, most common choice for running tracks at elementary and secondary schools

Base: Asphalt or concrete
Sub-base: Black granules + transparent resin
Surface: EPDM granules + pigmented resin (red or other colours)

Common contaminants in main materials
Black granules: Often made from discarded tyres; most have excessive levels of polycyclic aromatic hydrocarbons, some have excessive levels of benzopyrene
Resin: Usually polyurethane; substandard materials contain excessive levels of TDI or MDI EPDM granules: Made from substandard materials with excessive levels of polycyclic aromatic hydrocarbons

Hybrid tracks
Cost: Mid-range
Characteristics: Used at most purpose-built venues, easy installation, aimed at higher-end market, suitable for international competitions, can be used in cold or high rainfall environments Prefabricated tracks
Cost: Most expensive
Characteristics: High longevity, prefabricated and easy to install, often used at professional-level athletics fields

The “Bird’s Nest” stadium for the Beijing Olympics used a prefabricated track made by the Italian company Mondo S.p.A.

Part II: The “toxic track” industrial chain

What exactly was the cause behind this proliferation of “toxic tracks”? Is it because construction companies are acting in bad faith and using subpar materials, lack of quality control in the construction process, or lack of transparency in the tendering and supervision process? The short answer is, all of the above are possible.

However, the central issue behind all of this is the overly lax national standards governing PU running tracks, which allow for unregulated conduct at every stage of the construction process. As one expert puts it, running tracks can be toxic even if they meet national standards. 

Across the numerous schools with “toxic tracks” that Caixin reporters found, the parents’ demands were clear: whatever the cause may be, the tracks should be dug up first. However, what kind of running track can be satisfactory to everyone, particularly since children need exercise during while growing? 

Outdated national standards 

PU running tracks were first invented in the 1960 and rapidly spread across the world after their debut at the 1968 Olympic Games, becoming the standard for international track and field competitions. 

According to industry professionals, PU running tracks can be classified into porous, hybrid, and prefabricated systems. Porous tracks are the cheapest to build and are thus most commonly chosen by schools. The construction process involves laying a base, formed by a transparent layer of polyurethane paste and black rubber granules on top of an asphalt or concrete foundation, then spraying a coat of red or other coloured polyurethane pigment and EPDM granules on the surface. 

Numerous cases of foul-smelling “toxic tracks” have arisen at schools across the country in recent years, and the conclusion that these tracks “meet standards” or “pass qualification” has largely failed to convince those concerned. 

According to Yue Fenpeng, director of consumer product testing at the Chinese Academy of Inspection and Quarantine’s general testing centre, in the past year the centre received samples from 200 running tracks around the country, of which 80% passed current national standards. Even under current standards, the overall quality of PU running tracks nationwide could still be improved. 

However, China still does not have mandatory regulations governing the quality of PU running tracks. The current national standards are merely recommended guidelines, and quality testing currently does not cover a wide range of toxins. “This leaves a lot of leeway for unscrupulous companies,’ say industry professionals, so that ‘even tracks that meet national standards may be ‘toxic’.”

According to Prof. Chen Jianding of the East China University of Science and Technology Material Science and Engineering College, and director of synthetic track testing at the Chinese Athletic Association, the current national standards were first drafted in 2003, and officially submitted to the Standardisation Administration of China in 2005 after numerous revisions. At the same time, the National Rubber and Rubber Product Labelling Commission revised their standards on PU running tracks. After numerous consultations and revision, the Standardisation Administration of China announced two sets of standards in 2011: GB/T14833-2011, governing “synthetic running surfaces”, and GB/T22517.6-2011, “Requirements and testing methodology for sports venues, Part I: Athletic fields”. Both of these standards were recommended guidelines only, with no provisions for enforcement. 

These two standards set maximum allowances for the following toxins and harmful materials: benzene, toluene, xylene, toluene diisocyanate, lead, cadmium, chromium, and mercury.

According to Shi Jianhua, council member at the China Environmental Protection Association, these were extremely strict standards for the time: “These standards were set in line with indoor requirements, which exceeded the abilities of many companies in China at the time, but we still announced these standards. This was why it took so long for the standards to be defined.”

However, Chen Jianding points out that when the standards were announced, limits on volatile organic compounds had been removed, while limits on benzene-based solvents and toluene diisocyanate were also relaxed. This left room for companies with substandard construction practices to use large amounts of volatile organic compounds—or even toxic solvents—when building PU running tracks. 

As noted by the Xinhua News Agency, demand for PU running tracks has surged with the growing sports market in China after 2000, with many smaller companies entering the competition. Currently, only about a dozen polyurethane manufacturers in China have been officially certified by World Athletics and the Chinese Athletic Association, but thousands of companies have been manufacturing such products with only limited quality guarantees. 

Furthermore, since the government removed restrictions on sporting goods and equipment manufacturing in 2015, thus lowering the bar for entry even further, nearly every construction company can now manufacture PU running tracks. According to some experts, this is perhaps the reason behind the surge of defective new running tracks in the past year or so.

According to Shi Jianhua, the market prices for certified porous running tracks is around 150 CNY per square metre, while hybrid tracks cost roughly 200 CNY per square metre and prefabricated tracks cost no less than 380 CNY per square metre. The PU running track industry has grown to be quite sizable, as many schools have installed these tracks. However, the low bar of entry and lack of supervision has often led to unrealistically low bidding prices, with some contracts for porous tracks awarded at 70 or 80 CNY per square metre. With prices so low, these tracks are certainly substandard. 

After the explosion of “toxic track” reports last year, the Shenzhen City Government’s Education Department commissioned the Shenzhen Institute of Building Research to establish “Quality Control Standards on Synthetic Sporting Grounds”. After the public announcement and call for public opinions in March 2016, this set of standards is currently in the trial phase. According to Shi Jianhua, who took part in drawing up the Shenzhen standards, this new set of standards has vastly improved upon national standards by expanding the scope of testing. The standard also set limits on polycyclic aromatic hydrocarbons, short chain chlorinated paraffins, and total volatile organic compounds–and it required testing and supervision for transported materials, construction processes, and the final product.

Not long ago, Shanghai also passed a set of limits on harmful materials in PU surfaces in local schools. 

On 13 June 2016, the Beijing Education Commission announced plans to establish a set of construction and supervision standards for all PU tracks and sporting surfaces in elementary and secondary schools in the city, in consultation with other municipal authorities. Before the standards are set, all construction of tracks and sporting surfaces at schools in Beijing will be halted.

Where did the toxins come from?

Toxic materials may be introduced into the running tracks at a number of stages during the process from material manufacturing to construction. Shi Jianhua, council member at the China Environmental Protection Association, and one of the draftees of the GB/T14833-2011 standard governing “synthetic running surfaces,” believes that the “toxic tracks” are the result of cost-cutting  measures or construction shortcuts made by material manufacturers and construction companies, either substituting in subpar materials, or adding in materials that should not be in the mix.

The second test of the running track at Baiyunlu Elementary School, which followed the Shenzhen standard, showed varyingly excessive amounts of polycyclic aromatic hydrocarbons, short chain chlorinated paraffins, and MOCA, for which no limits were set by national standards.

According to the Shenzhen standard, the maximum limit for polycyclic aromatic hydrocarbons is 50mg/kg, yet the four samples collected at Baiyunlu Elementary School exceeded this by six to nine times, at 454mg/kg, 362mg/kg, 498mg/kg, and 338mg/kg respectively. The limit for short chain chlorinated paraffins is 1500mg/kg, yet the four samples exceeded this by more than 20 times, at 39952mg/kg, 39756mg/kg, 29540mg/kg, and 32960mg/kg respectively. 

Documentation pertaining to the Shenzhen standard notes that polycyclic aromatic hydrocarbons are carcinogens that usually consist of two to seven benzene rings, of which benzopyrene is one of the most toxic. MOCA, another carcinogen, is primarily used as a catalyst for polyurethane materials mixed and poured on-site. 

Chlorinated paraffins are used as plasticisers and fire retardants in polyurethane surfaces, helping to enhance their physical attributes. The normal practice is to use non-toxic medium and long chain chlorinated paraffins in polyurethane, but these might contain toxic short chain chlorinated paraffins, either in trace amounts as impurities, or purposely added as low-cost substitutes for non-toxic chemicals. Therefore, it is necessary to set a limit for short chain chlorinated paraffins.

On 21 June 2016, the 30 Minutes Economy programme on CCTV Finance uncovered an illegal factory in Hebei Province that produced “black granules” for PU tracks using old tyres and other black-coloured garbage. Vast amounts of old tyres, worn cables, and waste rubber from unknown sources would be haphazardly pulverised and glued to form these “black granules”, which came with no manufacturer’s name or address, no instructions on their usage, nor any certification of their quality.

Yin Haibo, the president of a PU running track construction firm in Shanghai, also pointed to these questionable “black granules” when interviewed by Caixin reporters. PU running track projects in Shanghai have recently begun to use higher-cost EPDM granules for the base, instead of these “black granules”. According to the standards set by the Shanghai authorities, most of these “black granules” have 18 different polycyclic aromatic hydrocarbons that exceed limits, and some have excessive amounts of benzopyrene.

“If the industry has regulations governing the reprocessing of old tyres, turning them into PU running tracks can actually be a good thing for the environment, and indeed this is commonly done in Europe and the US. However, the lack of rigorous standards and supervision in China has led to the appearance of illegal factories,” says Qu Ruijing, deputy director of the China Association of Circular Economy.

After numerous reports of “toxic tracks” appeared in 2025, Shi Jianhua and others discovered that even EPDM granules could be tainted. Some factories used subpar rubber process oils when manufacturing EPDM, which could result in 18 different polycyclic aromatic hydrocarbons that exceed limits as defined by the Shenzhen standard. In addition to the granules, low grade polyurethane materials may contain toxins such as toluene diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), toluene, xylene, and formaldehyde. 

After reading data on chemical materials, some parents point to TDI and DMI as the contaminants that caused illness among their children.

However, Shi Jianhua notes that even in these so-called “toxic tracks”, tests have found no traces of TDI and MDI, and thus these chemicals should not be the main cause. “When exposed to air, TDI will rapidly bind with water molecules to form non-toxic compounds, which are generally not absorbed by the human body, and MDI reacts even faster.”

Yue Fenpeng also agrees. According to him, excessive amounts of toluene and xylene were most commonly seen in tests, found in around 20% of all samples submitted. Benzene and lead levels also exceeded the maximum in some samples. However, none of the samples had excessive amounts of TDI or MDI.

According to Yin Haibo, crews often use organic solvents as thinners to facilitate construction: “Most benzene-based solvents can be easily detected using national standard tests, but ester-based solvents cannot. Since the national standard does not define a limit, it is impossible to tell what is added during construction. The same is true for solvent oils and cyclohexanone, which have no limits set in the national standard.” 

In addition, some companies use heavy metals as catalysts to induce solidification or toxic plasticisers such as phthalates to increase track springiness.

According to Wei Wenfeng, who heads the non-profit testing organisation ‘Daddy Review’, a qualitative analysis of the running track at Yuhai Central Elementary School in Rui’an City, Wenzhou, Zhejiang Province found large amounts of carbon disulfide and 2-Methylfuran, both toxic compounds. According to Ren Jun, head engineer at the Shenzhen Institute of Building Research who helped draft the Shenzhen standard, carbon disulfide could either be present in subpar ‘black granules’, or used as an additive in solvents.

The new standards in Shanghai now define an upper limit for total volatile organic compounds, aiming to prevent the haphazard use of solvents during construction. The revised Shenzhen standard, currently undergoing public appraisal, also explicitly prohibit the use of gasoline and solvents—including benzene, toluene, xylene, carbon disulfide, and dichloromethane—during the construction of synthetic surfaces. 

What happens after the tracks are torn out?

During the discussions at Shangdi Experimental Elementary School on whether the track should be dug up, school authorities asked the parents a question: Once the “toxic tracks” are torn out, what should the school put in its place?

“Better to let our children hurt themselves on concrete, than to have them breathe in toxic fumes!” said one frenzied parent.

In the words of Guo Long, the lead draftee for new national standards on PU running tracks, asphalt is not a suitable surface material for running tracks in elementary and secondary schools, since they have largely the same environmental concerns, while tracks made of cinder or dirt will be plagued by dust. Concrete tracks seem to be the only choice, if one overlooks the hardness of the surface and long-term impacts on the children’s ankles.

Are there really no PU running tracks that meet qualifications? According to the Chongqing-based company that laid the track at the Beijing National Stadium, the running track at the “Bird’s Nest” stadium is a prefabricated model from an Italian brand, which passed rigorous testing for the 2008 Summer Olympics.

In contrast with the porous tracks in schools, prefabricated tracks do not require black granules that are mixed on-site. Instead, the materials are mixed according to a defined ratio in the factory, transported in entirety to the stadium, and then simply rolled out like a carpet by workers.

However, the track at the “Bird’s Nest” stadium cost nearly 1000 CNY per square meter, putting this solution out of the reach of most schools.

Shi Jianhua points out that schools in Europe and the US rarely use PU tracks due to cost restrictions, and such tracks are normally only installed in professional stadiums. In addition, World Athletics only defines the physical attributes of running tracks, and does not have requirements concerning pollutants and contaminants.

Some parents have suggested replacing the artificial track with natural grass, but as a PE teacher at Shangdi Experimental Elementary School explains, grass pitches are costly to maintain and cannot last into the winter. In her opinion, the shock absorption ability of PU tracks can help protect children from injuries during sports and exercises.

On 22 June, an official notice on the website of the Ministry of Education called for track construction projects tailored to the specific financial, geographic, and climate conditions of each locale, rather than viewing PU tracks as the one and only choice.

The notice further stated that relevant national authorities will coordinate to establish a suitable standard, and requested that supervisory authorities step up their efforts in monitoring the production of PU tracks, with a clearly defined division of labour to prevent flaws in the supervision process.

Finally, the Ministry of Education demanded that local education authorities and schools strictly adhere to requirements: quality requirements must be emphasised in sporting facility construction contracts, and quality must be the top priority during the bidding process, instead of simply looking at cost. Those responsible for “toxic tracks” will be held fully accountable.