Hong Kong Politics & Protest

Campus soil and water samples show negligible health hazards from tear gas, says Chinese University of Hong Kong

The Chinese University of Hong Kong (CUHK) has said that test results from soil and water samples taken from campus show negligible health hazards, after a large number of tear gas rounds were fired.

Last month, police and protesters engaged in dramatic clashes over the control of the university’s no.2 bridge. Police said protesters had been throwing objects onto the Tolo Highway from the bridge to block traffic.

According to police figures, 2,330 rounds of tear gas were fired across Hong Kong on November 12. A significant number were fired at the university during the clash. It sparked concerns as to whether soil, water and air at the university would be contaminated with the by-products of tear gas, such as cyanide and dioxins.

protesters clash police Chinese University of Hong Kong CUHK

Protesters take cover during clashes with police at the Chinese University of Hong Kong (CUHK), in Hong Kong on November 12, 2019. Photo: Citizen News.

Dioxins can cause cancer, reproduction and developmental problems, according to the World Health Organisations. They are highly toxic and can also interfere with hormones and the immune system.

CUHK appointed an independent accredited laboratory to collect air, water and soil samples at different times on campus for testing.

Some of the early results were released on Friday. The university said the results for the remaining soil, water and air samples will be released immediately upon receipt. They included two dozens of soil and air samples, as well as two water samples, taken near the no.2 bridge.

For the data already released, the university said that the dioxins levels for soil samples taken on November 19 were well below the standard published by the Hong Kong Environmental Protection Department: “It reveals that the hazards or risks to human health arising from exposure to soil are minimal, and measures to protect public health, including a cleanup, would not be necessary,” it said.

The level of dioxins for water samples were not significant when compared to the drinking water standards from United States Environmental Protection Agency, CUHK said.

CUHK test samples

Photo: CUHK.

CUHK said the values for total cyanide, carcinogenic chemicals total polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) for the samples were all well below safety limits.

“This implies that the health hazards from these contaminants in soil and water samples are negligible,” the university said.

CUHK test samples

Photo: CUHK.

The university’s head Rocky Tuan inhaled tear gas during the clashes without any protective gear and felt unwell as a result. He was admitted to hospital four days later, and was discharged around two weeks later.

MTR damage 

During the clashes, some people damaged the local station and a parked train in order to hinder the police deployment.

MTR Corporation Operations Director Adi Lau has said that the MTR system has suffered the most serious malicious damage in 40 years.

Lau told a Subcommittee on Matters Relating to Railways at the Legislative Council on Friday that University Station will almost have to be rebuilt following the damage. He said the transit firm was trying to partially reopen it by the end of December.


Hong Kong Free Press relies on direct reader support. Help safeguard independent journalism and press freedom as we invest more in freelancers, overtime, safety gear & insurance during this summer’s protests. 10 ways to support us.

fundraising fundraise banner

Campus soil and water samples show negligible health hazards from tear gas, says Chinese University of Hong Kong