HONG KONG—On a Sunday in November, Chau was out with her family to have a meal in her neighborhood, a residential area known as Tsuen Wan. While sitting outside the restaurant, she heard a loud bang.
Chau saw that tear gas had enveloped the street. She began to cough and tear up. Her daughter, almost 3 years old, was also caught in the cloud of tear gas.
Tear gas has become a common presence since protests ignited in June, in opposition to an extradition bill that would have allowed the Chinese regime to transfer individuals for trial in Communist Party-controlled courts.
While the bill has since been withdrawn, Hongkongers continue to protest, asking the government to address other demands, including for an independent inquiry into police use of force against demonstrators and for genuine universal suffrage in city elections.
Since June, police have fired roughly 10,000 tear gas canisters and grenades across all districts, except for a group of outlying islands to the southwest of the city core.
While on that afternoon in mid-November, protesters had gathered in Tsuen Wan as part of citywide demonstrations, by the time Chau and her family had begun eating, the protesters had already gone, she said. Most people who were still on the streets were locals who weren’t wearing gas masks or other protest gear.
Not long after, her daughter developed a persistent cough and a lot of phlegm.
The doctor prescribed some cold medicine, but was unsure how to relieve the phlegm condition. Weeks later, her daughter’s condition improved, but hadn’t gone away.
“The government should disclose the tear gas components so doctors know how to treat,” Chau said.
Hong Kong authorities so far have refused to disclose the chemical makeup of the tear gas that police use during demonstrations.
The most common chemical compounds used in crowd-control agents are chlorobenzylidene malononitrile (CS) and ortho-chloroacetonphenone (CN).
On Nov. 20, the city’s health secretary Sophia Chan told lawmakers that the chemical components and manufacturer details for the tear gas used by police couldn’t be revealed, as the police force said it could affect their operations.
But residents, dissatisfied with the government’s response, are growing increasingly concerned that the police’s continued dispersal of tear gas could have long-term negative health and environmental effects. In recent weeks, protesters have posted images online of their skin rashes after being exposed to tear gas during demonstrations.
On Nov. 27, a group of parents called “Hong Kong mothers against the extradition bill” released the results of a survey they conducted with 1,188 parents of children under the age of 18.
Among the respondents, 16.5 percent said their children’s health suffered from contact with tear gas on more than one occasion. Most of those children lived in areas heavily hit by tear gas in recent months, such as Yau Ma Tei, Tsim Sha Tsui, and Mongkok.
Of those who said their children were negatively affected, 65.1 percent said they had coughing, 55.5 percent said dry throat, and 50.9 percent said skin irritation (parents could note multiple options). Adverse reactions persisted for an average of six days.
Alastair Hay, a British toxicologist and environmental toxicology professor at the University of Leeds, said that most symptoms of CS gas exposure, such as difficulty breathing, coughing, and tearing up, are short-term. But people with respiratory conditions, such as asthma, would be more susceptible to prolonged health effects due to exposure to tear gas.
Children are also more vulnerable, as they “have a higher respiratory rate than adults, so will inhale more [tear gas],” Hay said, and they have immature immune systems.
Using tear gas in confined spaces—as Hong Kong police have been documented to do—also increases the likelihood of prolonged symptoms. International guidelines on tear gas dispersal stipulate that it be fired in open spaces, otherwise, there is risk of high exposure and also of people being trampled when trying to escape the gas, Hay said.
And while there has been no documented case of illness as a result of exposure to the toxic chemical dioxin released from tear gas, Hay said that scientific research on the long-term effects of tear gas exposure is lacking.
As for the environmental impact, Hay said it’s likely that CS would “contribute marginally” to air pollution. However, due to the dispersal of tear gas in confined spaces, people downwind, who aren’t involved in protests, could be exposed to the chemicals and “may well experience symptoms.”
Police often leave spent canisters on the ground, while warning residents not to pick them up. Hay said leaving canisters on the ground means residual CS in the canisters could be active for days or even weeks.
Meanwhile, experts are increasingly concerned about the possibility that tear gas rounds could be heated to dangerous levels, thus producing toxic by-products when police fire them.
In mid-November, a journalist from local online news outlet Stand News, who frequently reports from the front line of the protests, was diagnosed with chloracne, a skin condition linked directly to dioxin exposure, according to medical research.
Dioxins are toxic chemical compounds that are known to be environmental pollutants and can cause liver damage, as well as disruptions to the immune and reproductive systems in the long-term.
At a press conference, the police force subsequently admitted that tear gas has the possibility to release dioxin.
The diagnosis drew alarm from experts.
The Public Health Research Collaborative, a group of public health scientists in Hong Kong, issued a statement explaining that dioxin can be produced when CS or CN is heated to 250 to 450 degrees Celsius (482 to 842 degrees Fahrenheit), along with the presence of a metal—such as copper, aluminum, or iron—acting as a catalyst for the chemical reaction.
On Nov. 22, a group of former and current members of an environmental advisory council to the Hong Kong government co-signed an open letter to city leader Carrie Lam: “It has been shown that high-temperature dispersion of CS tear gas could liberate hydrogen cyanide, hydrogen chloride … and several other toxic chemicals,” the letter read.
Hydrogen cyanide is an asphyxiant and can cause loss of consciousness, while hydrogen chloride is an irritant that can burn the eyes and respiratory tract, according to Hay.
The co-signees urged the city to conduct a study on the environmental and health effects of exposure to tear gas and other crowd-control agents. They also asked authorities to issue clear instructions to police on proper use, and to residents and city clean-up staff on how to cleanse tear gas residue.
K Kwong, a Hong Kong-based chemist, is concerned that toxic by-products such as dioxin could accumulate in people’s bodies. Because dioxin doesn’t dissolve in water, it absorbs into the skin, and can be “stored in your lipid cells in your body for an entire lifetime,” he said in an interview with The Epoch Times’ sister media NTD.
Regardless of one’s political views on the protest movement, Kwong said, it’s imperative that the government disclose the chemical makeup of the tear gas they use, as well as conduct regular environmental readings.
“If it makes Hong Kong too dirty or dangerous to people, no matter [if] you are pro-government or anti-government, everyone living in Hong Kong or tourists visiting Hong Kong will get hurt,” he said.
Short of a government investigation, some journalists from local online media HKGETV have taken it upon themselves to analyze the tear gas emissions and residue.
In one report, HKGETV used a handheld gas detector to determine the levels of hydrogen cyanide at the site of protests where police fired tear gas on Nov. 2 and 17.
At all nine protest locations in its sampling, HKGETV detected hydrogen cyanide. In four cases, the detected levels reached the maximum warning limit and couldn’t be read.
Hay said that, while a proper determination of health risks from such hydrogen cyanide exposure depends upon the length of time a person is exposed to the chemical, “the data should be a warning that there may be health consequences other than short-term effects linked to riot control agents.”
On Nov. 10 in Tsuen Wan, HKGETV also used a thermal imaging camera to read the temperature of a tear gas canister. The camera reading peaked at 400.5 degrees Celsius (752.9 degrees Fahrenheit).
In a second report, HKGETV analyzed the tear gas residue in three samples picked up from protest sites. One is clearly labeled as manufactured by NonLethal Technologies, a U.S. company. The United States recently passed a law banning U.S. firms from exporting crowd-control equipment to Hong Kong police.
The other two samples aren’t labeled with the manufacturer’s name. HKGETV determined that they matched photos found online of a tear gas projectile and tear gas grenade made respectively by Chinese state-owned defense manufacturers Norinco and Jing An.
The Hong Kong police have previously confirmed that it sources tear gas from mainland China, but refused to disclose the manufacturer details.
HKGETV’s analysis, done in consultation with chemical experts, revealed that no CS residue was found on the two Chinese samples.
Hay said this could mean the combustion happened long enough for the CS to be completely released, or that the combustion temperature was excessively high. He said more testing needed to be done to fully assess the risks.
Eva Fu contributed to this report.
From The Epoch Times