It is no secret that the Chinese produced CS (tear gas) munitions recently employed by the Hong Kong police are more dangerous than the munitions produced in the West and employed at the beginning of the democracy protests. But what is less known is exactly why this is the case.

The real danger of CS munitions is the result of poor build quality and quality control by the manufacturers, which cause the submunitions to burn at dangerously high temperatures. This causes a far greater risk of inducing serious burns in targets, combusting upon impact, and degrading the CS into far more dangerous compounds.

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Photo: Studio Incendo.

In the case of the Norinco NF01, a 38mm CS round produced on the Chinese mainland, magnesium and aluminium power are used as accelerants to aid combustion. Both of these serve to raise the temperature of the submunitions to 500°C or higher after being discharged. These temperatures degrade the CS gas discharged by the submunitions and release poisonous carcinogenic dioxins.

This temperature alone makes the submunitions dangerous if touched, and hot enough to burn through asphalt. And chemical analysis of spent NF01 cartridges shows that the carcinogens within also include cyanide gas.

The danger of this cartridge has also been demonstrated by its use in other countries. In October 2008, the munition resulted in the deaths of several protestors in Bangkok, Thailand, and the Thai authorities destroyed their entire stockpile in response.

The Jing An KF-302-20 is a CS grenade that Hong Kong police began to purchase last August to replace their rapidly diminishing stocks of British N225 Rubber Bursting CS Grenades, which were no longer available for purchase after the British government revoked the manufacturers export license in June of the same year.

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A tear gas grenade used by the police. Photo: Holmes Chan/HKFP.

The KF-302-20 has all the same chemical and thermal dangers of the NF01 previously discussed, heating up to 3000°C during combustion in confined, laboratory conditions and reaching 500°C in normal usage, and also produces cyanide gas as a consequence.

On November 2, a volunteer medic standing at the Percival Street Tram Stop in Causeway Bay suffered third-degree burns after a submunition fell down his back and ignited his shirt.

This danger of ignition poses another danger, as attempting to extinguish the flames with water will produce hydrogen, and risks causing a second detonation of the submunition. The KF-302-20 is also excessively loud at detonation and could cause permanent hearing loss.

The KF-302-20 also has very unreliable fuses and often detonates early. The manufacturer claims that it detonates 1.2 seconds after release, but examples have been documented detonating as early as 0.5 seconds after release. This makes the control of the munition far more difficult, and subsequently dangerous.

Indeed, while certainly “less-lethal,” CS is far from non-lethal even when manufactured correctly, as user error by the operator can still create the potential for lethality.

Early in the protests, when the Hong Kong Police Force exclusively used American manufactured NonLethal Technologies MP-6M5-CS 38mm cartridges, and British manufactured N225 Rubber Bursting CS Grenades, which both burn at a low enough temperature to not degrade into cyanide gas nor combust on impact, the munitions were still employed in dangerous manners that endangered the protestors and civilians they were fired at.

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Riot police fire tear gas rounds into the air outside the government’s headquarters. Photo: Holmes Chan/HKFP.

In particular, CS gas should not be fired indoors, as ventilation is required to prevent suffocation. This guideline was infamously disregarded by the Hong Kong police on August 11, when CS gas was deployed inside Kwai Fong Metro Station.

CS munitions also should not be fired directly at the head, as the submunitions are powerful enough to cause kinetic (impact) damage , and hot enough to cause thermal damage (burns). Notably, this guideline was disregarded on August 5 and 11 when Hong Kong police fired CS munitions at protesters from rooftops, which guaranteed hits to the head.

George Colclough is an arms researcher who primarily focuses on Asian munitions and conflicts. He has researched and published on a variety of contemporary and historical conflicts, as well as weapons proliferation across Europe, the Middle East and Asia.