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“HEY GWEILO, too poor to buy a mask?” Such handwritten signs around Hong Kong are evidence of growing impatience with foreigners who insist on going out in public without face masks during the coronavirus crisis (gweilo, meaning “ghost man", is slang for a white person). It’s a well-aimed barb—most foreigners in Hong Kong have the money to buy a pack of disposable face-covers. And Hong Kongers these days are scrupulously hygienic. Even before the latest pandemic, lift buttons were sterilised hourly and waitresses would set extra chairs at restaurant tables so your bags do not touch the floor.

Hong Kong was scarred by the SARS pandemic, caused by another coronavirus, in 2003. It killed about 300 people in the territory. Perhaps because of that experience, Hong Kong has coped better than most countries with the covid-19 contagion that is paralysing the world. Its government responded quickly by closing schools and public facilities, and encouraging people to work from home but stopped well short of the sort of lockdown enforced in other parts of the world. Only four people have so far died of the disease.

Initially Hong Kongers blamed mainland Chinese for carrying the disease from across the border. They demanded, and partly obtained, the closure of the frontier. Then the main concern became local transmission among Hong Kong residents, which was swiftly brought under control. For six weeks the graph of cases in Hong Kong was enviably flat. Since mid-March, however, the line has shot upwards. The spike is caused mainly by “imported” cases of travellers infected abroad.

In the week ending on March 27th the number of new cases more than doubled, to 518. Around three-quarters of recent infections involved people with a history of travelling abroad. Many are now being identified on arrival at the airport. Most are Hong Kong residents, including students studying in the West. Many families who fled Hong Kong when things seemed risky rushed back before March 19th to avoid the fortnight of mandatory quarantine which the government now demands of all arrivals.

After the SARS crisis, Hong Kongers never lost the habit of wearing masks in public when sick. And when covid-19 struck, people queued for hours to buy handfuls at extortionate prices. So many packages of masks used to arrive from abroad that the postal service made special arrangements for their speedy delivery. Now the masks are shipped the other way: Hong Kong’s postmen are laden with piles of parcels full of masks waiting to be dispatched to coronavirus hotspots around the world.

The Hong Kong government advises wearing a surgical mask if you are ill, travelling or visiting crowded places. But many people wear them everywhere. Others sport industrial-style respirators with rubber seals. Some café owners, bus drivers and, oddly, all bookmakers ask customers to wear masks, but it is rarely mandatory outside hospitals and doctor’s surgeries.

Confrontations with foreigners who go mask-free are rare, but the stigma is growing. The fact that the worst of the pandemic has shifted to Europe and America reinforces the suspicion that foreigners do not take the crisis seriously. Discussions online often suggest that bare-faced Westerners become infected through their own negligence. Outraged local newspapers run photographs of Westerners socialising without masks. On March 16th a video of a white man removing his mask on a train, licking his finger and wiping a handrail caused justifiable fury. The American hedge-fund manager in the film claims it was a joke but online commentators called him “white trash”; some demanded his deportation.

Until now the “expats” who congregated outside bars without masks were flouting norms on social distancing but not the law. A cluster of cases linked to bars and musicians prompted the territory’s leader, Carrie Lam, to threaten a ban on places selling alcohol, which she blames for unhygienic “intimacy”. Instead, she announced restrictions on the number of people in restaurants and a ban on public gatherings of more than four people, starting on March 28th.

Not all residents adhere to stereotype, of course. Some Chinese Hong Kongers don’t wear masks; increasing numbers of Westerners do, and admonish those who don’t. A social-media campaign telling people to #WearAFuckingMask was set up by an American resident.

Those who choose not to wear masks can point to official advice from their own governments. The World Health Organisation recently tweeted that “if you do not have any respiratory symptoms [...] you do not need to wear a medical mask”, claiming that they may provide a “false feeling of protection.” Even Hong Kong's government for a time asked people not to wear masks because of shortages. But officials these days are rarely seen without one.

Ordinary Hong Kongers are fed up with being told that the science behind mask-wearing is disputed. They look at neighbouring east Asian countries, where people wear masks routinely, and notice that they are coping with the disease relatively well. Many factors are at play. But the ubiquity of the mask is one reason. This not just because of its ability to block germs, or prevent people from touching their faces. It is also a means of building trust and fostering civic responsibility—a visible signal to fellow citizens that you are doing your bit to protect them and they should do theirs. If you won't bother to wear a mask, who knows whether you bothered to wash your hands?

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