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Coronavirus: How hard can it be to get the lowdown on face masks?


When face masks sold out in Hong Kong and people started queuing round the block on the back of rumours that new supplies were available, Jack Lau decided to investigate how to reuse the ones he had. He learned a lot about science, and a few things about journalism, too.

People queued up for hours to purchase face masks from a makeshift stall
People queued up for hours to purchase face masks from a makeshift stall

When the first confirmed cases of COVID-19 emerged in Hong Kong, I wasn’t terribly concerned. After all, Hong Kong’s epidemic readiness and personal hygiene practices have improved over those in 2003, when SARS killed 299 people in the city. It would all be over in a few months, I thought, and for now we just need to wash our hands more often and wear masks in public places, as everyone did 17 years ago.

But when people began to queue for hours for masks and their prices soared, it became clear those with few or no masks might have to stay home for months. I was one of them.

Ann Chiang
Ann Chiang

So, I went looking for answers: Could I reuse a mask and still be reasonably protected from airborne droplets containing the virus? And if so, how could I disinfect one for reuse?

Experts and health officials largely advised against reusing masks. Attempts to do so were laughed at and dismissed as unscientific. The most notable case was perhaps that of lawmaker Ann Chiang, who posted a video on her Facebook page she found online detailing how to disinfect masks by steam. Those without surgical masks were told not to leave their homes. The city’s Consumer Council collaborated with the University of Hong Kong-Shenzhen Hospital and made a tutorial for creating a DIY paper mask, but the result was hard to breathe through.

Despite near-unanimous advice against reusing masks, most have ignored the experts. And the “expert” advice was not always convincing. Sometimes GPs, who are users of masks but not experts, were asked about their effectiveness when journalists ought to have asked researchers in environmental health or material science. More problematic was that medical experts and health officials only said in the news what they believed to be the best personal hygiene practices against the virus. Often they gave no explanation, or mixed a bit of science with public policy considerations.

When Ho Pak-leung, clinical associate professor at the University of Hong Kong’s microbiology department, criticised Chiang’s steam disinfection tutorial video, some Chinese-language media only quoted soundbites saying the video was “fake news” and “outrageously wrong” – but didn’t explain why.

Screen capture of the video shared by Ann Chiang on disinfecting masks by steam
Screen capture of the video shared by Ann Chiang on disinfecting masks by steam

Ho’s email to AFP Fact Check was more informative. He said the crux of the matter was not if viruses can be killed during disinfection, because surgical masks are meant to be single-use. As a reader, I found this unconvincing. Whether the mask is designed to be single-use or whether they can be used multiple times are different questions. In the same AFP story, Ho added attempts to disinfect single-use masks might harm their effectiveness, without pointing to any evidence.

In an interview with the Hong Kong Economic Journal, Andrew Wong, president of the Hong Kong Society for Infectious Diseases, cited a 2006 report by the Institute of Medicine in the U.S. that he said discouraged reusing masks and respirators. But that report did not provide evidence. Its authors only spoke to mask manufacturers and said they had to rely on their collective judgment due to severely limited data.

Given the lack of evidence presented by experts in the news, I spent days scouring my university library and databases for literature on reusing masks and respirators.

A 2015 study conducted by the United States’ National Institute for Occupational Safety and Health published in the Journal of Occupational and Environmental Hygiene concluded short-wavelength ultraviolet light can disinfect N95 respirators with only a small decrease in effectiveness, although the masks degraded at higher doses of ultraviolet light. The study concluded the tested N95 masks could be reused a limited number of times.

Hong Kong’s epidemic readiness has improved since the SARS crisis in 2003
Hong Kong’s epidemic readiness has improved since the SARS crisis in 2003

A study published in February from Fudan University’s molecular virology lab concluded blow-drying surgical masks for 30 minutes can significantly reduce the presence of virus without much damage to their ability to filter particles at 2.5 microns, which are smaller than droplets that might carry viruses.

Jack Lau
Jack Lau

In the first few months of the epidemic, the media could have better bridged the disconnect between experts and laypeople on reusing masks. From what I have read, this area lacks research. It is inconclusive whether masks can be reused, but from reading the news I had the impression that reusing masks went against scientific evidence.

I am not advocating that you reuse your masks or don’t reuse them. I am arguing that experts should not overstate how informed by science their decisions are. Health guidelines can also be informed by public policy, such as preventing panic and ensuring the health system has a steady supply of masks. And it’s important that journalists make both considerations clear.

Journalists should also not write as if readers trust interviewees by virtue of their job titles and expertise. Journalists should give them the chance to justify their views, but with a healthy dose of scepticism. This means experts should be expected to produce solid evidence to support their claims. Journalists should report not only the what but also the why.

Otherwise distrust between people and authorities, medical and others, can flourish. Such distrust is already a problem in Hong Kong due to months of political unrest that has soured the government’s relationship with civil society. Distrust is not exclusive to Hong Kong. Public health policies from Iran to the World Health Organization are being challenged. By being a bit more inquisitive, journalists can keep people better informed at a time when communicating science is critical.

People queued up for hours to purchase face masks from a makeshift stall

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