Since the outbreak started last year, masks, disinfection, social distancing regulations and
hand sanitisation have been the main protective measures recommended by Hong Kong authorities. These measures have been effective as Hong Kong has time and again dodged the bullet of a mass outbreak, but it has never been able to shake off the virus completely as local transmissions continue to pop up.
As the number of new cases wanes, authorities have allowed restaurants, gyms and other businesses to reopen with strict safety guidelines. Bars and karaoke establishments are also
reopening. Over time, commercial activities have returned and office workers are again commuting to their workplaces, leading to crowded bus and trains.
After a cluster broke out at
Mr Ming’s Chinese Dining restaurant in February, the government ordered all catering units to ensure their premises had at least six air changes per hour or install air purifiers to make sure stale air was removed as customers were not wearing masks during the time they were there.
Owners of small and medium-sized restaurants have urged the authorities to give them more time, saying they will not be able to foot the bill for re-engineering their premises or buy air purifiers as they have struggled for a year with pandemic restrictions. Professor
Yuen Pak-leung, who is an adviser to the government, has said restaurants can apply for more time to make the alterations if necessary.
This is puzzling, especially given the alacrity of officials in ensuring compliance with social distancing rules when
domestic helpers gather in open areas, keeping picnic sites in country parks and children’s playgrounds cordoned off even though no clusters have been linked to outdoor activities.
Given that major outbreaks in Hong Kong have been linked to bars with
live bands,
dance halls,
restaurants and gyms, ventilation in buildings needs to more rigorously monitored. Crowds mill around inside malls, office workers have returned to their workplaces and schools have started direct contact classes, and all of these involve closed spaces where air is recirculated.
The guidelines of the United States
Centres for Disease Control and Prevention, which Hong Kong authorities also consider, say inadequate ventilation or air circulation allows a build-up of suspended small respiratory particles. These are “often generated with expiratory exertion” such as shouting, singing and exercising.
Dr Siddharth Sridhar of the University of Hong Kong’s Department of Microbiology says focusing on transmission through droplets alone is an outdated model.
Airborne transmission is a worry, and the Hong Kong public’s adherence to
wearing masks and hygiene are key reasons for keeping the virus at bay, he says. Even though trains and buses are also crowded, the air is not static like the inside of buildings or even some MTR stations.
One of the authors of the Lancet study, Oxford University’s Trish Greenhalgh, says holding back measures to check airborne transmission of the virus on the pretext that experts are divided on such findings is a “dangerous trope”. She says along with the vaccination drive, crowd control measures should be implemented in places such as shopping centres where air is recirculated.
In the Lancet article, Greenhalgh and others argue that although other transmission routes can contribute, the airborne route is likely to be dominant and the “public health community should act accordingly and without further delay”.
Given such warnings, Hong Kong should proactively implement air circulation regulations for buildings and ease up on other measures to allow more outdoor activities.
Hari Kumar is a journalist based in Hong Kong since 2003
