Air must circulate well everywhere

PETALING JAYA: Health experts have warned of the danger of Covid-19 being spread via air-conditioners, and have called on restaurants and workplaces to ensure there is sufficient air circulation in the premises.Universiti Malaya virologist Prof Dr Sazaly Abu Bakar said restaurants that allow dine-in must ensure proper directional airflow from air-conditioners.

“This means either it sucks the air up or you have the air flowing in one direction. Unless restaurants can do that, I won’t advise them to reopen, especially so for closed-door restaurants, ” he said.

Dr Sazaly said it was too dangerous to reopen for dine-in service as air-conditioning in a closed-door restaurant would circulate infected air in the premises.

However, he noted that for open-air restaurants, a good ceiling height that allowed good air circulation was sufficient.

“To practise social distancing, make sure that not too many people are seated at the same table, ” he said, adding that customers were considered seated too close to one another if they could smell each other’s breath.

In a research letter by a group of Chinese scientists in Guangzhou, China, titled “Covid-19 Outbreak Associated with Air Conditioning in Restaurant, Guangzhou, China”, it was found that nine people from three families who had eaten in the same air-conditioned restaurant were infected by the virus (see graphic).

The research published in the Emerging Infectious Diseases Journal based at the US Centres for Disease Control and Prevention in April, showed that the index patient and his family were sitting in between two other tables for lunch on Jan 24.

The families at the table in front and behind the index patient were infected by the virus.

The research pointed out that droplet transmission of the virus from the index patient, who was asymptomatic at the time, was due to the direction of the airflow.

“We conclude that in this outbreak, droplet transmission was prompted by air-conditioned ventilation. The key factor for infection was the direction of the airflow.

“To prevent the spread of Covid-19 in restaurants, we recommend strengthening temperature-monitoring surveillance, increasing the distance between tables and improving ventilation, ” the research noted.


As Malaysians slowly return to work under the conditional movement control order (MCO), Dr Sazaly said companies too must ensure they were observing all the Health Ministry’s standard operating procedure (SOP) and ensure there was proper air circulation in the workplace.

“Knowing what had happened in that restaurant in China, proper air circulation is very important and critical.

“Proper air exchanges means whatever air that is in the restaurant or the workplace must be sucked out. If the air is recirculated, the air must be treated, ” he said.

Former deputy health director-general Prof Datuk Dr Lokman Hakim Sulaiman said the article by the Chinese scientists suggested that the droplets could have been carried further than expected (1m) by the air current of the air-conditioner.

Unfortunately, he said there were no other details given about the air conditioner’s system such as the fan speed or whether it was a split unit.

“It is all about risk. As long as Covid-19 is still around, the risk of infection is there. The risk will become zero when there are no more cases of Covid-19.

“Therefore, in Malaysia, there is still the risk of getting infected. But, the risk is lowest in green zones and highest in red zones.

“Likewise, air conditioned restaurants in green zones have lower risk than in red zones.

“A premises with centralised air-conditioner is less risky than one with split air-conditioner units, ” he said.

Dr Lokman said restaurant owners could reduce the risk of infection by ensuring its employees were free of infection, reducing the density of people dining in, disinfecting frequently touched surfaces often and ensuring no tables were directly under the air-conditioner vent.

He added that it was also important to ensure spaced-out sitting, maintain a diners’ register for contact tracing and ensuring all employees wear a mask at all times.

“There is no guarantee that it is fool-proof but it minimises the risk.

“If you want to dine out, it is about assessing the risk, whether your area is Covid-19 free, type of air-conditioning system, measures taken by owners and the customers’ own social responsibility, ” he said, adding that the elderly and the sick should stay at home.

Dr Lokman said buffet dining was riskier than having an ala carte meal.

Universiti Putra Malaysia medical epidemiologist and biostatistician Assoc Prof Dr Malina Osman said the possibility of transmission of the virus in poorly ventilated areas and poor social distancing practices exist.

She advised restaurants to ensure a standard distance between customers.

“Tables and chairs should be arranged according to the suggested measurement.

“If the restaurant has permanent tables and chairs, then the distance still needs to be maintained by not allowing seating at certain table and chairs, ” she said.

She said in a workplace environment with indoor air-conditioners, seating should also be one metre apart, adding that it was important to make sure that the area had good air ventilation. Apart from that, Dr Malina said employees should always wear a mask and maintain good hand hygiene.

“If all these are in place, the risk to contracting the virus would be low, ” she said.

Dr Malina also suggested that meetings in closed settings be held for not more than 15 minutes.

“The participants should avoid unnecessary talking and discussion, ” she said.

She added that if employees were able to work from home or if meetings could take place via a virtual setting, that would be a better option.

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