Scientists from Guangzhou have released recommendations for restaurants after conducting a study that explored how air conditioning in an establishment contributed to an outbreak of Covid-19 in the city.
The scientists researched a coronavirus outbreak, occurring earlier this year, which involved three family groups. All three families had dined in the same air-conditioned restaurant in Guangzhou, before 10 of them fell ill.
The study was approved by the Ethics Committee of the Guangzhou Center for Disease Control and Prevention, and carried out by J. Lu, K. Li, C. Xu, W. Su, C. Yu and Z. Yang from the Guangzhou Center for Disease Control and Prevention and J. Gu, Z. Lai, D. Zhou and B. Xu from the Guangzhou Yuexiu District Center for Disease Control and Prevention.
One family was found to have travelled from the city of Wuhan, where the coronavirus was first identified in December 2019.
The three families dined at the restaurant on 24 January for lunch. One member of the family that travelled from Wuhan began experiencing symptoms of the coronavirus later that day. By 5 February, four members of the person’s family were infected. Two other families sat on neighbouring tables and three members from one family and two members from another also became infected with Covid-19.
The scientists reported that the restaurant was a five-storey building, which was air-conditioned but had no windows. The third-floor dining area, where the families were seated, occupied an area of 145 m2 , tables were spaced around one metre apart, and each floor had its own air conditioner.
The scientists concluded that the outbreak “cannot be explained by droplet transmission alone”. They said that “strong airflow” from the air conditioner meant the droplets were able to travel larger distances than would normally be expected.
As a result, the study found that the droplet transmission “was prompted by air-conditioned ventilation” and that a key factor of this infection was “the direction of the airflow”.
The study advises restaurants, when they are allowed to reopen, to invest in better “temperature-monitoring surveillance”, to increase the distance between tables, and improve ventilation.
The study can be read here.