Poor ventilation in enclosed spaces increases the risk of spread of Covid-19, according to a University of Hong Kong study. Restaurants, bars, nightclubs, buses, trains, taxis, anywhere there is not enough airflow the danger rises.
The study was led by Professor Yuguo Li of the HKU Building Environment Department. Professor Li and his students found the virus can be transmitted several metres by air when there is poor ventilation. They made a detailed study of three outbreaks in crowded situations looking at where infected individuals were located, who they infected and the rate of ventilation. The cases studied were at a Guangzhou restaurant, two Hunan buses and the Diamond Princess cruise ship.
Prof. Li Yu Guo Photo: HKU
At the GZ restaurant, three families who did not know each other were sitting at adjacent tables. An infected person sat at one table and spread the disease to nine people at all three tables, including one person 4.6 metres away. The ventilation rate in the restaurant was only one litre per second per person. The international standard is five litres per second per person.
Similarly, Professor Li found, the Hunan buses were poorly ventilated. One person with covid took a bus ride of over three hours that led to seven people being infected. The furtherest person infected was 9.5 metres away. The bus’s ventilation rate was only 1.7 litres per second per person.
Public places should enhance indoor air ventilation and social gatherings should be avoided if there is insufficient ventilation. A carbon dioxide sensor could help indicate poor ventilation if the reading is more than 1000 parts per million. Otherwise, Professor Li said, “a simple criterion for insufficient ventilation is if you can smell other people’s breath from a distance.”
The is article is abbreviated for length. You can see the full story from the University HERE.
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