Lousy IAQ Analysis

Restaurants in Hong Kong must comply with the relevant provision of the FEHD licensing requirements. For Air-conditioned restaurants, typically the indoor air is largely recirculated with a small quantity of fresh air / outdoor air added into recirculating air steam.

By law, the minimum requirement is provided in clause 42 of the licensing requirements, only 17m3/hr/person (or 4.2 litres/sec/person) [1] of fresh air / outdoor is required, to put that into perspective that rate is lower than the normal 7-10 litres/sec/person rate.

Of course, the result is poor IAQ quality, because the air pollutants, including airborne covid19 [2] concentrations, are diluted extremely slowly.

“Poor ventilation may play a major role in transmission” RTHK reported the spread of covid19 investigation [3]. However, as explained above, it is no surprise, all Hong Kong restaurants have little fresh air/outdoor air, thus are poorly ventilated, and any bacteria/virus in the air is not diluted.

[1]https://www.fehd.gov.hk/english/howtoseries/forms/new/A_Guide_to_Restaurant.PDF#page=31 
[2] http://www.kelcroft.com.hk/20200404-news-covid19.htm
[3] https://news.rthk.hk/rthk/en/component/k2/1537915-20200715.htm