Some Recommendations for Buildings in the Era of COVID – a Conversation with Dr. Peng Xu

Peng Xu is a professor at Tongji University, and an entrepreneurial business person in China. He is also my first PhD student at The University Colorado Boulder.  Peng worked on the germicidal UV research we did with funding from the CDC and that has been used to inform guidance to hospitals. It is also gaining interest again with the COVID pandemic, as germicidal UV is one of our engineering tools to keep indoor environments at lower risk for infection.

Peng’s been working hard to inform policy and learn from experiences in China on the topic of what should be our best practices in buildings. I recently viewed some slides from a talk he gave and then we talked over the phone, and here are some of the things that he shared with me.

  • Home quarantine doesn’t work. 83% of those who got sick in China were infected from in the home by relatives. A better practice would be to stay in a converted temporary quarantine shelter until you’re better.
  • Everyone needs to wear a mask. And especially inside buildings.
  • Windows need to be opened in buildings (but many US buildings don’t have operable windows).
  • Toilets play a big role. Field measurements in Wuhan have shown that airborne coronavirus concentration is highest in the bathrooms (both public bathrooms in a mobile cabin hospital and in ICU private bathrooms), so the recommendation is to use a private toilet and to limit the usage of public toilets to the public. (Note, I don’t know how that’s going to work at CU Boulder when it starts to reopen!)
  • Unhealthy individuals need to be kept out of buildings. how can we do this? It’s important to check temperatures. Granted younger people don’t often present with elevated temperatures, but this could keep at least 50% of unhealthy people out of buildings where transmission is more likely to occur. Also, it would be good to have a way to check whether the person has been exposed – contact tracing would do this, maybe with an app.
  • Fan filter units, such as a HEPA recirculating portable air cleaner, are important to use in high risk or high-profile areas such as crucial offices. They must be sized appropriately.
  • In buildings, turn off the return fan, or use a MERV 16 or higher in the return.
  • Note that 3,062 doctors and nurses were infected in Wuhan. However, most of them were from local hospitals because they did not have adequate PPE at the beginning. During the outbreak an additional 42,600 doctors and nurses were sent from other provinces to help Wuhan, and none of them got infected because of the excellent PPE they were wearing.
  • Where are you take off your PPE and how is important. This activity has a very high rate of virus shedding so spray the PPE with alcohol before taking them off.