Detecting COVID-19 Virus in Built Environments

Name and Constituency of Member of Parliament
Dr Tan Wu Meng
MP for Jurong GRC

Question 84
To ask the Minister for Health (a) what capabilities exist for detecting the presence, viability and infectivity of the COVID-19 virus in built environments, including in air and on surfaces which members of the public or staff may come into contact with; and (b) whether these tests have been applied to at-risk settings including urban hotspots and Changi Airport's terminals and, if so what are the findings.

Written Answer

To address the risk of COVID-19 transmission in build environments, MOH works with the National Environmental Agency (NEA), which has capabilities for environmental testing, including waste-water, air and surface testing.

NEA has carried out air and surface sampling to detect virus genetic material for epidemiological investigations and research purposes. For enclosed spaces like rooms, viral RNA was detected after it was occupied by infected persons.

But for public spaces, there was no such detection, partly due to the transient nature of human traffic. As such, air and surface environmental sampling is not used for routine surveillance. On the other hand, is waste-water testing is very useful for surveillance. Waste water testing picks up COVID-19 viral fragments that are shed in human faeces into the sewer system.

It is useful and effective mainly in residential settings, such as dorms and HDB blocks. It has been successfully used for HDB blocks in recent hotspots, and positive signals from wastewater testing were followed up with PCR testing for residents in the affected blocks.

As Changi Airport is not a residential setting, wastewater testing is less useful. Further, any positive signals at Changi Airport could be due to travellers or visitors to the airport, in addition to staff. We therefore rely on Rostered Routine Testing of staff for early detection of asymptomatic cases. NEA, BCA and MOH have also issued guidelines on regular cleaning of high touch points and improved ventilation, which will complement mask wearing and safe distancing in reducing the risk of transmission in public spaces.