In an interview with Astro Radio, Professor Dr Victor Hoe answered some of the issues of ventilation in the workplace
Why is ventilation at the workplace important in lowering the risk getting infected with Covid-19?
Ventilation forms a very important component in the control of the COVID-19 infection at the workplace. This is because the SARS-CoV-2 can be transmitted from an infected person through droplets and aerosols. The aerosols generated while a person’s sneeze, cough, sings, or talk loudly can travel for a substantial distance of up to 8 metres from the source. It also can remain in the air for minutes to hours depending on the ventilation. It is important for us to be able to remove the contaminated air quickly by increasing the air exchange or using an air filter to clean the air. That is why, since the start of the pandemic public health experts have advised us to avoid crowds, confined spaces and close conversation.
What would be considered as good ventilation and bad ventilation?
It is difficult for a layperson to know if the ventilation is good or bad as we cannot see what is in the air. However, there are some basics that we can use to get a rough idea if an area has good or bad ventilation.
The first thing is fresh air is always better, so if a room has wide open windows or open doors on the opposite side of the room than it is a sign that the room has fresh air. However, it is not practical or possible for an area to have an open window all the time. This could be due to the design of the building, or the external environment is contaminated.
So, the second-best thing is to be in a room with a centralised air conditioning system. Centralised aircon take in fresh air from the outside and condition them before distributing to the room. The air in the room with a centralised aircon will be replaced with fresh air routinely. For example, in an office or restaurant, the air in the room will be replaced completely with fresh air every hour. In an operating room in the hospital, the air is refreshed every 15 minutes.
However, in a room with a split unit aircon, for example, those that are found in most homes and offices, there is usually no fresh air from the aircon. The air in the room recirculated. So, to improve the air in the room, if possible, is to leave the windows or doors open a little while we are in the room to allow fresh air into the room.
The other way for us to judge if the room has good or bad ventilation is to smell the air. If it smells bad that means it has bad ventilation.
Most of us work in building with air conditioning, some dont even have proper windows.. so what should we do?
If you work in an office without proper windows, the first thing you need to know is if the office is supplied with a centralised or split aircon unit. If it is a centralised aircon then is not a big problem, as there is fresh air coming from the aircon system. However, if your office uses a split air con unit, then there are two things you can do.
- to keep the office door open to allow fresh air from the outside, or
- to install a portable HEPA or high-efficiency particulate filter system or people called it air purifier with a HEPA filter in the room. Please ensure that the filter in the air purifier is of HEPA standard, i.e., at least H13 and above.
What measures should be put in place to make employees feel safe to return to work again?
The important thing for an employer to do is to conduct a risk assessment of the workplace. They need to ensure the maximum number of people for a given space based on the type of work and ventilation system. The employer needs to develop a standard operating procedure that will minimise the transmission of the disease in the workplace based on the risk assessment results.