by Kimberley Graham, Green Restoration Ambassador
This winter in the northern hemisphere, proper ventilation is more important than ever, particularly in light of the COVID-19 pandemic. Ventilation is a way to purify the air and reduce the number of virus particles. There are two important aspects of healthy ventilation: fresh air and disinfectant.
COVID-19 in Indoor Spaces
Inside commercial and residential buildings there are three transmission pathways for COVID-19:
- 1-2 m close contact from the combined droplet and airborne droplets and aerosols emitted when sneezing, coughing, singing, shouting, talking, and breathing;
- long-range airborne (aerosol-based); and
- surface contact through hand-hand, hand to the surface, etc.
Adequate and clean ventilation is tackling the first two transmission routes within indoor spaces, both close contact and long-range airborne transmission.
The Importance of Fresh Air
By adding clean and fresh air from outside, the potentially infected indoor air is diluted and displaced inside the building. This is not only true for COVID-19, but also for many other infections such as the common cold and flu. The more often a room is ventilated each day, the cleaner the air becomes.
According to the Environmental Protection Authority (EPA) fresh air may enter an indoor space in three main ways:
- through natural ventilation, such as through windows and doors;
- through mechanical means, such as through outdoor air intakes associated with the heating, ventilation, and air conditioning (HVAC) system; and
- through infiltration, a process by which outdoor air flows through openings, joints, and cracks in walls, floors and ceilings, and around windows and doors.
Maximum ventilation in indoor spaces is an important factor for staying healthy throughout winter, even though opening the windows or doors may not be the natural tendency when it is cold. The number of times the space should be ventilated with fresh air depends primarily on the size of the space together with how many people are sharing the space. In a small indoor space with only one or two people safely socially distanced, it may only be necessary to open the window a few times each day. For larger spaces, with a lot of people safely socially distanced, it may be advisable to open the windows at least once per hour.
When ventilating indoor spaces during winter, it is always a good idea to consider the overall energy efficiency of the building.
Cleaning and Disinfecting HVAC Systems
It is important to clean and disinfect HVAC in commercial and residential buildings more regularly during winter in light of the pandemic. Contaminants found in HVAC systems may contribute to mold or mildew (fungal growth) and other microbiological growth. Other contaminants may include debris from outside air sources, such as fire damage residue, dust, or from vermin. Air conditioning systems use heat exchangers to cool or heat the air to a comfortable level before the air is distributed throughout the ventilation ducts. Although this creates a pleasant atmosphere and temperature to live or work, it can also create a refuge for viruses and pathogens.
If you are unsure when the vents or filters were last cleaned in your building or home it is probably a sign that it is time to get it done. It is recommended to clean and disinfect HVAC systems at an interval of once per quarter during the COVID-19 pandemic. There are three main defences to clean and disinfect HVAC systems, which will be outlined below.
- Natural Chemical Cleaning
The dust and debris build up in HVAC systems, particularly inside filters and vents, should be cleaned regularly. We use plant-based chemicals, such as Benefect or Envirocon, which are not toxic to human health.
- UV-C Light
Germicidal UV Lights are known to kill viruses as well as being a disinfectant for air and surfaces. UV-C has been used extensively for more than 40 years and can help to mitigate the risk of infection of a range of pathogens. Germicidal lamps are known to be extremely effective in breaking down the DNA of viruses, such as COVID-19, which means that they cannot replicate.
- HEPA Filtration Systems
Portable air purifiers are beneficial when ventilation is not possible or adequate enough. Also known as air-sanitizers, air purifiers are designed to filter the air in a single room, not the entire building. Studies have shown that air purifiers with HEPA filters reduce 50 percent or more of the particulate matter found in the air.