The World Health Organisation (WHO) have recently acknowledged growing concerns surrounding the possible airborne transmission of the coronavirus COVID-19. Australian and New Zealand Medical officials are closely monitoring the outcome of pending investigations, however, there are no changes to current Government recommendations at this time.
Infectious respiratory viruses are typically spread from person to person through close physical contact with one another or through respiratory droplets which are produced when an infected person coughs or sneezes. These droplets may then be inhaled or come into close contact with the eyes, nose or mouth of another person.
Respiratory droplets are very small, often invisible to the eye, with a particle size ranging from less than 0.5 micron to 15 micron. Standard measures to help mitigate these droplets within indoor HVAC systems include:
Providing sufficient and effective ventilation
Supplementing general ventilation with airborne infection controls
Ongoing HVAC system maintenance
Upgrading to higher efficiency air filters, rated F9 or ePM1 85%, is recommended for HVAC systems with AHUs. However, due to increased resistance to airflow and space restrictions, this may not be practical for every commercial HVAC system.
It should be noted that upgrading particulate air filters may also result in:
The next best option is to select the highest-rated air filter your HVAC system can handle, and/or run the system on an economy cycle, with 100% outside air, where possible.
Portable in room air cleaners or air purifiers may also assist with reducing viral load, especially where supplementary localised control is needed.
An interesting US based article, published to the McKinsey and Company website, discusses how modifications to heating, ventilation, and air conditioning systems might help reduce the spread of the coronavirus COVID-19 by purifying air, improving ventilation and managing airflows. The article, written collaboratively by the Advanced Industries Practice was published to the site on July 9, 2020 and is available at the link below.
New Zealand