HVAC and FM Contractors can take steps to cut down on airborne transmission
One of the big questions about coronavirus from an HVAC perspective — is how significant of a role airborne transmission plays in its spread.
There is the potential for airborne transmission, and if viruses that are viable are in those droplets that you’re producing from sneezing or coughing, some of them will be small enough that they will stay airborne for a long time. So, it’s not impossible that infectious particles in the air could stay aloft long enough to be collected, in the return grille of an HVAC system, go through the ductwork, and infect someone in a different space.
Because there are three distinct ways of transmitting an infection, even perfect control of airborne pathogens would not eliminate all risk. However by switching off the recirculating capacity of Ventilation systems, and running everything on full fresh air then that option is virtually eliminated
THE FOCUS IS ON PREVENTION
The BESA position on airborne infectious diseases, identifies three methods of controlling airborne infection that have proof of efficacy: ventilation, particle filtration, and UV. You can read about their statement here
Filters
Any air cleaner that removes particles from the air has some potential to reduce exposure to coronavirus. However there has to be clarity on what efficiency of filter is required to be effective enough to have a significant impact on how likely people are to get infected by the airborne route.
Filters are the best way to trap particulates and sub micron contaminants including PM2.5 (particles that have a diameter of less than 2.5 microns),The smaller the contaminant’s diameter, the denser the filter media must be to capture it.
HEPA (high-efficiency particulate arrestance) filters, often used in critical care environments within healthcare buildings, are 99.97 percent effective at trapping particles down to 0.3 microns.
However, Covid-19 is very small, measuring between 0.06 and 0.14 microns in size. therefore even HEPA filters will have some small level of penetration. Only a few percent.
CONTAMINATION CHANCES
While HVAC professionals may be the trusted experts on indoor air quality, they are not the experts on COVID-19,
Even the US Centre for Disease Control (CDC) is trying to understand COVID-19, its transmission, the life of the virus on surfaces, how to treat, and so much more, As stated by the CDC and WHO, there are still many unknowns
Still, the HVAC industry can use current information to draw conclusions about the effectiveness of IAQ products to keep the virus out of the airstream.
UV
UV disinfection systems for HVAC systems complement conventional filtration, by addressing microorganisms that are small enough to pass through filters.
Air filters are designed to capture larger particulates in the air whereas ultraviolet disinfection and airstream UV disinfection are effective at inactivating pathogens, UV germicidal systems have also been shown to reduce microbial load and pathogens that are found within the HVAC system and drain pan that would otherwise be introduced and distributed throughout the building.
Although it may take time to stop the coronavirus spreading externally, UVC emitters can help with your fight inside the building we work in. High output UVC works by destroying the DNA and RNA of microorganisms and is therefore effective against all types of viruses. Studies have shown that even a short exposure to the UVC emitter can destroy the virus. UV disinfection systems is science-based and the technology is backed by this.
HVAC Air Cleaners
These duct air purification systems use the advanced (Photohydroionization) technology, which significantly reduces odours, pollutants, VOC’s, smoke, mould, bacteria and viruses in the Indoor Air. These special HVAC cells are easy to mount into the ductwork of HVAC systems where most issues with buildings systems originate. When the HVAC system is operating, the HVAC- cell creates an advanced friendly oxidation process consisting of hydroperoxides, ozonide ions, super oxide ions, and hydroxide ions. These friendly oxidizers revert back to oxygen and hydrogen after the oxidation of the pollutant.
Some models are suitable for larger spaces, producing up to 40,000 m3 of purified air pro hour.
The AOP cell unit size is scaled to accommodate the various air flow rates of different HVAC systems. Locate the fan capacity of your HVAC system, then choose the model model that corresponds that flow rate.
Here is a video of one system
We also recommend paying attention to a Buildings relative humidity.
The recommendation is to try to keep minimum RH between 40 and 60 %, because viruses are least viable in that range,Many commercial buildings have humidity control to keep conditions in that range, but in winter — especially if it’s old and leaky and in a cold climate —humidity drops down to 20% or lower. A well-maintained humidification system that keeps your RH at the recommended level is a good idea.
While HVAC is part of the disease prevention process, often contractors need to brush up on other, non-HVAC-related strategies to share with their clients too.
Risk reduction involves doing a number of different things, and mechanical additions — like installing higher quality air filters or fitting UV or Air Purification systems into your AHU’s — is not the only thing you should do. Things like hygiene, being careful about whether you touch your face, whether you’re shaking hands with people, whether you’re washing your hands frequently … those, in many ways, are just as important.
