WHO recommendation to businesses
The WHO recommends that an air purifier should be used to close the gap between the minimum litres per person per second requirement for purified air and what any existing ventilation provides. Companies can add portable air purifiers with HEPA air filtres, without affecting the fabric of the building.
Working in tandem with HVAC systems, these can easily provide the optimum cumulative air change per hour rate.
Schools
Implementing a building-wide solution can be problematic for many schools that have ageing ventilation systems and lack the funding for comprehensive system overhauls. Under these circumstances, portable air cleaners with HEPA filtration are recommended.
Portable HEPA air purifiers are indeed a fraction of the cost of integrated HVAC systems and can be installed immediately, with no disruption.
They also add value through multi-tasking, not just trapping viruses like COVID-19 but also bacteria, allergens, mould spores, and toxic particles.
HEPA filtration
A 2010 NCBI report on the role of particle size in aerosolized pathogen transmission reported individuals with infections producing particles between 0.05 and 500 microns.
The efficacy of HEPA filtration has been proven at 100% with particle sizes of 0.05 microns and smaller, as well as above 5 microns. More importantly, at the 0.3 microns size, the most difficult to catch given their airborne behaviour, HEPA achieves a minimum performance of 99.97%.
The diameter of the SARS-CoV-2 virus has been found to range between 50 nm to 140 nm, or 0.05 to 0.14 microns, and research by NASA proves that HEPA filters are most efficient at capturing ultrafine particles below 0.3 microns in size, as well as larger particles.
The larger sizes are arguably more important as the virus is carried in airborne aerosol droplets, over 10 microns in size, that protect it from evaporation.
HEPA and the UV-C light spectrum source
Having trapped the virus, it must then be destroyed.
A recent study by the Henry Ford Health System shows that UVC light is effective for killing Covid-19.
The SAGE committee provides that in its November 2020 report on air-cleaning devices to combat SARS-CoV-2 transmission.
For prevention of airborne SARS-CoV-2 transmission, the SAGE Committee recommends a combination of two technologies in air-cleaning devices:
SAGE also notes that additive technologies, which add constituents to the air to remove particles, inactivate microorganisms, and/or react with chemical contaminants, have a limited evidence base that demonstrates effectiveness against SARS-CoV-2.
Such technologies – including ionisers, plasma, chemical oxidation, photocatalytic oxidation, and electrostatic precipitation – may also generate undesirable secondary chemical products that could lead to health effects like respiratory or skin irritation.
Humidity
The Centre for Disease Control and Prevention found that 70–77% of flu virus particles could still cause an infection one hour after a person coughed when the humidity is only 23%. When humidity was raised to 43%, the percentage of infectious particles was reduced to 14%.
When humidity is too high, on the other hand, mould can grow in your office, which not only looks unsightly and unprofessional but also triggers allergies and eczema.
Indoor air in the workplace is improved by mitigating virus particles when humidity is low and mould when humidity is high.
Maintaining 30-60% humidity levels is recommended for the healthiest environment.
RENSAIR: hospital-grade air purification system
The Rensair air purification technology was originally developed more than a decade ago for Scandinavian hospitals meeting strict requirements.
The patented engineering of Rensair incorporates a high-power UVC light placed in the centre of a cylindric HEPA13 filter.
Rensair captures and destroys viruses, bacteria, and mould spores and cleans the air from particle pollution.
This is backed by comprehensive data from independent laboratories including:
The key features of RENSAIR:
- Hospital-grade components, including HEPA13 filter and ozone-free high-power UV-C light source.
- Large air processing capacity of 560 m³/hour (20,000ft³/hour).
- We recommend using one Rensair for every 120m² (1,250ft²) of interior floor space
- Built-in particle counter can automatically adjust airflow based on impurities in the air.
- Minimal maintenance required, 9,000 hours (~1 year) of continuous run time before any service is needed
- Requires no installation
Where has it been used?
Rensair in the UK has been used by NHS, PepsiCo, GlaxoSmithKline, Morgan Stanley, CBRE and many other organizations. Some case videos:
- King’s College School, Wimbledon, UK
- Purple Dragon Playroom, Chelsea, UK
- The Prince Charles Cinema, UK
- Lytchett Minster School, UK
- Miami City Hall, USA
Great news for those looking to secure their health while they work in offices and workspaces. During this pandemic and in the future.
