Air purification vs air sterilisation, what you need to know

5 minute(s) to read

With many air cleaning systems on the market today, it can be overwhelming to choose which one is best for managing and maintaining air quality.

What should you look for in a system? And should you go for an air steriliser or air purifier – what is the difference?

Addressing ‘re-circulated air’

“Whether we are working in an open-plan office, going to a restaurant, going for groceries, or staying in a hotel, what comes to mind now is the Indoor Air Quality (IAQ) in that environment,” says Stephen Harkin, Managing Director of Shiva Air Conditioning, a Dublin-based company who are experts in commercial air conditioning installation and maintenance.

“People may assume that if they have ventilation or air conditioning systems, or they are keeping their doors and windows open, they are safe from germs and bacteria. But this is not a correct assumption.”

Stephen says to-date, a lot of emphasis has been put on products that sterilise the incoming air, some of which are very expensive. “But think about it: why would you sterilise incoming air from the outside environment? Why is it called fresh air in the first place if it requires sterilisation?”

According to Stephen, the main culprit to be addressed in the workplace, hospitality, leisure or retail environments is the ‘re-circulating air’, air that has already been breathed in and out by other occupants in the same environment.

Put simply, an air purifier uses a series of filters, such as High Efficiency Particulate Air (HEPA) filters, to capture airborne contaminants, as well as a fan to circulate the air. While this improves IAQ over time, this doesn’t necessarily disinfect the air in the space, it just filters out some pollutants in the air, and then pushes that air back out.

On the other hand, an air steriliser typically uses ionisation, negatively charged ions, and/or UV light to electronically polarise the particles in the air. 

This sanitises and disinfects the air and surfaces in the space, including various viruses and bacteria.

However, Stephen Harkin stresses the importance of being wary of newly emerged companies that claim their air purifier can kill Covid-19, and how their product achieves this.

“There are a lot of ‘pop-up’ air purifier companies suddenly appearing in Ireland and the UK making wild claims. Some of these products on the market are cheaper RRP than it costs us to manufacture our legitimate product. This immediately rings alarm bells.”

Stephen says, “Many of these products have no proper testing or certification, and can often mislead the public by using press releases, case studies, or graphs and pie-charts on a website, or a gimmicky trademark word (®), claiming these are the certifications. These are all just opinions at the end of the day and not official testing or certifications.

“Also be wary of claims such as ‘99.99pc reduction of viruses’. In the small print, it explains this reduction may only occur after several hours, and not on each single air pass. This is ineffective in a live environment. A standard HEPA13 filter would do the same job quicker over this time.”

Stephen adds that often, products can either use ozone as the main source to purify the air, or use plasma/micro-electrostatic plates, which produce ozone as a by-product. Ozone is a highly reactive gas composed of three oxygen atoms.

“Ozone is powerful and brilliant for full sanitisation in the right situation, but it is toxic and detrimental to our health. You should never be around it, as when inhaled, it can cause all sorts of respiratory difficulties. It has no place in our workplaces or our children’s schools.”

According to the Environmental Protection Agency (EPA), several brands have EPA establishment numbers on their packaging, to help identify the specific facility that produces the product.

However, EPA has stated that ‘this number does not imply EPA endorsement or suggest in any way that EPA has found the product to be either safe or effective’. EPA does not certify air-cleaning devices.

“The HSE will not approve any air cleaner technology at the moment, as the sector is not regulated. Anyone can contact the HSE to confirm this.

“Spurious companies may use phrases like ‘medical grade’ or ‘trusted by the HSE’ to get around this, as they may be on the HSE procurement supplier list- this is not endorsement.

“We had tried to get our own products endorsed by the HSE back in November 2020, but to no avail. However, the NHS in the UK have since endorsed all our three products after thoroughly reviewing them, and the TiO² UVC technology. The NHS are releasing their first updated guidelines regarding air quality in 14 years shortly, and we are proud to say our company and products are to be a part of this.”

What to look out for

Stephen says when choosing air sterilisation products, it is important to check and research the following:

  1. Microorganism Deactivation Rate % on each air pass
  2. CADR (Clean Air Delivery Rate) (m³/hr)
  3. CCM (Cumulative Clean Mass) rating
  4. UV-C Wavelength (nm)
  5. UV Irradiation Intensity μW/cm²
  6. Ozone exposure (even as a created by-product)


 “Simply put, UV on its own takes approximately six seconds to deactivate common viruses. Air does not stop and wait for six seconds inside a machine and then begin to move again.”


Stephen’s advice to anyone looking at air sterilisation solutions for their business is to ensure you see results with your own eyes, “Ask for a live demonstration, and ask for the original official certifications. 

“This is an exciting technology and will remain around long after Covid and its variants have gone, for its overall health benefits and additional features.” 

To find out more about our UV-C solutions, visit