Since the onset of the global Covid-19 pandemic in 2020, organisations of all sizes have been tasked with implementing enhanced deep cleaning and sanitising processes in order to provide a safe environment for any staff, customers, visitors or students who may enter. This enhanced level of sanitation is something organisations may not have been particularly familiar with prior to recent times, so it’s understandable that many people are unaware of the different sterilising options available to them or what the differences are from one method to another.


In an attempt to help organisations understand the options available to them, and to make informed decisions on which option would best suit their needs, we have outlined below the pros and cons of the three main room disinfection options available at this time: fogging disinfection, UV light, and ozone.


Fogging / Misting / Fumigation

Fumigation or fogging disinfection methods work by spraying a mist of vaporised chemical disinfectants, such as hydrogen peroxide. This fog fills a well-sealed room, settling on surfaces and inactivating any microorganisms that may be residing there. Fogging disinfection is primarily offered as a service, however there do exist some devices that can be purchased so that organisations can take fumigation into their own hands.



  • Fog can settle into nooks and crannies that may not be well-exposed.
  • Medium-term effectiveness – some fogging disinfection services can provide lasting results for up to 28 days of sanitation from a single application.



  • Health impacts – the World Health Organisation has advised against the use of fumigation disinfection methods as these can have negative impacts on eyes and respiratory systems of workers in environments where fogging is implemented.
  • Residual chemicals are left on surfaces after disinfection, which can be harmful to the environment and to peoples’ health with long-term usage.
  • Disruption – fogging requires the premises to be emptied of people for the duration of the process, and people may not enter the premises for a length of time after completion.
  • Cost – it is recommended that fogging disinfection be completed once per month to maintain high levels of sanitation. This can be costly if employing external service providers for such regular decontaminations.


UV Sterilising

Uses short-wavelength ultraviolet (UV) light to kill or inactivate microorganisms. Direct exposure to UV-C radiation destroys the outer skin (the protein coating) of all viruses, bacteria, fungi and mould, which makes them unable to reproduce or to be transmitted any further. UV sterilising devices shine powerful beams of UV-C light in their surroundings, effectively disabling any organisms the light comes into contact with. UV-C has been used for many years to sterilise hospital settings.



  • Chemical free – no chemicals are used, therefore there are no chemical residues left after use.
  • Sterilises air, surfaces and liquids.
  • Quick and efficient – although disinfection rates will vary depending on room size, an average sized room can be sterilised in a matter of minutes, and the room is immediately usable once the process has finished.
  • Hands-free – users simply need to turn on the device.
  • Control – UV sterilisers are generally sold or leased, rather than offered as a service. This gives the organisation control over when and where they sanitise their premises.
  • Long-term investment – although these devices can be costly upfront, they provide the ability to sterilise premises as and when needed for a number of years. This allows for consistent sterilisation against viruses and bacteria into the future, protecting staff, customers and visitors, and minimising the spread of illnesses onsite.


  • Sterilizes only air / surfaces that come into contact with the light – any areas shaded or underneath other items may not be sanitised.
  • UV-C is harmful to humans, plants and pets – for UV devices offering full room sterilising, users must leave the room for the duration of the process. Other products do exist, however, such as upper room sterilisers, which focus their UV beams upwards towards the ceiling. Upper room sterilisers can be used with people in the room, though these will sterilise only the air circulating in the room as surfaces will be untouched by UV light.
  • Variable levels of effectiveness – different UV-C products exist offering sterilising properties, however not all devices offer the same strength of decontamination. For effective sterilising against SARS-Cov-2 (Covid-19), a 6-log kill dose of UV-C is required. It’s important that users consider device specifications before purchasing or renting a UV-C room steriliser to ensure it’s fit for purpose.



Ozone (O3) is a gas made up of three oxygen molecules. Similar to UV, Ozone works by destroying the outer shell of microorganism DNA, rendering them unable to reproduce. It has been used for many years as a treatment for drinking water. Ozone can be used to sterilise premises either by employing an external service provider or by purchasing an ozone sterilising device – however extreme caution must be taken by any person using ozone so training is required.



  • Ozone can be sprayed through air vents & ducts for air flow sanitising.
  • Gas can settle into nooks and crannies that may not be well-exposed.
  • Removes bad smells.


  • Ozone is toxic to humans and animals, and can be harmful to health. Inhalation of relatively low amounts of ozone can cause chest pain, coughing, shortness of breath and throat irritation. Ozone may also worsen respiratory diseases such as asthma, and reduce the body’s ability to fight respiratory infections.
  • Ozone is highly unstable, with a half-life of approximately 22 minutes at room temperature.
  • Like fogging, it’s important to allow time for the gas to dissipate after disinfection has completed, so people must avoid entering for a period of time after sterilising.


It’s clear that there are strengths and downfalls to each sanitising method available, so it’s important that any health and safety officers or other decision makers take the time to carefully review all available options to determine which suits the needs of your organisation best. For some organisations, using chemical-free solutions such as UV may be favourable – particularly if there are people who will be entering your premises on a regular basis and may want to minimise chemical exposure / inhalation. For others, spraying a vapour to fill nooks and crannies may be favourable if your organisation is heavily cluttered or shadowed.



If UV sterilising is something your organisation would like to consider, CW Applied Technology offers the Muv-X portable room steriliser. This device can be wheeled from room to room, and produces the 6-log kill dose of UV-C radiation required to inactivate SARS-Cov-2 (Covid-19) to 99.9999% effectiveness. For more information on this device, or to book a free, no-obligation Zoom demonstration, please see