24 Feb Environmental Decontamination of Coronavirus, SARS and other respiratory infections
The coronavirus (2019-nCoV) that we read in the media belongs to a large family of viruses that causes a wide range of respiratory diseases, everything from the common cold to severe acute respiratory syndrome (SARS). SARS, if you can remember created a media storm in 2003 when the first case in China was reported on 2002, resulting in a declared epidemic of more than 8000 cases one year later. SARS was a big news item back then but since then it has fallen off the radar, until a new closely related virus came on the scene in the late 2019. These viruses are very closely related: both appear to have been transmitted from animals to humans (zoonotic) and both cause fever, coughs and breathing difficulties, even respiratory distress in severe cases. People who are more susceptible especially in elderly and immunosuppressed patients could develop pneumonia, kidney failure and even death.
The mode of transmission for the new coronavirus and the family of viruses are predominantly direct person to person contact in droplets expelled through coughing and sneezing. The virus in an infected person takes time to replicate inside the body before being excreted and expelled from the body, which appears in the second week off illness. Other means of transmission include touching objects and items with unwashed contaminated hands, typical after coughing, touching nose and mouth or after using the toilet.
From and cleaning and decontamination perspective, there are a number of points to cover which gives us insight into the nature of the problem: survivability, spread and dispersion and biocide. Outside of a healthcare environment, surfaces in residential or commercial buildings, are by in large, not designed to disinfected, nor are they designed to cleaned thoroughly. Equally, these surfaces and the environment they are in have a significant impact on the survivability of viruses outside of the body. This is an important point to understand, that even though the source (an infected person) has left the area, the viral particles could still be viable for days afterwards. But also, these surfaces are not designed to withstand some corrosive biocides like sodium hypochlorite (bleach).
Normally viruses survive a few hours outside of the body. The Coronavirus has been shown to remain infectious up to 9 days, depending upon the surface material, temperature and humidity. With humidity of 50% or more or temperatures of 30oC or more the virus persists for days. The virus can survive for 2 days on steel surfaces or other nonporous surfaces, but potentially longer on porous surfaces where the virus can penetrate fibres and gaps.
Spread and Dispersion
The next point to cover is how the viral particles spread around a room or area and from person to person. As you go through this step and visualise the spread, you’ll notice patterns linked to human behaviour. If an infected person enters a room, he or she will touch and handle (interact with) a number of different surfaces, it could be a door, door handle, hand rail, chair or table. This person could have a bout of coughing or sneezing, and with now contaminated hands, touch these surfaces. Have a think about all the common surfaces that a person could touch. Now, imagine healthy people in the same room and assuming that they are not breathing in the droplets from the infected person, those healthy people are touching and handling those same surfaces.
These common surfaces where infected and healthy (in fact everyone) interact with are called Hi-touch surfaces. These can be visualised as hot spots in a room or particular surfaces areas of high probability of contamination.
Now, broaden and expand those hi-touch surfaces to include potential surfaces that could have been contaminated by droplets from coughing or sneezing. For example, the edges of tables are hi-touch surfaces, but with respiratory infections the act of sneezing can disperse droplets into the air which then settle on horizontal surfaces like tables.
The third point to cover is the use of a biocide. You must have a biocide in order to provide disinfection but opting for any biocide is wholly inadequate. The biocide used must be specifically designed to be viruicidal – the majority of ‘common off the shelf’ disinfectants are designed to kill bacteria only, not viruses. These common types will have no effect on the coronavirus.
In order to tell the difference, look for disinfectants that are independently tested and marked with BS EN 14476:2013. If the product container, label or information sheet is not marked with this standard – avoid!
- Decontamination starts with the biocide. Make sure that it is certified as a viruicidal and follow all the usage recommendations, particularly the recommended contact time.
- When cleaning and disinfecting always pay very close attention to detail on all hi-touch surfaces and horizontal surfaces
- With viruses like these that are transmitted in droplets carried in the air, pay very close attention to ventilation and A/C systems. Filters and covers could collect viral particles.
- Fabrics and porous surfaces can act to protect virial particles from routine cleaning. These will need to be deep cleaned and disinfected. It follows that the biocide chosen should not damage the materials.
- Isolate and seal room off to all people
- Wear full disposable PPE. Face masks are only needed if there is a risk of droplets or contaminated dust being dispersed into the air
- Work methodically from the highest point in the room to the lowest, and then from the furthest point to the exit.
- Thoroughly clean and disinfect all equipment after use and perform thorough hand hygiene