Why your doorknob and bell are likely spots for harbouring germs
Coughs and sneezes undoubtedly spread diseases, but when it comes to coronavirus, doorknobs, chair arms and handrails may pose a bigger risk of infection.
Surface contamination has been found to be more significant than first thought with some infectious agents surviving in hospitals for 46 months.
Couple that with the fact that we touch our faces an average of 23 times a day while awake, and suddenly the risk of inadvertently transferring a bacterium or virus through the mouth, eyes or nose is stark. Prof Chris Whitty, the Government’s chief medical officer, has warned that there will be “some risk of transmission” from touching hand rails and hard surfaces for up to 72 hours.
“Just touching it will not give you the virus. It is if you touch it and then touch your face, having not washed your hands between them,” he said. “So, if you go on to the Tube and touch the rail, that’s fine, but just be aware of what you do with your hands – don’t touch your face, wash your hands, and then you can do what you like.”
Other studies suggest viruses can hang around for longer depending on the surface. A recent analysis by the University Medicine Greifswald in Germany, found SARS can cling to plastic for up to nine days.
Veterinary coronaviruses have been shown to persist even longer, for 28 days, and it is unknown how long the new virus will last outside of the body.
Human coronaviruses have been found to live on metal, paper, PVC, ceramics and Teflon for five days, and wood and glass for four.
Viruses causing respiratory infections are spread by droplets expelled by coughs and sneezes, which can contaminate the environment at distances of 6.5ft (2m) and 19.6ft (6m) respectively, and just one single droplet can be enough to carry an infectious dose
The University of Southampton has also shown that respiratory viruses are particularly good at lingering on surfaces for multiple days.
Prof William Keevil, an environmental healthcare expert at Southampton, said: “Our coronavirus work showed these viruses can survive 3-4 days on common touch surfaces such as plastics, ceramics, glass and stainless steel – so-called inanimate ‘fomites’ such as door handles, chair arms, worktops, stair rails etc – making hand transmission to eyes, nose and mouth a potential risk. Therefore, wash hands regularly, clean work surfaces and try to avoid touching the eyes, nose and mouth.”
Prof Günter Kampf from the
Greifswald University Hospital, said infections were often passed on in hospitals through the touching of call buttons, which are often made of metal or plastic. Outside of hospitals, communal objects such as door knobs, telephones, worktops, keyboards, doorbells and even chip-and-pin devices could all be sources of infection, with low temperature and high air humidity further increasing their lifespan.
In 2018, a study by the National Institute for Health and Welfare in Finland found that half of airport security trays tested had traces of cold and flu viruses.
Studies on influenza have found that touching an object for just five seconds can transfer 31.6 per cent of the viral load on to the hands.
Dr Tom Wingfield, a senior clinical lecturer and honorary consultant physician at the Liverpool School of Tropical Medicine, said people should carry out “careful cleaning” of frequently used, shared or touched surfaces such as handles and desks.
The World Health Organisation recommends “ensuring that environmental cleaning and disinfection procedures are followed consistently and correctly. Thoroughly cleaning environmental surfaces with water and detergent and applying commonly used hospital-level disinfectants (such as sodium hypochlorite) are effective and sufficient procedures.”
The recent German study found a solution of at least 1 per cent bleach reduced the infectiousness of surfaces.
“Different coronaviruses were analysed, and the results were all similar,” said Dr Eike Steinmann, of Ruhr University Bochum.