“Schlauer i d’Wuche” – How do I properly clean the screen of cell phones and the like? – Cash desk espresso

A listener to the SRF consumer magazine “Espresso” is unsettled: she regularly cleans the screen of her smartphone with a disinfectant spray and lens cleaning cloths. Now she reads that the former is not a good idea and she wants to know what applies.

«Espresso» has at Reto Widmer from the SRF digital editorial team, Matthew Nagel by the Federal Materials Testing and Research Institute (Empa) and Adrian Egli requested by the Institute for Medical Microbiology at the University of Zurich.

The most important findings:

• For all types of screens (smartphone, tablet, notebook, monitor) and keyboards, you are on the safe side with a soft, damp cloth (e.g. household or glasses cleaning cloth). To remove coarser dirt or smudges, you could also moisten the cloth with a little soapy water.
• You really have to be careful with disinfectants and other cleaning liquids, especially on the softer surfaces of notebook screens or most keyboards. “With these liquids, you can never say exactly how many aggressive components, alcohol components or solvents are in them,” says materials researcher Matthias Nagel. And SRF digital expert Reto Widmer warns of permanent spots and streaks. Therefore: Test disinfectants and cleaning agents – even if it is noted that they are suitable for screens – in any case beforehand at the very edge of the screen or in one place or rather do without them altogether.

We have around 30,000 bacteria per square centimeter on our skin.

• Caution is also required with keyboards: In principle, it is sufficient to wipe them with a damp cloth and, if necessary, tap them carefully. The gaps can also be sucked out with a vacuum cleaner (reduce suction power!). Cleaning liquids could contribute to the lettering coming off, for example.
• The above-mentioned agents are also well suited in everyday use to wipe away the bacteria that cavort on these surfaces, explains microbiologist Adrian Egli. Normally, they are harmless bacteria such as the so-called staphylococci or streptococci: “These bacteria usually come from our own skin,” says Egli. Depending on the study, their number varies between ten and 4,000 bacteria per square centimeter. For comparison: “We have around 30,000 bacteria per square centimeter on our skin.”

And it is clear that there are always unappetizing or health-problematic specimens among them. Regular cleaning is therefore worthwhile, for example if you have checked your e-mail in the toilet and then go to cook. In a sensitive environment, such as a hospital, everyday methods would not be sufficient, effective disinfectants would be needed there. In a hospital, however, the devices and, for example, the keyboards are usually particularly resistant in this regard.