Germs All Around Us

Germs All Around Us

A study released by “The Healthy Workplace Project”, sponsored by Kimberly-Clark, showed that the dirtiest place in an office is not the bathroom, but is in fact the office kitchen or break area. This study, led by a professor of microbiology at the University of Arizona, tested for levels of microbiological contamination by swabbing 4,800 surfaces in office buildings that had more than 3,000 employees. To quickly assess the level of contamination on these surfaces, the researchers measured the levels of Adenosine Triphosphate (ATP), a substance present in every cell and acts as an energy source for metabolism within the cells. It is worth noting at this point that testing for ATP on surfaces will pick up the presence of any cell: animal, vegetable, bacterial, yeast and mould cells, most of which are completely benign. So the presence of ATP is indicative of poor cleaning and residual soiling, rather than a strict hygiene hazard.

The study broadly found that high-touch surfaces were the most contaminated. Surfaces tested as part of the study that produced the highest ATP figure (300 or higher) were [1]:

  1. 75% Sink Taps (faucets)
  2. 48% Microwave door handles
  3. 27% Keyboards
  4. 26% Refrigerator door handles
  5. 23% Water fountain buttons
  6. 21% Vending machine buttons

As you can imagine, and expect, these areas are very frequently touched or handled in the same place by many different people. So, everytime someone touches one of these areas they are leaving behind some of their own cells, skin oils, sweat and other contaminants, but they are also pickup other contaminants left behind by other people. This method of transfer is a very common method for bacteria and viruses, like the norovirus to spread from one person to another: think how often someone touches their face during the day, how often you touch food with your hands after coming from the kitchen. So it is hardly suprising that contamination spreads out to include the keyboard.

One thing to bear in mind is that we come in contact with “germs” everyday and our body ceaselessly combats the threat. In fact we need contact with these threats in order to build a strong immune system. Not all “germs” are bad for us, it has been estimated that on average we have around 500-1000 different bacteria in our body and most of them serve an important function in the body.

In conclusion, this study highlights the simple fact that cleaning is not effectively done on the surfaces reporting a high ATP. However, this could be because cleaning isn’t done during the day and that the contamination builds up very quickly. While Kimberly-Clark obviously have an interest in sponsoring this study, they do sell disinfection product, they have drawn attention to areas and surfaces that need to be cleaned carefully and, if required, disinfected.

One further point which was not part of the study is that disinfection must only be done on a clean surface; the presence of contamination can affect the kill potential of certain disinfectant types.


Recent articles in places like “The Cleanlink” have asked how often high-touch surfaces should be disinfected and what kind of disinfectants should be used. It’s worth noting that different working environments obviously different infection control requirements, commercial offices compared to hospital wards are clearly poles apart. But the common theme in this article and others is the choice disinfectant and its efficacy, while that is very important, it cannot be overstated how the process of disinfection is just one part of an overall cleaning system. If the cleaning of high-touch areas is inadequate then the effect of disinfection of that surface could be compromised, and in high-risk areas where the battle with antibiotic-resistant pathogens is relentless, the disinfectant must be allowed to work without interference.

The cleaning and disinfection processes for those high-touch areas, including the surrounding areas, needs to be approached as a system, not just which cleaning product or disinfectant to use or when to clean.


Rafael Cobos