The 8 dirtiest places in the office (they’re not the ones you’d expect!)

The dirtiest places in the office

Sure, we know the keyboard is crawling with germs and the bathroom door handle is a veritable micro community. But there are a lot of other bacteria hotspots around the office – and many of them are not at all where you’d think.

Here are eight of the dirtiest places in the office.

The copier’s start button

A study by template maker Hloom found that one of the most germ-ridden spots in the office is the photocopier – the start button had over 1.2 billion CFU (colony forming units) per square inch. By comparison, the average school toilet seat has 3,200.

The coffee pot handle

The same study found that the office’s coffee pot handle had over 108 thousand CFU per square inch – 99 per cent of which were gram-negative rods, a type of bacteria that can be resistant to antibiotics. Plus, coffee pot handles appear to be somewhat of a beacon – University of Arizona microbiologist Charles Gerba reportedly put viruses on doorknobs to see how fast they travelled, and found that the first place they popped up was on coffee pot handles.

Coffee pot handle: one of the dirtiest places in the office
Elevator buttons

A few years ago, Sunnybrook hospital swabbed 120 elevator buttons at three hospitals over the course of 10 days – and found that 61 per cent of the swabs showed microbiological growth.

“We were surprised by the frequency of bacterial colonization on the elevator buttons, but we were also struck by how easily it could be avoided,” said one of the study’s co-authors, Andrew Simor, chief of the department of microbiology and infectious diseases at Sunnybrook.

And if a hospital can’t keep its elevators clean, our offices are toast.


Yes, our keyboard and mouse are dirty – this we can just assume. But what about the desk itself? More research by Charles Gerba found that the area by our keyboards that we rest our hands contains up to 10 million instances of bacteria. Interesting fact: Gerba also looked at desk hygiene by profession, and found that the most germ-ridden desks belong to accountants, and the last germy desks belong to lawyers.


A home germ study by NSF International found that 14 per cent of pens tested positive for staphylococcus aureus, or staph. We can’t imagine office writing utensils would fare much better…

The kitchen sink

According to Molly Maid, the dirtiest place in the office is the kitchen faucet. An often-cited study by Kimberly-Clark Professional found that 75 per cent of break room sink faucet handles have an ATP count of 300 or higher. (High levels of Adenosine Triphosphate molecules indicate a surface that is more than likely covered in bacteria. By comparison, a clean surface would have an ATP count of under 25.)

And it’s not just the tap: when wellness blog Well+Good had a microbiologist come to their office to test for germs, the metal drains of the kitchen sink had an ADP count of 1391. “He swears that high number isn’t uncommon for the location,” writes author Katie Maguire (he also said that the kitchen sink is often the dirtiest part of a shared office).

Kitchen sink: one of the dirtiest places in the office
Vending machine buttons

Kimberly-Clark Professional’s study found that 21 per cent of vending machine buttons have an ATP count of 300 or higher – and that info is made all the worse by the fact that workers are usually opening and eating their treat before they even get back to their desk.

Office mugs (and the sponge used to clean them)

The same University of Arizona microbiologist we mentioned before also studied the bacteria on office cups, and found that up to 20 per cent of (clean) office mugs had traces of coliform bacteria (a.k.a. fecal matter) – and once the cups were wiped with a communal dishcloth or sponge, the number jumped up to 100 per cent. After being wiped, 20 per cent of mugs also tested positive for E. coli.

If your office has a dishwasher, this one’s a bit of a moot point – but it’s still important to keep in mind that those washcloths and sponges should be avoided at all costs

Oh, and that microbiologist that visited Well+Good’s office also found a high ATP count on the doors to the cabinet that holds the office cups. Is no place safe?

See also:
6 cool workplace wellness programs
Office design tips for happy, healthy workers


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