Smiling cartoon businesswoman is laundering illegal obtained dirty money in plastic basin and hanging up on clothesline

One of the most common questions facility managers have when they discover harmful pathogens are present in their facilities is, how did it get there?

"We can't always tell how pathogens end up on a surface, but what we do know, is that they can be found just about anywhere", according to Brad Evans, general manager at OptiSolve, a company offering surface imaging technologies to help locate microbial contamination on surfaces so it can be removed.

A study conducted last year in Hong Kong might offer some potential answers.

Researchers at the University of Hong Kong wanted to know if the paper money used in the city was contaminated and if so, if those contaminants could be passed on to people's hands, on to surfaces, and then transferred to other people.

They collected 15 paper bills from cashiers at 12 hospitals across the city. With each bill, they lightly scraped the surface and cultured the scrapings in a petri dish. The test results confirmed that there were bacteria on the bills and that it was growing steadily.

Among the bacteria found on the bills were Propionibacterium acnes, which are linked to skin acne, but can also cause sarcoidosis, an inflammatory disease.

Furthermore, a bacterium called Acinetobacter was also present. These can cause human infections such as pneumonia and usually impact people with weak immune systems.

What the researchers found next helps answer the question as to how pathogens can make their way onto surfaces outside the hospital.

The same bacteria found on the hospital bills was soon found in the city's metro stations serving the 12 hospitals. It was even found on the palms of randomly selected people in the metro stations as well as the air in the stations.

"This gives you an idea of how pathogens can spread both within and outside a facility," says Evans. "The researchers concluded that when pathogens are found on common high-touch surfaces such as doorknobs, it serves as an 'alert' that more pathogens are present and are likely to be present on many other surfaces."