The general population spends almost 90 percent of their day indoors, most of it working in an office. That said, a recent study found that these areas harbor a variety of bacteria.

Joint research between San Diego State University and the University of Arizona tested 90 offices in three cities and found more than 500 species of bacteria, about the same number found in previous studies of bathrooms and aircraft. Researchers swabbed five surfaces — chairs, phones, computer mouses, keyboards and desktops, and discovered that the highest concentrations of microbes were on chairs and phones.

The study found that humans were the main source of bacterial abundance in offices, with skin, oral and nasal cavities harboring trillions of micro-organisms that can shed and accumulate in work spaces.

But not all bacteria are created equal as some of them are hardier than others. Professor Peter Collignon, infectious diseases specialist at the Australian National University, said that certain microbes die off quickly while those that can reproduce can hang around for years.

"You would expect most bacteria on surfaces to die off within hours to days but there will be exceptions to that. Some bacteria have spores which are a bit like seeds. They can keep reproducing for many months if not years," he said.

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