The study shows average particle concentration inside the test office was five times higher during working hours than non-working hours.
And at its highest levels, indoor particle concentration was about three times higher than it was outside.
Morawska said in offices with poor ventilation higher concentrations of particles can "prevail for the whole day."
She says the health risks will be "quite high" for workers that "sit in an office like this for days and months."
Her research team is calling on governments to consider regulating emission levels from laser printers.
But Morawska says more research is needed into the chemical makeup of the emissions and how the particles are released to back any such move.
Her paper includes a list of the brands and models studied and their rating by amount of particles emitted.
A total of 12 models of Hewlett Packard printers and one Toshiba printer are listed as high emitters of tiny particles.
