OTTAWA -- OC Transpo has implemented a mandatory face mask policy in all employee common areas following a series of cases of COVID-19 at the transit service.

Seven OC Transpo drivers have tested positive for COVID-19 since Aug. 9. Four employees that don't have contact with the public have also tested positive over the past two weeks.

In a statement to CTV News Ottawa, Director of Transit Operations Troy Charter says OC Transpo has recently implemented additional measures to continue to make its work environment as "safe as possible for our employees."

"This includes making masks mandatory in all common areas, such as break rooms, reporting facilities and lunchrooms, providing additional hand sanitizers outside building entrances and ongoing monitoring.

Charter says OC Transpo works with Ottawa Public Health on every case of an employee testing positive for COVID-19.

"Of the almost 3,000 employees at OC Transpo, 28 employees have tested positive for COVID-19 as of 5 p.m. Aug. 21," writes Charter in a weekend email to CTV News Ottawa.

"Not all of these employees had contact with the public."

Charter says OC Transpo will continue to make adjustments as the COVID-19 situation evolves and implement additional measures to "stay abreast of industry trends and in close consultation with OPH."