Interserve (Defence) was in charge of maintaining the Arncott base.
Oxford Crown Court heard that an asbestos survey undertaken in the boiler room at the base in 2005 found that the whole room was considered to be contaminated with asbestos and recommended that access to the room should be restricted until it was removed.
Interserve failed to follow the advice of the survey and consequently workers were left at risk of exposure to deadly asbestos fibres for over a year.
The company pleaded guilty at a previous hearing at Banbury Magistrates Court to contravening asbestos regulations.
HSE Inspector for Oxfordshire, Matthew Lee, said: “Around 4,000 people die each year from past exposure to asbestos and the material may be present in any building built before the year 2000.
“It is therefore essential that duty holders and facilities managers are aware of the risk it still poses and their responsibilities in managing it.
“Facilities managers are key to ensuring that effective management systems are in place to protect workers and to ensure that duty holders meet their legal responsibilities.”