In addition to the accumulation of carbon monoxide to potentially hazardous levels -- due to aging exhaust fans that no longer work the way they're supposed to -- there is also concern a fire could break out in the tunnel, The Washington Post reported Friday.

The Wawona Tunnel is identified in a report by the Interior Department's inspector general as one of dozens of safety hazards that Interior needs to repair, The Post said.

The report found problems at work sites, schools, dams and four national parks run by the department.

Auditors said they uncovered a pattern of department managers delaying repairs for long-standing safety problems that threatened the public as well as their own employees, the report said.

Inspector General Earl Devaney said the Interior Department "must take immediate steps to prevent existing hazards from escalating into deadly ones."