BALTIMORE (WJZ) –  Health officials say a hot water heater is to blame for sickening workers at an office complex last Tuesday and again on Monday.

Initial testing found a hot water heater in the south building of the complex was identified as a source of nitrates and nitrites, which can cause the symptoms reported by employees in the building. Those symptoms include dizziness, nausea, difficulty breathing and vomiting.

The hot water heater in question was isolated from the system last Wednesday and has since been replaced.

Health officials also say the Johns Hopkins at Keswick administrative complex can reopen Wednesday under the following conditions:

•  All water to the north section of the south building will be turned off during the workday, and access to all water sources in that part of the building will remain blocked. After the workday ends, building management will continue to flush the water systems.
•  Once building management in cooperation with health sanitation inspectors have completed flushing and retesting the system, city and state sanitation officers will recertify the water system for potability and conduct an inspection of the cafeteria.

The Baltimore City Health Department, Maryland Department of Health and Mental Hygiene and Hopkins are continuing to examine the cause of and potential connection to additional illness reported Monday afternoon by 11 Keswick employees.