The cause of the illness in the south building at Johns Hopkins at Keswick facility is nitrates in a hot water heater, and both buildings will be open for business, according to a message on the complex’s website.
A hot water heater was reportedly harboring the nitrates that made it into the south building’s hot water service.
"First of all, nitrates and nitrites can cause the types of symptoms that employees reported. Second, the north side of the south building, where running water with those chemicals was found, is served by that hot water heater. Third, that is also the side of the building where sickened employees have reported coming into contact with water in various ways: eating food cooked with hot water, drinking beverages made with hot water, or using restrooms," accroding to the message on the website.
According to the Environmental Protection Agency, nitrates are "nitrogen-oxygen chemical units which combine with various organic and inorganic compounds."
"The major sources of nitrates in drinking water are runoff from fertilizer use; leaking from septic tanks, sewage; and erosion of natural deposits," according to the EPA's website.
On Tuesday, the south building was evacuated after 17 employees reported feeling ill. Eventually that number rose to 23 employees reported feeling ill by Wednesday morning.
Both the north and the south buildings at the complex were closed on Wednesday so the Baltimore City Health Department could look for the cause of the illness.