The pungent smell that led to the evacuation of Hexagon House on Monday was the result of high levels of hydrogen sulfide (H2S), the Malta Environment and Planning Authority said in a statement.

It confirmed that H2S seeped back into the drainage system of the building in Marsa from the main sewage system of the Drainage Department.

MEPA said that a series of inspections carried out yesterday and today by independent experts from Malta Shipyards and the Drainage Department certified that the levels of H2S, hydrocarbons, thiols (mercaptans) and carbon monoxide within the Hexagon building and the sewage connection located at the main gate were below detection limits at the time of the inspection.

The level of oxygen was also verified as normal. The Occupational Health and Safety Authority has declared itself satisfied with the tests.

MEPA said that as a precautionary measure, over these two days, it carried out engineering works on its drainage system by adding a number of interceptors to its underground galley. It was also looking into purchasing monitoring equipment to check the levels of chemical agents in the air.

In the meantime, it was doing its utmost to ensure that staff were equipped with teleworking facilities to continue carrying on with their duties.

The authority ruled out any possibility of foul play by third parties.

Meanwhile the UHM in a statement, said that contrary to what was claimed by MEPA yesterday, at least one employees was still in hospital this morning as a result of what had happened at Hexagon House.

The union criticised MEPA for having tried to imply that what had happened could have been sabotage.