Chlorine emergency

Due to the storage and usage of chlorine, our water treatment plant has been classified as a category B company with a risk of a major accident. Water Treatment Plant at Ülemiste treats surface water to produce drinking water. In this process, chlorine is used on disinfecting purposes. The Republic of Estonia has prepared and provided a chemical data sheet, risk assessment, description of the safety system and a contingency plan to all the competent state authorities. The company holds a valid license no OKK-19-11, issued on 28.11.2011.


Chlorine gas is toxic and suffocating when inhaled, it irritates eyes, skin and respiratory system. Chlorine has a strong oxidising effect and is extremely toxic to aquatic organisms.

Chlorine used at the treatment plant can cause a major accident in case of an extensive chlorine leakage in the chlorine storage. A cloud of chlorine gas spreads downwind of the leaking point. Chlorine gas is greenish yellow, with a pungent odour, heavier than air. When joining the steam in the air, it forms a white fog. Spreading downwind, it settles in lower-lying areas, ditches and underground communications. With raising air flows, it vanishes into atmosphere.


We arrange regular training sessions for our employees. The company does continuous cooperation, exchanges information and organizes training exercises together with the Northern Rescue Centre of the Rescue Board, in order to ensure the necessary preparedness and action in the event of a major accident, and to reduce the consequences of a disaster.


In the event of a major accident, the surrounding population is notified by using alternating siren tones at 60sec/30sec intervals. The sites in the neighbourhood of the water treatment plant are notified by passing the message through the loudspeakers. Also, the rescue services and the media are informed about the emergency. We suggest you turn the radio on to Vikerraadio at the frequency of 104,1 Mhz and watch the news from the national television channel ETV. More information from our website at

How to behave in the event of a chlorine emergency

  • When you hear the siren, leave the danger zone, moving further away by crossing the wind direction. If possible, go inside and stay there. Close the doors and windows, the vents and the ventilation. Inform you neighbours about the danger.
  • Start using a wet towel or some other textile material for breathing when you smell the chlorine. Use the shower in case of a strong chlorine odour, as water will neutralise the chlorine gas.
  • In the event of an emergency, follow all the instructions given by the rescue services (Emergency Act).

How to recognize an intoxication

Chlorine causes damage to tissues, irritates the mucous membranes, causes nonproductive coughing, sneezing, and sometimes also vomiting. Higher concentrations may cause chest pain, tearing and abnormal coordination.

Contacts: Water Treatment Manager: ph 62 62 510; Chief Technologist: ph 62 62 610

Danger zone, according to the risk assessment: