Introduction: Chlorine is an aggravating toxic gas with extreme fume. If it were released into the atmosphere during a possible industrial incident, it might cause damages and death. The firm called TKI Hrastnik (Tovarna kemičnih izdelkov Hrastnik) is situated in the municipality of Hrastnik. In the case of uncontrolled release of a large amount of chlorine into the atmosphere, the lives of many people in the town would be endangered. Purpose: The purpose of the presented thesis is to find out if Hrastnik municipality inhabitants are aware of the possible safety measures and first aid in an uncontrolled case of sudden chlorine release into the atmosphere. Methods: The descriptive method and the quantitative research paradigm were used in the process of the research work. Initially, the overview of the professional and scientific Slovene and English literature issued between 2005 and 2018 was done in order to set the research problem. Further on, a questionnaire, including thirteen questions, was prepared for Hrastnik inhabitants in order to get their respond on the awareness of the possible chlorine release into the atmosphere incident. Results: The results of the questionnaire are the following: the questionnaire was answered by 109 people (66 women, 43 men): 32 % of them aged between 61 and 75, 63 % of them have finished some kind of secondary or vocational school, 61 % of them live in the local community called KS Rudnik, the sound of the siren, announcing the chlorine release into the atmosphere incident, would be recognised by 62 % of the people involved in the research, 66.1 % of them are familiar with at least one evacuation place, the presence of the chlorine would be recognized by most of them, only 7 % of the people involved in the research think that chlorine is invisible, 27 % of them think that nausea and vomit are the signs of the chlorine poisoning, 26 % of them would help a poisoned person to leave the contaminated area while 24 % of them would help themselves first and help the others later, 5 % of them would wait for the help of the firemen, 83 % of them would call emergency medical service as soon as they found out the somebody had been contaminated by the chlorine. 46% of them believe their health is medium sized endangered because they live near TKI Hrastnik. Discussion and conclusion: The people involved in the research (who answered the questionnaire) are familiar with the sound signal introducing a direct danger of the chlorine release into the atmosphere. Also, they would notice the presence of chlorine in the air, but they would not be able to offer a suitable first aid to the people involved in the chlorine release incident. It is alarming that Hrastnik inhabitants are not familiar with the position of evacuation places, the meaning of sound signals, the symptoms of possible chlorine poisoning as well as the useful means of protection. Being familiar with all these, people might be able to save the health, even the lives of themselves and the others. Since the people's knowledge of the evacuation meeting places in Hrastnik, the useful means of protection, the sound signals and the symptoms of chlorine poisoning is insufficient, they should be given some extra information on this particular topic.