This article presents basic issues related to effectiveness improvements of adverse events reporting systems and a just culture in the context of ISO 45001:2018 standard - Occupational health and safety management systems implementation. The organizations, that want to implement the new standard, need effective tools to make their reporting systems more effective because of some new requirements of the standard laws. Some proven solution of that have been used for some time past especially in aviation and medicine. It is a confidential, voluntary reporting system as a useful complement to a compulsory reporting system and the just culture. The just culture is described as an atmosphere of trust in which people are encouraged for providing essential safety-related information - but in which they are also clear about where the line must be drawn between acceptable and unacceptable behavior. The tool supports the organizations with handling blame and punishment. In addition, there is information about the factors determining the growth of undesirable occurrence reports number in the organisations and ways to classify the behaviour and attitudes of employees as acceptable or not.