Personnel who work in laboratories and directly deal with detecting and examining pathogenic biological agents (PBA) in human biomaterials have to face high risks of becoming infected. At present, working conditions at workplaces of personnel in such laboratories are to be analyzed and checked thoroughly with subsequent implementation of relevant correction measures. We performed qualitative analysis of infection risks in clinical and diagnostic laboratories using a reason tree and event tree analysis and determined a risk probability range for an ending event considering combined effects produced by preconditions. We revealed basic reasons why personnel in medical laboratories became infected when working with PBA. The events were considered at three levels and four directions in their development. We performed mathematical calculation of possible event combinations and determined the whole probability range for occurrence of the events. Quantitative risk analysis showed that a probability of a person becoming infected remained within 0.9∙10–4–0.9∙10–3 range even in case of the most unfavorable outcome. The study provides a well-substantiated conclusion about peculiarities of work tasks accomplished in laboratories; we established that laboratory personnel who were involved in determining drug resistance of microbacteria had the highest risks of infection. The most hazardous scenarios of emergencies were identified; they made the highest contribution to the analyzed risk. We established that a probability of personnel becoming infected that starts with the value being 1.3∙10–6 occurs when immune prevention is neglected and a disease is revealed too late. It is advisable to analyze ways how emergencies develop in medical laboratories since this helps to make necessary amendments in the system and influence factors of its functioning. This analysis procedure gives an opportunity to select the most relevant measures for protection and prevention of emergencies involving PBA leakage out of all the available ones. These measures can reduce risks of infection for personnel down to their acceptable levels.

Personnel who work in laboratories and directly deal with detecting and examining pathogenic biological agents (PBA) in human biomaterials have to face high risks of becoming infected. At present, working conditions at workplaces of personnel in such laboratories are to be analyzed and checked thoroughly with subsequent implementation of relevant correction measures. We performed qualitative analysis of infection risks in clinical and diagnostic laboratories using a reason tree and event tree analysis and determined a risk probability range for an ending event considering combined effects produced by preconditions. We revealed basic reasons why personnel in medical laboratories became infected when working with PBA. The events were considered at three levels and four directions in their development. We performed mathematical calculation of possible event combinations and determined the whole probability range for occurrence of the events. Quantitative risk analysis showed that a probability of a person becoming infected remained within 0.9∙10–4–0.9∙10–3 range even in case of the most unfavorable outcome. The study provides a well-substantiated conclusion about peculiarities of work tasks accomplished in laboratories; we established that laboratory personnel who were involved in determining drug resistance of microbacteria had the highest risks of infection. The most hazardous scenarios of emergencies were identified; they made the highest contribution to the analyzed risk. We established that a probability of personnel becoming infected that starts with the value being 1.3∙10–6 occurs when immune prevention is neglected and a disease is revealed too late. It is advisable to analyze ways how emergencies develop in medical laboratories since this helps to make necessary amendments in the system and influence factors of its functioning. This analysis procedure gives an opportunity to select the most relevant measures for protection and prevention of emergencies involving PBA leakage out of all the available ones. These measures can reduce risks of infection for personnel down to their acceptable levels.