According to WHO definition, indoor air quality is an important determinant of human health. Emissions from building materials, furniture, and consumer goods, combustion processes, and infiltration of polluted atmospheric air are considered the main sources of hazardous chemicals and solid pollutants in indoor air. Aim. To conduct an analysis of the results of comprehensive sanitary and hygienic studies of air quality in residential buildings and apartments in order to determine priority chemical pollutants and products of their transformation; justify the need to improve the air quality monitoring system of residential premises taking into account modern WHO recommendations. Materials and Methods. The study of air samples of residential premises was carried out on the basis of the L.I. Medved’s Research Center of Preventive Toxicology, Food and Chemical Safety of the Ministry of Health of Ukraine (2000-2015) and Kyiv Center for Disease Control and Prevention of the Ministry of Health of Ukraine (2015-2019). A comprehensive toxicological and hygienic assessment of the air in residential premises was carried out based on the appeals of citizens who complained about the unpleasant smell of the air. A total of 123 residential objects (856 samples) were investigated. Applied methods of systematic and comparative analysis, cross-sectional survey method (survey of residents of residential buildings and apartments), sanitary and hygienic methods; sanitary and chemical methods (29 methods according to the institution's accreditation). Statistical data processing was performed using the IBM SPSS Statistics 29.0.0.0 program (Spearman correlation analysis), with p≤0.05. Results. A high level of chemical air pollution in residential premises, carried out based on citizen complaints, was established. Various external and internal sources of chemical air pollution were determined, in particular by marker pollutants: formaldehyde, phenol, and acetone. It has been established that the cause of their emission into the air is household items (furniture), various construction and finishing materials (polymers), which are used mainly during repair work or in new buildings. A direct positive connection was found between the level of exceeding the maximum permissible limit of marker chemical pollutants and the well-being and health of residents of settlements. Symptoms such as fatigue, cough, diseases of the upper respiratory tract, headaches and dizziness, allergic conditions were most often observed, which determines the urgency of improving the preventive work of primary care doctors ‒ family medicine in the direction of detecting pre-pathological conditions among healthy individuals and especially sensitive contingents (children, teenagers, pregnant women) living in the conditions of a "sick building". Conclusions. The unsatisfactory state of air inside residential premises determines the need to improve the existing system of monitoring the quality of air inside residential premises, in particular, improving methods of sampling and analysis of priority chemical indoor air pollutants to assess the risk of their combined action. Keywords: indoor air, "sick building syndrome", phenol, formaldehyde.