Introduction:
Microorganisms live in most environments, and one of the most common is air. Bacteria, viruses, and fungi occur as bioaerosols, which allows them to spread. Airborne bacteria are potentially pathogenic, especially in areas densely populated by people.

Aim of the research:
To analyse the microbiological air pollution in different public places – busy streets, a city park, a cinema, and a pharmacy, in Kielce, during autumn and winter.

Material and methods:
The total number of bacteria was estimated based on the sedimentation method. The microbiological condition of air was compared to the standardised Polish norm. Additionally, the macroscopic (bacterial colony) and microscopic (Gram-stained bacterial cells) methods were used for bacterial differentiation.

Results:
Most of the air samples did not exhibit contamination, although the detected cases of significant microbiological pollution do pose a threat to public health. The air on the streets revealed the highest microbial contamination, and the lowest levels of microbes were found in the park. The influence of temperature and population density on the bacterial prevalence in the air has been proven. Despite low air temperatures, the amount of bacteria in most cases was close to the average pollution level. It was also observed that in the pharmacy, the glass separating customers and staff did not reduce the number of bacteria on either side.

Conclusions:
Special attention should be paid to places that can significantly influence the spread of pathogens due to large population (e.g. a cinema) or the presence of sick people (e.g. a pharmacy). Air should be monitored in such places.