Bioaerosols play a significant role in indoor air quality (IAQ) as they can be the cause of several health problems, including acute allergies and infectious diseases. This study aimed to characterize and compare the microbial air quality of air-conditioned (AC) and naturally ventilated (NV) office rooms in the Upper Silesia region of Poland. The bacterial samples were collected during the late spring season. Culturable bacteria were deposited on the nutrient media on Petri dishes to investigate the viable-culturable count (VCC) of bacteria and bacterial community structure using a Biolog GEN III system. In total, 12 species of bacteria were identified, with the most isolated Macrococcus equipercicus, Micrococcus luteus D, Staphylococcus xylosus (indoor), and Bacillus species (outdoor). The indoor mean concentrations of bacterial aerosol ranged from 10² to 10³ CFU m⁻³, below Polish proposals for threshold limit standards in office buildings. The indoor-to-outdoor (I/O) ratios indicated that studied air pollutants in the office rooms originated from the indoor air. These results, together with community composition of bacteria, indicate that most of the bacteria present in the studied office building were relatively fresh and of human origin. Multi-antibiotic resistance (MAR) tests showed that the most antibiotic-resistant features were present in Macrococcus species. The office building exposure dose (OBED) and mass median aerodynamic diameter (MMAD) of bacteria aerosol were estimated. The highest value of OBED over the study period was obtained for staff working in offices with natural ventilation (141 CFU kg⁻¹), in contrast to the value for staff working in offices equipped with air conditioning (about 100 CFU kg⁻¹). The MMAD of viable airborne bacteria was higher in AC offices (2.4 μm) than in NV offices (2.2 μm).

Suspended particles with the aerodynamic diameters not greater than 2.5 μm (PM_2.5) and 1 μm (PM₁, sub-fraction of PM_2.5) were sampled at three sites: an urban background site, rural background site, and urban traffic site in southern Poland. In total, there were 240 samples taken within 02.08.2009–27.12.2010. Fifteen polycyclic aromatic hydrocarbons (PAH) were determined in each dust fraction. The averages of the concentration of total PAH (ΣPAH) and of particular PAH, as well as the share of carcinogenic PAH in total PAH (ΣPAH_carc/ΣPAH), carcinogenic equivalent, mutagenic equivalent, and TCDD-toxic equivalent appeared high compared to other areas in the world. Their high values express the significance of health hazard from PM and PM-bound PAH in southern Poland. The diagnostic ratios suggest that PM-bound PAH originate from municipal (PM_1−2.5) and vehicular (PM₁) combustion.

Thirteen fractions of ambient dust were investigated in Zabrze, a typical urban area in the central part of Upper Silesia (Poland), during a heating season. Fifteen PAH and Cr, Mn, Co, Ni, As, Se, Cd, Pb contents of each fraction were determined. The dust was sampled with use of a cascade impactor and chemically analyzed with an energy dispersive X-ray fluorescence spectrometer (PANalytical Epsilon 5) and a gas chromatograph with a flame ionisation detector (Perkin Elmer Clarus 500). The concentrations of PM1 and the PM1-related PAH and elements were much higher than the ones of the coarse dust (PM2.5-10) and the substances contained in it. The concentrations of total PAH and carcinogenic PAH were very high (the concentrations of PM1-, PM2.5-, and PM10-related BaP were 16.08, 19.19, 19.32 ng m-3, respectively). The municipal emission, resulted mainly from hard coal combustion processes, appeared to be the main factor affecting the air quality in Zabrze in winter.