A B S T R A C T Atmospheric aerosol particles of biological origin are a very diverse group of biological materials and structures, including microorganisms, dispersal units, fragments and excretions of biological organisms. In recent years, the impact of biological aerosol particles on atmospheric processes has been studied with increasing intensity, and a wealth of new information and insights has been gained. This review outlines the current knowledge on major categories of primary biological aerosol particles (PBAP): bacteria and archaea, fungal spores and fragments, pollen, viruses, algae and cyanobacteria, biological crusts and lichens and others like plant or animal fragments and detritus. We give an overview of sampling methods and physical, chemical and biological techniques for PBAP analysis (cultivation, microscopy, DNA/RNA analysis, chemical tracers, optical and mass spectrometry, etc.). Moreover, we address and summarise the current understanding and open questions concerning the influence of PBAP on the atmosphere and climate, i.e. their optical properties and their ability to act as ice nuclei (IN) or cloud condensation nuclei (CCN). We suggest that the following research activities should be pursued in future studies of atmospheric biological aerosol particles: (1) develop efficient and reliable analytical techniques for the identification and quantification of PBAP; (2) apply advanced and standardised techniques to determine the abundance and diversity of PBAP and their seasonal variation at regional and global scales (atmospheric biogeography); (3) determine the emission rates, optical properties, IN and CCN activity of PBAP in field measurements and laboratory experiments; (4) use field and laboratory data to constrain numerical models of atmospheric transport, transformation and climate effects of PBAP.

Air disinfection from bacteria and viruses by means of photocatalytic oxidation is investigated with microorganisms loaded over photocatalysts' films from aerosols. Deposition method and equipment have been developed to load Mycobacterium smegmatis , Bacillus thuringiensis , vaccinia virus, and influenza A (H3N2) virus on slides with undoped TiO(2) and platinized sulfated TiO(2) (Pt/TiO(2)). Inactivation dynamics was measured under UVA irradiation and in the dark. About 90% inactivation is reached in 30 min irradiation on TiO(2) and from 90 to 99.8% on Pt/TiO(2). The first-order inactivation rate coefficient ranged from 0.18 to 0.03 min(-1), over Pt/TiO(2) being higher than on TiO(2) for all microorganisms except Bacillus thuringiensis. The photocatalytic mineralization of Bacillus thuringiensis was performed on TiO(2) and Pt/TiO(2) with different photocatalyst and microorganism loadings. Completeness of mineralization depended on the TiO(2) to bacteria mass ratio. The rate of the photocatalytic carbon dioxide production grows with both the cell mass increase and the photocatalyst mass increase. Pt/TiO(2) showed increased rate of mineralization as well as of the inactivation likely due to a better charge carrier separation in the doped semiconductor photocatalyst. The results demonstrate that photocatalytic filters with deposited TiO(2) or Pt/TiO(2) are able to inactivate aerosol microorganisms and completely decompose them into inorganic products and Pt/TiO(2) provides higher disinfection and mineralization rates.

Multi-year monitoring of atmospheric bioaerosol in Southwestern Siberia revealed the presence of a large number of various culturable microorganisms. It is known that viable microorganisms can cause directly or provoke different human diseases. It's very difficult to evaluate the danger represented by each microorganism to man directly. Therefore, a relatively simple method is required for evaluation of potential danger represented to man by the whole assembly of culturable microorganisms in an atmospheric aerosol sample. For bacteria, the method can be based on a number of individual characteristics of each microorganism determined in the course of biochemical and other test required for identification of the detected bacterium, and a number of other tests. It is proposed to classify the measured individual characteristics of bacteria under four groups of indices responsible for: (i) potential pathogenicity for man; (ii) the numbers of bacteria in the sample; (iii) resistance to unfavorable environmental factors; (iv) drug resistance of bacteria. Each of four groups of indices is numerically evaluated by a certain integral index, which quantitatively reflects the contribution of experimentally determined characteristics of bacteria. Expert evaluation of the contribution of each characteristic of microorganisms to the corresponding group of indices is performed. The generalized index of potential danger of culturable bacteria in atmospheric aerosols for human health is presented as the product of four integral indices summarizing the normalized individual integral indices for all bacteria detected in the sample. The work presents the results of measuring the variations of all the above indices for atmospheric air samples collected during one year.

Background: Biological components of atmospheric aerosol affect the quality of atmospheric air. Long-term trends in changes of the concentrations of total protein (a universal marker of the biogenic component of atmospheric aerosol) and culturable microorganisms in the air are studied. Methods: Atmospheric air samples are taken at two locations in the south of Western Siberia and during airborne sounding of the atmosphere. Sample analysis is carried out in the laboratory using standard culture methods (culturable microorganisms) and the fluorescence method (total protein). Results: Negative trends in the average annual concentration of total protein and culturable microorganisms in the air are revealed over more than 20 years of observations. For the concentration of total protein and culturable microorganisms in the air, intra-annual dynamics is revealed. The ratio of the maximum and minimum values of these concentrations reaches an order of magnitude. The variability of concentrations does not exceed, as a rule, two times for total protein and three times for culturable microorganisms. At the same time, for the data obtained in the course of airborne sounding of the atmosphere, a high temporal stability of the vertical profiles of the studied concentrations was found. The detected biodiversity of culturable microorganisms in atmospheric air samples demonstrates a very high variability at all observation sites. Conclusions: The revealed long-term changes in the biological components of atmospheric aerosol result in a decrease in their contribution to the atmospheric air quality index.