A.I. Borodulin

Inactivation of Viruses in Bubbling Processes Utilized for Personal Bioaerosol Monitoring

ABSTRACT A new personal bioaerosol sampler has recently been developed and evaluated for sampling of viable airborne bacteria and fungi under controlled laboratory conditions and in the field. The operational principle of the device is based on the passage of air through porous medium immersed in liquid. This process leads to the formation of bubbles within the filter as the carrier gas passes through and thus provides effective mechanisms for aerosol removal. As demonstrated in previous studies, the culturability of sampled bacterium and fungi remained high for the entire 8-h sampling period. The present study is the first step of the evaluation of the new sampler for monitoring of viable airborne viruses. It focuses on the investigation of the inactivation rate of viruses in the bubbling process during 4 h of continuous operation. Four microbes were used in this study, influenza, measles, mumps, and vaccinia viruses. It was found that the use of distilled water as the collection fluid was associated with a relatively high decay rate. A significant improvement was achieved by utilizing virus maintenance fluid prepared by using Hanks solution with appropriate additives. The survival rates of the influenza, measles, and mumps viruses were increased by 1.4 log, 0.83 log, and 0.82 log, respectively, after the first hour of operation compared to bubbling through the sterile water. The same trend was observed throughout the entire 4-h experiment. There was no significant difference observed only for the robust vaccinia virus.

Monitoring of viable airborne SARS virus in ambient air

Abstract Due to recent SARS related issues (Science 300 (5624) 1394; Nature 423 (2003) 240; Science 300 (5627) 1966), the development of reliable airborne virus monitoring procedures has become galvanized by an exceptional sense of urgency and is presently in a high demand (In: Cox, C.S., Wathers, C.M. (Eds.), Bioaerosols Handbook, Lewis Publishers, Boca Raton, FL, 1995, pp. 247–267). Based on engineering control method (Aerosol Science and Technology 31 (1999) 249; 35 (2001) 852), which was previously applied to the removal of particles from gas carriers, a new personal bioaerosol sampler has been developed. Contaminated air is bubbled through porous medium submerged into liquid and subsequently split into multitude of very small bubbles. The particulates are scavenged by these bubbles, and, thus, effectively removed. The current study explores its feasibility for monitoring of viable airborne SARS virus. It was found that the natural decay of such virus in the collection fluid was around 0.75 and 1.76lg during 2 and 4h of continuous operation, respectively. Theoretical microbial recovery rates of higher than 55 and 19% were calculated for 1 and 2h of operation, respectively. Thus, the new sampling method of direct non-violent collection of viable airborne SARS virus into the appropriate liquid environment was found suitable for monitoring of such stress sensitive virus.

Variability of the content of live microorganisms in the atmospheric aerosol in southern regions of western Siberia.

The results of preliminary studies on the biological component of atmospheric aerosol and annual dynamics of the total atmospheric aerosol protein concentration in the southern regions of Western Siberia were considered in the preceding works [1, 2]. Live microorganisms contained in atmospheric aerosols can be transferred over large distances and to high altitudes without loss of viability [3–7]. Therefore, the properties of the biological component of atmospheric aerosols and sources of their origin should be studied not only near the ground, but also at high altitudes. In this work, we describe the results of measurements of the concentrations of live microorganisms and the compositions of atmospheric aerosols above large forests in the southern regions of Western Siberia.

Measurement Errors in Determining Tropospheric Bioaerosol Concentrations in the Southern Region of Western Siberia

The Research Institute of Aerobiology of the State Research Center of Virology and Biotechnology “Vector” and the Institute of Atmosphere Optics of the Siberian Division, Russian Academy of Sciences have been systematically monitoring tropospheric biogenic aerosols (bioaerosols) in the southern region of Western Siberia since December 1998. Samples of atmospheric air are taken at altitudes of 0.5, 1, 1.5, 2, 3, 4, 5.5, and 7 km using a plane–laboratory Optik-E during one day in the last third of every month to determine the total protein content and the amount of viable microorganisms. The research methods and summarized results of the studies are described in detail elsewhere [1, 2].

Personal sampler for monitoring of viable viruses; modelling of outdoor sampling conditions

Abstract A new personal bioaerosol sampler has recently been developed and verified to be very efficient for monitoring of viable airborne bacteria, fungi and viruses. The device is capable of providing high recovery rates even for microorganisms which are rather sensitive to physical and biological stresses. However, some mathematical procedure is required for realistic calculation of an actual concentration of viable bioaerosols in the air taking into account a rate of inactivation of targeted microorganisms, sampling parameters, and results of microbial analysis of collecting liquid from the sampler. In this paper, we develop such procedure along with the model of aerosol propagation for outdoor conditions. Combining these procedures allows one to determine the optimal sampling locations for the best possible coverage of the area to be monitored. A hypothetical episode concerned with terrorists’ attack during music concert in the central square of Novosibirsk, Russia was considered to evaluate possible coverage of the area by sampling equipment to detect bioaerosols at various locations within the square. It was found that, for chosen bioaerosol generation parameters and weather conditions, the new personal sampler would be capable to reliably detect pathogens at all locations occupied by crowd, even at distances of up to 600m from the source.

Periodic Structure of Surface Fields of the Net Atmospheric Protein Aerosol Concentration in the Outskirts of the City of Novosibirsk

The biogenic component of the atmospheric aerosol in the southern regions of Western Siberia is a subject of systematic monitoring implemented at the Vector State Research Center for Virology and Biotechnology in collaboration with some institutes of the Siberian Division of the Russian Academy of Sciences [1–4]. Net atmospheric protein is the most representative component of the biogenic atmospheric aerosol. The first results of studies on the variation of the protein component of tropospheric aerosol above large forests of the southern regions of Western Siberia were reported in [1]. These data were analyzed in more detail in [4]. In parallel with high-altitude monitoring, we also studied the surface fields of the concentration of the biogenic component of the atmospheric aerosol. The goal of this work was to apply the methods of wavelet and harmonic analysis to the processing of the set of experimental data on the mass concentration of the atmospheric aerosol and the concentration of net protein in the surface layer of the atmosphere measured in the outskirts of the city of Novosibirsk.

Personal Sampler for Monitoring of Viable Viruses; Modeling of Indoor Sampling Conditions

This article describes the development of a mathematical model for evaluation of particle concentration for indoor air conditions. The results of modeling could be used to predict particle concentration in an ambient air at different distances from the source, taking into account space geometry and ventilation/air conditioning created air streams. Two case studies were then undertaken to determine the particle concentration at hypothetical shopping center for the situations when: (1) the ambient air movement is created by a local ventilation system, and (2) besides the local ventilation, the outdoor air enters the space influencing particle distribution situation due to mixing with ventilation created air streams. The results of modeling were used to evaluate the minimal source concentration of virus containing aerosols measurable by our recently developed personal bioaerosol sampler moving along various routes during certain time intervals.

Statistics of the concentration of tropospheric bioaerosol.

Although statistical aspects of the distribution of atmospheric impurity concentration have long been a subject of extensive discussion in the literature, this problem is still of considerable theoretical and applied importance. The biogenic component of tropospheric aerosol in the southern regions of Western Siberia is a subject of systematic research at the Research Institute of Aerobiology, Vector State Research Center for Virology and Biotechnology, in collaboration with the Institute of Atmosphere Optics, Siberian Division, Russian Academy of Sciences [1, 2]. The term “biogenic component” is assumed to include only two fractions of atmospheric aerosol: total protein and live microorganisms. The results of the study and preliminary results of their generalization showed that there is a significant scatter of the value of the biogenic component of tropospheric aerosol within the altitude range from 0.5 to 7 km. This effect cannot be attributed to the measuring error alone. Therefore, it should be explained by the statistical nature of the scatter.