A Monitor for Airborne Bacteria

A unique agar drum sampler is described which indicates, continuously, the number of viable, bacterial particles per unit volume of air at the time and point of sampling. By selection of the timer and the sampling rate the sampler is suitable for quite a wide range of concentration and time. An impaction line of 484 in. greatly increases the capacity of this device over slit samplers and other instruments designed to give time-concentration data for viable airborne particles. This sampler should prove useful for: (i) monitoring airborne bacteria in hospitals, public places, and food and industrial plants; (ii) decay rate studies of bacterial aerosols; (iii) evaluation of aerial germicides; (iv) determination of effectiveness of air conditioning systems in removing airborne bacteria; and (v) many other studies in aerobiology.     

A personal sampler to monitor airborne particles of biological origin

Aerobiological studies are important in many fields, specifically in medicine as they enable the identification of those airborne particles of biological origin coming into contact with man. These data are useful to evaluate the cause-effect ratio, to prevent allergy, to adjust the dose of drugs. A personal sampler for aerobiological particles (PARTRAP FA 52) was handed over to eleven atopic patients for a monitoring day. The sampling room was placed at about 15 cm from nose and mouth. The patients also underwent the Prick test and RAST test. The personal sampler for aerobiological particles enables a qualitative and quantitative sampling of the air close to the patient. More allergenic particles were found with the aerobiological personal sampling as compared to the sensitisation shown by Prick test and RAST in the same patient. This sampling method can be useful to demonstrate the cause-effect ratio directly near the patient and, moreover and can be indicative for further clinical and immunological investigations.     

Comparison of bacterial recovery by Reuter centrifugal air sampler and slit-to-agar sampler.

Bacterial recovery by a portable Reuter centrifugal air sampler and a standard Mattson-Garvin slit-to-agar air sampler was compared in a series of experiments. Microbial air quality was monitored in seven typical laboratory locations. Tests showed that the Reuter centrifugal air sampler yielded significantly higher recoveries than did the slit-to-agar unit.     

Improved Large-Volume Sampler for the Collection of Bacterial Cells from Aerosol

A modified large-volume sampler was demonstrated to be an efficient device for the collection of mono-disperse aerosols of rhodamine B and poly-disperse aerosols of bacterial cells. Absolute efficiency for collection of rhodamine B varied from 100% with 5-μm particles to about 70% with 0.5-μm particles. The sampler concentrated the particles from 950 liters of air into a flow of between 1 and 2 ml of collecting fluid per min. Spores of Bacillus subtilis var. niger were collected at an efficiency of about 82% compared to the collection in the standard AGI-30 sampler. In the most desirable collecting fluids tested, aerosolized cells of Serratia marcescens, Escherichia coli, and Aerobacter aerogenes were collected at comparative efficiencies of approximately 90, 80, and 90%, respectively. The modified sampler has practical application in the study of aerosol transmission of respiratory pathogens.     

Comparison of Andersen eight-stage and two-stage viable air samplers.

The two-stage, disposable Andersen air sampler gave lower values for aerial concentration of bacterial colony-forming particles than did the eight-stage Andersen viable air sampler in either a swine house or a classroom.     

Mobile slit sampler for pollen and spore sampling on motorways

Summary Pollen allergic patients often develop severe symptoms during or after driving on English motorways, suggesting very high counts due to turbulence from vehicles disturbing the wayside grass which is usually allowed to pollenate. To investigate this hypothesis the author made a slit sampler which is mounted on the vehicle, and indicates directly in litres the amount of air sampled on to a vaseline coated slide. Grass pollen counts as high as 10,000/m³ have been found at the seasonal peak, and high concentrations of spores and pollution from particles of carbon from vehicle exhausts have been observed. The device can take serial samples and may prove useful in the study of the epidemiology of plant pathogens or air pollution with particulate matter.     

Detection of airborne lactococcal bacteriophages in cheese manufacturing plants

The dairy industry adds starter bacterial cultures to heat-treated milk to control the fermentation process during the manufacture of many cheeses. These highly concentrated bacterial populations are susceptible to virulent phages that are ubiquitous in cheese factories. In this study, the dissemination of these phages by the airborne route and their presence on working surfaces were investigated in a cheese factory. Several surfaces were swabbed, and five air samplers (polytetrafluoroethylene filter, polycarbonate filter, BioSampler, Coriolis cyclone sampler, and NIOSH two-stage cyclone bioaerosol personal sampler) were tested. Samples were then analyzed for the presence of two Lactococcus lactis phage groups (936 and c2), and quantification was done by quantitative PCR (qPCR). Both lactococcal phage groups were found on most swabbed surfaces, while airborne phages were detected at concentrations of at least 10(3) genomes/m(3) of air. The NIOSH sampler had the highest rate of air samples with detectable levels of lactococcal phages. This study demonstrates that virulent phages can circulate through the air and that they are ubiquitous in cheese manufacturing facilities.     

Determination of the collection efficiency of a microbial air sampler

The Biotest RCS Plus air sampler was compared with the well-established Casella slit sampler for the quantitative analysis of the microbiological content of air. The results of the tests reported here show that the RCS Plus sampling efficiency is similar to that of the Casella sampler over the range of particles likely to be encountered in the environment. For particles less than 4 μm down to the sub-micronic sizes the efficiency of sampling falls off only gradually so that the efficiency of sampling for 1·0 μm particles is only reduced to about 50%. The ability to pre-select 10 different volumes (from 1 to 1000 1) enables the samplers to be used for measuring a wide range of concentrations of airborne micro-organisms in a variety of locations.     

Performance of the Coriolis air sampler,a high-volume aerosol-collection system for quantification of airborne spores and pollen grains

The Coriolis δ air sampler manufactured by Bertin Technologies (France) is a continuous air sampler, dedicated to outdoor monitoring of airborne spores and pollen grains. This high-volume sampler is based on patented Coriolis technology delivering a liquid sample. The air is drawn into a conical vial in a whirling type motion using suction; particles are pulled against the wall by centrifugal force. Airborne particles are separated from the air and collected in a liquid medium. This innovative solution allows rapid analysis by several techniques including PCR assay and serological assay in order to measure the antigenicity/allergenicity of pollen grains and fungal spores. Also, traditional counting of pollen grains or taxa identification by optical microscopy can be done. A study has been carried out by the Health Protection Agency (HPA), Porton Down, UK, to measure the physical efficiency of the Coriolis air sampler. The physical efficiency of the sampler for collection of micro-organism-laden particles of various sizes has been compared with that of membrane filter samplers using the techniques described by ISO 14698-1. The Coriolis was operated simultaneously with membrane filter samplers in a controlled room where they were challenged with uniform-sized particles of different diameters containing bacterial spores. For the larger particle sizes, it was found that the physical efficiency of the Coriolis was 92% for 10-μm particles. The biological performance of the Coriolis in the collection of airborne fungal spores and pollen grains was evaluated in comparison with a Hirst spore trap (one-week tape-on-drum type sampler) which is one of the most frequently used traps in the measurement of outdoor pollen grain concentrations. The advantages and limitations of both technologies are discussed. The Coriolis was operated simultaneously with a Hirst spore trap in the sampling station of Réseau National de Surveillance Aérobiologique, France (RNSA); the pollen grain and fungal spore counts were analysed by optical microscopy. The pollen grain count m⁻³ collected was compared for both devices. The dispersion values were obtained and statistical analysis was carried out. This study shows that the Coriolis air sampler provided equivalent recovery of pollen grain and fungal spores compared with the volumetric trap standard method (not significantly different, W test, α = 0.05). Nowadays, the French-led project, acronym MONALISA, with financial support from the European Commission––Life-Environment (LIFE05 ENV/F/000068), is testing this innovative air sampler in order to measure the antigenicity/allergenicity of the main aeroallergen particles, i.e. Betula (birch), Poaceae (grasses), Parietaria (pellitory), Olea spp (olive tree), and Artemisia (mugwort) pollen grains, and Alternaria (fungal spores) to validate a new approach of monitoring instead of quantifying pollen grains by their morphology. The robustness and efficiency of the MONALISA system is being demonstrated at a national level throughout Europe in eight different countries with different bio-climatic and topography characteristics: France, UK, Finland, Poland, Spain, Portugal, Switzerland, and Italy.     

Airborne Influenza A Is Detected in the Personal Breathing Zone of Swine Veterinarians

The 2009 H1N1 pandemic emphasized a need to evaluate zoonotic transmission of influenza A in swine production. Airborne influenza A virus has been detected in swine facilities during an outbreak. However, the personal exposure of veterinarians treating infected swine has not been characterized. Two personal bioaerosol samplers, the NIOSH bioaerosol sampler and the personal high-flow inhalable sampler head (PHISH), were placed in the breathing zone of veterinarians treating swine infected with either H1N1 or H3N2 influenza A. A greater number of viral particles were recovered from the NIOSH bioaerosol sampler (2094 RNA copies/m³) compared to the PHISH sampler (545 RNA copies/m³). In addition, the majority of viral particles were detected by the NIOSH bioaerosol sampler in the >4 μm size fraction. These results suggest that airborne influenza A virus is present in the breathing zone of veterinarians treating swine, and the aerosol route of zoonotic transmission of influenza virus should be further evaluated among agricultural workers.     

Portable Sampler for Microorganisms in Incinerator Stack Emissions

To obtain reliable information on viable microbial cells in incinerator stack emissions, a new sampling device has been developed that will concentrate microorganisms from large quantities of stack emissions into a small quantity of 0.067 m phosphate buffer. The simple, portable sampler provides a method for qualitative, nonisokinetic sampling, adjustable to isokinetic conditions that will yield quantitative results.     

Inactivation of Viruses in Bubbling Processes Utilized for Personal Bioaerosol Monitoring

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 Hank's 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.     

Inactivation of viruses in bubbling processes utilized for personal bioaerosol monitoring

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 Hank's 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.     

Evaluation of specific activity of artifical and natural radionuclides in the sink of aerosol matter into forest ecosystems

A new procedure is proposed for the investigation of atmospheric radioactivity in the surface air layer through evaluation of specific activity of artificial and natural radionuclides in the aerosol sink. Dry deposition of aerosol particles is described. The collection of aerosol is carried out using a passive sampler in which chemically inert fibrous and powdered materials are used as a sorption substrate. Analysis of experimental results characterizing the features of radionuclide distribution in the aerosol sink during their introduction into a coniferous tree stand is presented.     

Using a bioaerosol personal sampler in combination with real-time PCR analysis for rapid detection of airborne viruses

We have recently developed a new personal sampler and demonstrated its feasibility for detection of viable airborne microorganisms including bacteria, fungi and viruses. To accelerate the time-consuming analytical procedure involving 2-5 days of biological testing, we employed a real-time PCR protocol in conjunction with the personal sampler for collection of airborne viruses. The advantage of this approach is that if the presence of a particular pathogen in the air is detected by the PCR, the remaining collecting liquid can be further analysed by more time-consuming biological methods to estimate the number of airborne infectious/live microorganisms. As sampling of bioaerosols in natural environments is likely to be associated with substantial contamination by a range of microorganisms commonly existing in an ambient air, an investigation of the specificity of detection by targeted PCR analysis is required. Here we present the results of the study on the detection of Influenza virus in the ambient air contaminated with high concentrations of bacteria and fungi using real-time PCR protocol. The combined sampling PCR detection method was found to be fully feasible for the rapid ( approximately 2.5 h) and highly specific (no cross-reactivity) identification of the labile airborne virus in the air containing elevated concentrations of other microorganisms.     

Novel Multi-Slit Large-Volume Air Sampler

Scientific investigators who are interested in the various facets of airborne transmission of disease in research laboratories and hospitals need a simple, continuous, high-volume sampling device that will recover a high percentage of viable microorganisms from the atmosphere. Such a device must sample a large quantity of air. It should effect direct transfer of the air into an all-purpose liquid medium in order to collect bacteria, viruses, rickettsia, and fungi, and it should be easy to use. A simple multi-slit impinger sampler that fulfills these requirements has been developed. It operates at an air-sampling rate of 500 liters/min, has a high collection efficiency, functions at a low pressure drop, and, in contrast to some earlier instruments, does not depend upon electrostatic precipitation at high voltages. When compared to the all-glass impinger, the multi-slit impinger sampler collected microbial aerosols of Serratia marcescens at 82% efficiency, and aerosols of Bacillus subtilis var. niger at 78% efficiency.     

Quantifying the relationship between airborne pollen and vegetation in the urban environment

The goal of this study was to quantitatively assess the relationship linking vegetation and airborne pollen. For this, we established six sampling stations in the city of Thessaloniki, Greece. Once every week for 2 years, we recorded airborne pollen in them, at breast height, by use of a portable volumetric sampler. We also made a detailed analysis of the vegetation in each station by counting all existing individuals of the woody species contributing pollen to the air, in five zones of increasing size, from 4 to 40 ha. We found the local vegetation to be the driver of the spatial variation of pollen in the air of the city. Even at very neighbouring stations, only 500 m apart, considerable differences in vegetation composition were expressed in the pollen spectrum. We modelled the pollen concentration of each pollen taxon as a function of the abundance of the woody species corresponding to that taxon by use of a Generalized Linear Model. The relationship was significant for the five most abundantly represented taxa in the pollen spectrum of the city. It is estimated that every additional individual of Cupressaceae, Pinaceae, Platanus, Ulmus and Olea increases pollen in the air by approximately 0.7, 0.2, 2, 6 and 5%, respectively. Whether the relationships detected for the above pollen taxa hold outside the domain for which we have data, as well as under different environmental conditions and/or with different assemblages of species representing them are issues to be explored in the future.     

Enumeration of airborne molds in some indoor environments of Madras city (India) by cultural and non-cultural volumetric samplers

The air mycoflora of six indoor environments in Madras city (India) has been investigated by sampling air with an Andersen sampler and a Burkard personal sampler. Forty-eight species assignable to 24 genera were recorded by Andersen sampler. Spores belonging to 14 genera in addition toPenicillium andAspergillus were identified from Burkard trap slides. Species ofAspergillus, Penicillium, Mucor andRhizopus were most frequently isolated in considerable numbers. As a single genusAspergillus ranked first followed byPenicillium at some sites, andCladosporium at some other sites. The predominance ofPenicillium andAspergillus was also confirmed by Burkard trap data. Spores belonging toGanoderma, Nigrospora, Epicoccum, andTetraploa were recorded only by Burkard sampler, thereby suggesting the necessity of using two complimentary spore traps, cultural and non-cultural, in any aerobiological investigation.     

A portable, low-cost, multipurpose, surface-subsurface plankton sampler

This note describes a portable, low-cost, pump-based, multi-purpose,surface–subsurface, phytoplankton and zooplankton sampler.It is self-powered by a small 12 V DC battery, and is portableand ideal for use from a small boat in a river, estuary, orsea. The sampler is equipped with a very sensitive microprocessor-controlledflow sensor for precise determination of the volume of waterprocessed by the sampler. A study was carried out to evaluatethe performance of this sampler in comparison to the conventionaltowed plankton net. The results of this study suggest that thispump-based sampler is as efficient in collecting plankton asusing conventional plankton nets, with little damage to theorganisms.     

Measurement of resuspended aerosol in the Chernobyl area

Results of measurements of the resuspended radioactive aerosols in the Chernobyl area are presented which were obtained soon after the Chernobyl reactor accident and in a European project in 1992–1993. The measurements were carried out with the intention of obtaining a data base for dose assessment of resuspended radioactive particles. Potential significant dose contributions may result from inhalation and secondary contamination due to resuspended radionuclides. In this first article of a series of three papers, the instrumentation and the measurement uncertainties are discussed. An effort was made to sample quantitatively giant aerosol particles (particles larger than 10 μm aerodynamic diameter) as well. The comparison of the samplers shows, in general, an agreement of concentration measurements of ¹³⁷Cs and ⁷Be within a factor of two. One sampler was identified with larger discrepancies and needs additional investigation of its sampling characteristics; for another device, the recalibration of the analysing system is recommended. Ordinary integrating samplers have a loss of about 30% in ¹³⁷Cs activity compared to an isokinetic sampler collecting giant particles as well. The mean ratio of ¹³⁷Cs activity concentration between an instrument sampling only particles larger than 10 μm and an ordinary integrating sampler is 0.39 ± 0.15 during anthropogenic-enhanced resuspension. These findings demonstrate the significant contribution of giant particles to resuspended airborne radioactivity. The results of this study concerning integral measurements during wind-driven resuspension proved to be in good agreement with previously published data on resuspension. Received: 15 May 1997 / Accepted: 4 August 1997