| Bioaerosols play an important role in the natural environment.Not only do they affect the physical and chemical changes in the atmosphere,they also impact on human health.Accurate detection and analysis of the component of environmental bioaerosols cannot be conducted without efficient sampling and enrichment tools for bioaerosols-bioaerosol samplers.The performance of the bioaerosol sampler can directly affect the accuracy of the bioaerosol assessment.For this reason,it is important to conduct a comprehensive and accurate performance evaluation to reasonably select sampler models,scientifically calibrate sampling data,and design new bioaerosol samplers with better performance.Firstly,the basic performance of a self-developed high flow rate wet wall cyclone air particle sampler was evaluated.Then,based on the need for further evaluation,a method for rapid performance evaluation of bioaerosol samplers using solid polydisperse aerosols was developed.And an aerosol wind tunnel for evaluation of bioaerosol sampler,the Bioaerosol Sampling and Detection Evaluation Chamber,was developed.The performance of the above method and equipment was verified.Finally,the sampling performance of five bioaerosol samplers was evaluated in comparison using the newly developed method and the newly developed aerosol wind tunnel.In the preliminary evaluation of the high-flow wet-wall cyclone air particle sampler,the physical and biological sampling efficiency of the sampler were evaluated as well as the disinfection effect after sampling and the actual performance of the field aerosol sampling.The results showed that the cut off size of wet-wall cyclone air particle sampler sampling sodium chloride aerosols was approximately 1μm.The total biological sampling efficiencies were(25.47 ± 12.94)% and(16.34 ± 1.67)% for Serratia marcescens and Escherichia coli phage Phi X174,while the active biological sampling efficiencies were(42.98 ± 6.53)% and(24.24 ± 6.68)%,respectively.After the sampling of Serratia marcescens aerosol,hydrogen peroxide disinfection cleaning process could remove most of the biological components remaining in the high-flow wet-wall cyclone air particle sampler,with the rate of(99.73 ± 0.04)% for nucleic acid and(99.998± 0.001)% for cultivable bacteria.In the field sampling application,the cultivable bioaerosol detection limit of the high-flow wet-wall cyclone air particle sampler was(42.60 ± 11.60)times lower than that of the AGI-30,and the calculated air microbial concentration was(6.67 ± 1.57)times higher than that of Biostage.The high-flow wet-wall cyclonic air particle sampler has excellent aerosol sampling performance and is suitable for sampling of low concentration bioaerosols in the environment.However,these evaluation methods have more room for improvement in terms of stability,accuracy and evaluation content.In order to optimize the evaluation index and achieve a faster and more comprehensive physical sampling efficiency evaluation of aerosol samplers,a performance evaluation method based on solid polydisperse aerosols Arizona test dust for physical sampling efficiency of aerosol samplers was established.The study tested the dispersion of aerosolized Arizona test dust,the accuracy of quantifying polydisperse solid particles evaluating by a laser particle sizer,the stability and uniformity of Arizona test dust in the aerosol evaluation chamber,and the performance of the AGI-30 and Bio Sampler aerosol samplers evaluating by polydisperse and monodisperse aerosols.The results show the absence of aggregation and good dispersibility of the aerosolized arizona test dust.The accuracy and reproducibility of particle quantification method were successfully established in the optical concentration range of 10%-40%,with deviation within 10%.The stability and homogeneity of the dust concentration in the aerosol experimental chamber under different experimental procedures were also achieved.The results of the physical sampling efficiency evaluation using polydisperse aerosol method showed high agreement with monodisperse aerosol method,which demonstrated the accuracy of our new established method.This evaluation method is able to achieve a comprehensive physical sampling efficiency of aerosol samplers in a shorter period of time.In order to provide a more stable aerosol test platform,a laminar flow bioaerosol sampling and detection evaluation chamber was developed in this study,and the performance of the chamber was evaluated in terms of wind speed range,wind speed stability,aerosol uniformity and actual evaluation process.The test results show that the evaluation chamber can operate stably in the wind speed range of 0.57 m/s-5.47 m/s,and the evaluation section has well wind speed stability under the wind speed of 0.57 m/s and 2.22 m/s,and the maximum concentration deviation of 12 test points is less than 10%.The aerosol uniformity of polydisperse phosphate buffered saline(PBS)were outstanding at the test wind speed of 0.57 m/s and 2.22 m/s.In the particle size range of0.5-4 mm,the maximum concentration deviation was less than 10% for all 9 test points.In practical applications,Arizona test dust collected by the filter sampler at the two reference sampling points in the cross-section of evaluation chamber had good uniformity in the particle size range of 0.6-16.9 μm at a wind speed of 0.57 m/s,and the deviation from the mean value were all less than 10%.The aerosols sampling results at the reference sampling sites and the test sampling sites showed good agreement in the particle size range of 0.6-10.1 μm,and the deviations from the test were less than 10%.The bioaerosol sampling and detection evaluation chamber has good performance and can be used for the performance evaluation of bioaerosol samplers.Finally,5 bioaerosol sampling devices were compared and evaluated in this study.the physical sampling efficiency,biological sampling efficiency and long-term sampling performance of the test aerosol samplers were evaluated using a laminar flow bioaerosol sampling and detection chamber,as well as the newly established evaluation method of physical sampling efficiency of aerosol samplers based on solid polydisperse aerosols.The AGI-30 aerosol sampler has a wide particle size collection range,but evaporation of the sampling fluid made it unsuitable for long duration(>60 min)aerosol sampling.The Bio Sampler has a lower sampling efficiency for particles larger than 6 μm in size and a biological sampling efficiency close to that of the AGI-30 for short sampling periods.Although the biological activity of the microorganisms is higher for longer sampling periods than with the AGI-30,the evaporative of the sampling solution also makes it unsuitable for longer sampling periods.The two wet wall cyclone bioaerosol samplers are less efficient for particle sizes smaller than 2 μm and have lower biological sampling efficiencies than the AGI-30,but the larger sampling flow rates and the fluid retention capacity make them extremely advantageous for sampling low concentrations of bioaerosols in the environment and for prolonged sampling.The gelatin membrane sampler is close to the AGI-30 aerosol sampler in terms of biological sampling efficiency for bacteria.However,the bioactivity sampling efficiency for phages is lower than that of the AGI-30,and even lower for prolonged sampling.An understanding of the performance of these bioaerosol samplers will assist in the selection and use of bioaerosol samplers in practical applications.In this study,a more complete,rapid and accurate laboratory evaluation method for bioaerosol samplers was developed,which systematically evaluates the physical sampling efficiency,biological sampling efficiency,and long-term bioaerosol sampling capability of samplers.The new polydisperse solids aerosol and laser particle size method allows for a more rapid and economical evaluation of the physical sampling efficiency of aerosol samplers.The newly developed bioaerosol sampling and detection chamber provides a more stable and homogeneous aerosol environment.A variety of microbial testing strategies have been employed to provide a more comprehensive assessment of the bioaerosol sampler’s ability to sample a wide range of microorganisms. |
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