Field Performance of Portable Impactors when Enumerating Viable Bioaerosols

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1 Field Performance of Portable Impactors when Enumerating Viable Bioaerosols Gedi Mainelis 1 and Maosheng Yao 1, 2 1 Rutgers University, Dept. Env. Sciences, New Brunswick, NJ. mainelis@envsci.rutgers.edu 2 Yale University, New Haven, CT

2 Introduction Exposure to airborne microorganisms presents a serious health challenge Occupational environments (MWF, agriculture), indoor environments (offices and residences) Infectious, hypersensitivity diseases, toxic effects Natural disasters Effective bioaerosol monitoring and exposure assessment tools & techniques are urgently needed Comparative characteristics of many samplers are still unknown

Portable Microbial Samplers Becoming more popular Portable, easy to handle, high flow rates Insufficient data available on their physical and biological

3 Portable Microbial Samplers Becoming more popular Portable, easy to handle, high flow rates Insufficient data available on their physical and biological performance Lack of comparative performance data from field studies Lack of performance data may lead to exposure mischaracterization Portable Bioaerosol Samplers

4 Objective Continuation of our investigation of the portable sampler performance when sampling culturable bacteria and fungi Earlier studies Laboratory performance This study Field performance

5 Methods Portable Microbial Impactors Bio-Culture 120 L/min, 30 ml agar D 50 = 7 µm Microflow 120 L/min, 25 ml agar D 50 = 8.8 µm SMA MicroPortable 28.3/141.5 L/min, 25 ml agar D 50 = 4.8 µm

2 µm SAS Super 180 180L/min 40 ml agar D 50 = 2.

6 Methods Portable Microbial Impactors RCS High Flow 100 L/min, agar strip D 50 = 1.2 µm SAS Super L/min 40 ml agar D 50 = 2.1 µm Millipore Air Tester 140/180 L/min agar plate D 50 = 2.3 µm

7 Methods Portable Impactor Reference Sampler MAS L/min, 50 ml agar D 50 = 1.7 µm Gelatin filter 4 L/min, Button Inhalable Aerosol Sampler BioStage 28.3 L/min, 50 ml agar D 50 = 0.65 µm

8 Impactor nozzle Jet-to-plate distance, S Jet diameter, w

9 Comparison of Sampler Collection Efficiency with Particle Inhalation and Deposition in Human Lung Yao and Mainelis (2006), J. Exposure Analysis and Environ. Epi.

10 Portable Bioaerosol Samplers Relative Overall Performance Bioculture SMA Microflow SAS-180 Millipore Mair T RCS High Flow MAS-100 Gelatin Filter Aerodynamic diameter, m B. subtilis C. cladosporioides A. versicolor P. melinii E. coli P. fluorescens Relative Overall Efficiency, compared to BioStage Impactor

11 Methods Field environment Indoors and outdoors Two separate days Bacteria and fungi separately Growth conditions Room temperature 48 hrs for bacteria, 72 hrs for fungi Sampling parameters 5 min sampling time; 15 min for gelatin filter 5 repeats Simultaneous operation Performance relative to BioStage: Concentration from a portable sampler vs concentration from BioStage

12 Portable Bioaerosol Samplers Indoor Bacteria Sampling < Gelatin Filter BioStage RCS High Flow MAS-100 SAS Super 180 Millipore Air Tester SMA BioCulture Microflow Field Testing Day #1 Day #2 Cutoff Size, m Yao and Mainelis (2007) J. Occ. Environ. Hygiene Relative Overall Efficiency, REFF

13 Portable Bioaerosol Samplers Indoor Fungi Sampling Day #1 Day #2 < Cutoff Size, m Gelatin Filter BioStage RCS High Flow MAS-100 SAS Super 180 Millipore Air Tester SMA BioCulture Microflow Field Testing Yao and Mainelis (2007) J. Occ. Environ. Hygiene Relative Overall Efficiency, REFF

14 Portable Bioaerosol Samplers Outdoor Bacteria Sampling Day #1 Day #2 < Cutoff Size, m Gelatin Filter BioStage RCS High Flow MAS-100 SAS Super 180 Millipore Air Tester SMA BioCulture Microflow Field Testing Yao and Mainelis (2007) J. Occ. Environ. Hygiene Relative Overall Efficiency, REFF

15 Portable Bioaerosol Samplers Outdoor Fungi Sampling Day #1 Day #2 < Cutoff Size, m Gelatin Filter BioStage RCS High Flow MAS-100 SAS Super 180 Millipore Air Tester SMA BioCulture Microflow Field Testing Yao and Mainelis (2007) J. Occ. Environ. Hygiene Relative Overall Efficiency, REFF

16 Analysis Two-Way ANOVA for Sampling Day and Sampler Statistical significance of multiple pairwise Bonferroni comparisons relative to the BioStage impactor (reference) for Day#1 and Day #2 separately Portable Bioaerosol Samplers Statistical significance of multiple pairwise Bonferroni comparisons of the pooled portable impactor data (BioStage not included) Bacteria Indoors Sampling day Sampler p< p< Day 1 Day 2 SMA, BioCulture and Microflow different (lower) All samplers different (lower), except MAS- 100 SMA different (lower) compared to the SAS Super 180, the Millipore Air Tester and the MAS-100 Outdoors Sampling day Sampler p=0.73 p=0.006 Day 1 Day 2 None different None different MAS-100 different (higher) compared to the Millipore Air Tester Fungi Indoors Outdoors Sampling day Sampler Sampling day Sampler p=0.65 p=0.006 p=0.024 p= Day 1 Day 2 Day 1 Day 2 Millipore Air Tester and SMA different (lower) Millipore Air Tester and the SMA different (lower) None different Millipore Air Tester, SMA, and Microflow different (lower) The SMA different (lower) compared to the MAS-100; Microflow different (higher) compared to the Millipore Air Tester and the SMA RCS High Flow different (higher) compared to the Millipore Air tester and the SMA; MAS-100 different (higher) compared to the SMA

17 Portable Bioaerosol Samplers * * * * *, ++ *, Cutoff Size, d 50, m Gelatin Filter BioStage RCS High Flow MAS-100 SAS Super 180 Millipore Air Tester SMA BioCulture Microflow Field Testing R 2 = 0.16 Yao and Mainelis (2007) J. Occ. Environ. Hygiene Relative Overall Efficiency, REFF

18 Laboratory study R 2 = 0.6 Relative Overall Efficiency, REFF Cut-off size, d 50, m BioStage RCS High Flow MAS-100 SAS Super 180 Millipore Air Tester SMA BioCulture Microflow

20 Field Testing Single linear regression: Cut-off size, d 50 : R 2 = 0.16 (p=0.32) Jet-to-plate distance, S: R 2 = 0.53 (p=0.04) Multiple regression analysis Portable Bioaerosol Samplers R EFF = S 0.042d 50 R 2 = 0.83 (p= 0.012) Inclusion of other design parameters, such as jet velocity or dimensionless S/W (jet diameter over jet-to-plate distance), was not statistically significant

21 Conclusions Field performance varies depending on model Portable Bioaerosol Samplers Relative performance in a particular environment may vary from day to day Cut-off size gives an indication of a sampler s performance, but d 50 alone does not seem to be a sufficient predictor of a samplers performance in the field First empirical model to predict performance of portable samplers in the field was developed Results of the study could serve as a reference for field professionals selecting tools to assess bioaerosol exposure

22 Field Testing Ongoing investigation: Effect of sampling time on the recovery of airborne microorganisms Available results indicate that longer sampling time results in lower measured concentration for some samplers

23 Acknowledgement Dr. Maosheng Yao (currently at Yale University) This study was supported by the CDC/NIOSH CAREER grant K01-OH "Evaluation of Portable Samplers for Viable Bioaerosols.

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