The objective of this study was to evaluate the efficiencies and suitability of samplers for airborne microorganisms and dust, which could be used in practical livestock houses. Two studies were performed: 1) Testing impaction and cyclone pre-separators for dust sampling in livestock houses; 2) Determining sampling efficiencies of four bioaerosol samplers for bacteria and virus. Study 1. The overloading problem of the EU reference impaction pre-separator (IPS) was tested in layer houses and compared with cyclone pre-separators (CPS) for sampling PM10 and PM2.5. Study 2. Physical and biological efficiencies of Andersen 6-stage impactor, all glass impinger (AGI-30), high air flow rate sampler OMNI-3000, and MD8 with gelatin filter were investigated for collecting aerosolized bacteria, Enterococcus faecalis, Escherichia coli, Campylobacter jejuni and Mycoplasma synoviae and live Gumboro vaccine virus. A tracer (uranine) was used to determine physical efficiencies and bioaerosol deposition. The study was done in a HEPA isolator (volume: 1.3 m3). The results show the PM10 IPS did not become overloaded in 24 h measurements in layer houses, whereas PM2.5 IPS became overloaded within 1 h. CPS did not become overloaded during 48 h sampling of both dust fractions. The OMNI-3000 (62%) had lower physical efficiency than the MD8, while the other samplers had similar efficiencies as MD8. All the bioaerosol samplers had high biological efficiencies for all four bacterial species, except for C. jejuni (1%) when measured with the OMNI-3000 and for E. coli (38%) and C. jejuni (2%) when measured with the MD8. The biological efficiencies of the Andersen impactor (61%), the AGI-30 (90%) and the MD8 (163%) were not significantly different from 100% for collecting the aerosolized virus. However, the biological efficiency (23%) of the OMNI-3000 was significantly lower than 100%

Aarnink, A.J.A.

Groot Koerkamp, P.W.G.

Jong, M.C.M., de

Zhao, Y.

English

Jong, de, M.C.M.

NARCIS 

Airborne microorganisms and dust from livestock houses

Wageningen Yield 

AIRBORNE MICROORGANISMS AND DUST FROM LIVESTOCK HOUSES 
 
Zhao, Y. 1,2,3, Aarnink, A.J.A.1, de Jong, M.C.M.2, Groot Koerkamp, P.W.G.3 
 
 
1 Wageningen UR Livestock Research, the Netherlands; 
 2 Quantitative Veterinary Epidemiology, Wageningen University, the Netherlands; 
 3 Farm Technology Group; Wageningen University, the Netherlands 
 
 
 
SUMMARY 
 
The objective of this study was to evaluate the efficiencies 
and suitability of samplers for airborne microorganisms 
and dust, which could be used in practical livestock 
houses. Two studies were performed: 1) Testing 
impaction and cyclone pre-separators for dust sampling in 
livestock houses; 2) Determining sampling efficiencies of 
four bioaerosol samplers for bacteria and virus.  
 
Study 1. The overloading problem of the EU reference 
impaction pre-separator (IPS) was tested in layer houses 
and compared with cyclone pre-separators (CPS) for 
sampling PM10 and PM2.5. Study 2. Physical and biological 
efficiencies of Andersen 6-stage impactor, all glass 
impinger (AGI-30), high air flow rate sampler OMNI-3000, 
and MD8 with gelatin filter were investigated for collecting 
aerosolized bacteria, Enterococcus faecalis, Escherichia 
coli, Campylobacter jejuni and Mycoplasma synoviae and 
live Gumboro vaccine virus. A tracer (uranine) was used to 
determine physical efficiencies and bioaerosol deposition. 
The study was done in a HEPA isolator (volume: 1.3 m3).  
 
The results show the PM10 IPS did not become overloaded 
in 24 h measurements in layer houses, whereas PM2.5 IPS 
became overloaded within 1 h. CPS did not become 
overloaded during 48 h sampling of both dust fractions. 
The OMNI-3000 (62%) had lower physical efficiency than 
the MD8, while the other samplers had similar efficiencies 
as MD8. All the bioaerosol samplers had high biological 
efficiencies for all four bacterial species, except for C. 
jejuni (1%) when measured with the OMNI-3000 and for 
E. coli (38%) and C. jejuni (2%) when measured with the 
MD8. The biological efficiencies of the Andersen impactor 
(61%), the AGI-30 (90%) and the MD8 (163%) were not 
significantly different from 100% for collecting the 
aerosolized virus. However, the biological efficiency (23%) 
of the OMNI-3000 was significantly lower than 100%. 
 
INTRODUCTION 
 
Airborne microorganisms in livestock houses attach to dust 
particles. They can emit to the ambient air through the 
ventilation exhausts. Emission of pathogenic 
microorganisms pose infection risk to animals in other 
nearby livestock units and/or to humans. Lab-scale 
experiments have confirmed short distance airborne 
transmission of some microorganisms from animal to 
animal: it was found that healthy animals kept physically 
but not aerially separated from infected animals became 
infected (Berthelot-Herault et al. 2001; Brockmeier and 
Lager 2002). Also, the porcine reproductive and 
respiratory syndrome virus (PRRSV) was collected 
kilometers away from the source farm (Otake et al. 2010). 
However, to date these findings still have not 
incontrovertibly been linked to long distance airborne 
transmission of microorganisms between farms. 
Furthermore, there is still lack of knowledge about the role 
of dust in airborne transmission. Knowledge gaps in 
airborne transmission need to be filled and effective 
transmission control technologies require to be developed 
(Zhao et al. 2011a). Therefore, investigations on airborne 
microorganisms and dust should be carried out, such as 
source identification, suspension, physical and biological 
decay in airborne transportation, deposition in respiratory 
tracts, and infection in recipients. Almost all the above 
mentioned investigations cannot be performed without 
accurately and precisely measuring airborne 
microorganisms and dust from livestock production 
systems.  
 
Measurements of airborne microorganisms is performed 
with bioaerosol samplers applying different principles, 
including impaction, impingement, cyclone forces and 
filtration. Because airborne microorganisms may either be 
physically miss-collected or  biologically inactivated by 
various sources of stresses during sampling, the 
efficiencies of these samplers are generally known to be 
imperfect. To date, the efficiencies of the samplers for 
collecting different microbial species have not been well 
established. Notably, there is no standard protocol for 
sampling airborne microorganisms that specifies the 
requirements for hardware and also the procedures 
immediately prior, during and after the sampling. The lack 
of a protocol makes it difficult to interpret and compare 
the results of different studies. The sampling protocol for 
collecting PM10 and PM2.5 in ambient air has been 
legislated by the EU commission and US EPA (European 
Commission 1998; 2005a; US EPA 2010). These sampling 
techniques, however, might not be suitable to sample dust 
in livestock houses, because the concentrations and 
particle sizes of dust in livestock houses are profoundly 
different from those in the ambient air, and this may 
compromise the efficiency and accuracy of the sampling. 
There is therefore an urgent need to develop a technique 
and eventually a protocol suitable for sampling dust in 
livestock houses.  
 
The objective of this study was to investigate the 
suitability and efficiency of bioaerosol and dust samplers 
for measuring airborne microorganisms and dust from 
livestock production systems. In details, experiments were 
carried out to: 
 investigate the overloading problem of EU reference 
dust sampler with an impaction pre-separator (IPS), 
when used for measuring PM10 and PM2.5 in the dusty 
environment of layer houses; evaluate the cyclone 
pre-separator (CPS) as a reference equivalent pre-
separator for PM sampling in the dusty environment 
of livestock houses following the EU standard 
procedure. 
 assess the sampling efficiencies of four bioaerosol 
samplers (Andersen 6-stage impactor, AGI-30, OMNI-
3000, and MD8 with a gelatine filter) on measuring 
aerosolized E. faecalis, E. coli, M. synoviae, C. jejuni, 
and Gumboro vaccine virus. 
 
MATERIAL AND METHODS 
 
Evaluation of IPS and CPS in livestock houses 
 
Sampler and pump 
 
EU reference dust sampler consists an IPS and a filter 
holder. In the IPS, a flat impaction plate was rubbed with 
grease and placed under eight impaction nozzles. Larger 
particles strike the plate at speed and are retained on the 
impaction plate because of their inertia. The smaller target 
particles (PM10 or PM2.5) are carried along in the air 
stream and are collected on the downstream filter. The 
airflow rate through the inlet head of an IPS is 2.3 m3 h-1. 
More detailed descriptions of the EU sampler can be found 
in EU documentations (European Commission 1998; 
005a). 
filter 
older. The airflow used for a CPS is set at 1 m3 h-1. 
tant 
ir passing through the filter. The unit of dust 
as expressed as μg m-3. 
nd CPS 
d by a treatment pre-separator, 
e pre-separator was overloaded. See the study by Zhao 
h pair of measurements we used one IPS (as 
e reference sampler) and two CPSs (as the candidate 
mpler).  
 
 
2
 
The candidate sampler consists of an air inlet head, a CPS 
(URG corp., US) and a filter holder. The CPS uses the 
centrifugal principle to separate large particles trapped in 
a dust collector. PM10 or PM2.5 are conveyed in the air 
stream and collected by a glass fibre filter in the 
h
 
Charlie HV pumps (Ravebo Supply b.v., Brielle, the 
Netherlands) were used to suck air through the two types 
of samplers. These pumps are able to maintain cons
airflow (< 2% nominal value) during dust sampling.   
Mass of each filter before and after sampling was 
measured. The PM10 or PM2.5 concentration was 
calculated by dividing the mass difference by the total 
volume of a
w
 
Overloading of IPS a
 
When a pre-separator becomes overloaded, it’s greased 
plate (of IPS) or dust collector (of CPS) is no longer able 
to separate larger particles from the incoming air stream. 
Therefore, dust particles in the whole size range are 
transported to the downwind filter. This results in an 
overestimation of PM10 or PM2.5 concentration. 
Understanding above mentioned phenomenon, the 
overloading of a pre-separator was determined in this 
study by comparing the PM concentration collected with a 
sampler without cleaning the pre-separator during 
sampling (control) to that collected by a sampler with 
regular cleaning the pre-separator (treatment). When the 
dust concentration measured by a control pre-separator is 
higher than that measure
th
et al. (2009) for details.  
 
Validating CPS 
 
To be qualified as the reference equivalent device, CPS 
should be able to perform precise and accurate 
measurements. The equivalent test was carried out 
following the EU standard procedure as required 
(European Commission 1998). Ninety-six pairs of 24 h 
measurements, 48 for PM10 and 46 for PM2.5, were 
conducted in various environments: livestock houses 
(three fattening pig houses, one broiler house and one 
dairy barn); an industrial workplace; and in the ambient 
air. For eac
th
sa
 
 
Sampling efficiency of bioaerosol sampler 
 
Sampling efficiency includes physical and biological 
efficiency. The physical efficiency of a sampler reflects 
how well the sampler aspire, transport and retain the 
airborne particles from the ambient air to its collection 
medium. The biological efficiency reflects how well the 
viability of the microorganisms is maintained during 
sampling. In this study, the physical and biological 
efficiencies of four bioaerosol samplers (Andersen 6-stage 
impactor, AGI-30, OMNI-3000, and MD8 with gelatin filter) 
on collecting five microbial species (E. faecalis, E. coli, C. 
jejuni, M. synoviae, and Gumboro vaccine virus) were 
investigated. This was done by aerosolizing the microbial 
suspensions (with or without a physical tracer) in an HEPA 
isolator, and by collecting the aerosolized microorganisms 
with the samplers. The physical efficiency was calculated 
based on the amount of tracer collected; and the 
biological efficiency was calculated based on the 
microorganisms/tracer ratio. More details can be found in 
Zhao et al. (2011b; 2011c; 2011d). 
 
RESULTS AND DISCUSSION 
 
Dust sampler 
 
Overloading of IPS and CPS 
 
The results show that PM2.5 IPS was overloaded within 8 h 
when used for sampling dust in a layer room. The 
overloading of PM2.5 IPS was not solved even with a 1 h 
plate cleaning interval (Zhao et al. 2009), thus it cannot 
be used for PM sampling in such a dusty environment. 
Compared to IPS, PM2.5 CPS was more resistant to high 
dust concentrations. It is shown that the PM2.5 CPS did not 
become overloaded during 24 h sampling. Both PM10 IPS 
and PM10 CPS had no overloading problem.  
 
Validating CPS 
 
The results show that both PM10 and PM2.5 CPSs were 
qualified as the reference equivalent pre-separator for the 
EU IPS, when these candidate samplers were used in 
environments with low dust concentrations (<100 μg m-3 
for PM10, and working place/ambient air for PM2.5). The 
relative two side 95% confident interval (CI95) of PM10 
CPS (6%) is almost within the required value (5%); and 
the PM10 concentrations measured by the CPS was within 
the acceptance envelope:  (y = x ± 10) μg m-3, where y is 
the PM concentration measured by CPS and x is the PM 
concentration measured by IPS. The absolute CI95 of 
PM2.5 CPS (2.3 μg m-3) is within the required value of 5 μg 
m-3; and the PM2.5 concentrations measured by the CPS 
was within the acceptance envelop:  (y = x ± 10) μg m-3. 
 
The PM10 concentrations measured by PM10 CPS were 
systematically lower than those measured by IPS in less 
dusty environments, and were higher in dusty 
environments. Therefore, the PM10 concentration 
measured by CPS should be corrected (Equations 1 and 
2).  
 
xy 09.1  (x ≤ 223 µg m-3)           (1), 
5.5783.0  xy (x > 223 µg m-3)                  (2) 
y: is the calibrated concentration, µg m-3; x: is the 
concentration measured with CPS, µg m-3.  
 
Bioaerosol sampler 
 
Physical and biological efficiency 
 
The physical efficiencies of the Andersen impactor and the 
AGI-30 were not different from the high efficient sampler - 
MD8. However, the physical efficency of the OMNI-3000 
(62%) was signficantly lower than that of the MD8. The 
biological efficiencies of the samplers on collecting all 
microbial species were not different from 100%, except 
for C. jejuni (1 ± 1%) and Gumboro vaccine virus (23 ± 
10%) when sampled by OMNI-3000, and for C. jejuni (2 ± 
1%) and E. coli (38 ± 10%) when sampled by MD8. The 
significant lower efficiencies suggested that these 
microbial species were inactivated due to sampling stress 
from samplers. 
 
The total sampling efficiency (combination of physical and 
biological efficiencies) and the detection limit were 
calculated from the efficiency data and are listed in Table 
1. This information may be helpful for selecting samplers 
suitable for practical measurements. The Andersen 
impactor and the AGI-30 are suitable for sampling all 
microbial species because their total efficiencies are high. 
The MD8 is suitable for sampling E. faecalis, M. synoviae 
and Gumboro vaccine virus, but not E. coli and C. jejuni. 
Although the OMNI-3000 has low sampling efficiencies of 
62% for E. faecalis, E. coli and M. synoviae, and 14% for 
Gumboro vaccine virus, it could still be a suitable sampler 
because its high air flow rate gives low detection limits. 
The OMNI-3000 cannot be used for C. jejuni because this 
species would be seriously inactivated by sampling stress. 
The Andersen impactor has high sampling efficiency on 
Gumboro vaccine virus (100%), however, its detection 
limit (4.1 log10 EID50 m-3) is highest among all samplers, 
because virus was lost in air sample handling (Zhao et al. 
2011b). 
 
Table 1. Total sampling efficiency and detection limit of bioaerosol samplers. 
 E. faecalis E. coli C. jejuni M. synoviae Gumboro 
Sampling efficiency (%)1      
Andersen2 100 100 100 100 100 
AGI-30 100 100 100 100 100 
OMNI-3000 62 62 0.6 62 14 
MD8 100 38 2 100 100 
Detection limit3      
Andersen2 3.9 3.9 3.7 3.8 4.14 
AGI-30 3.9 4.2 3.8 4.0 3.3 
OMNI-3000 2.5 2.5 4.5 2.7 2.5 
MD8 4.1 4.4 5.4 4.3 2.9 
1 100% means that in our study the measured efficiency was not significantly different from 100%. 
2 Physical and biological efficiencies of the Andersen impactor were set to 100% because it collected similar amounts of viable microorganisms as the 
AGI-30.  
3 Detection limit was calculated based on a 2 min sampling duration. The unit of DL is log10 CFU m-3 for bacteria, and log10 egg infective dose 50% 
(EID50) m-3 for virus. 
4 Detection limit was calculated by assuming agar plates of Andersen impactor were rinsed 1 h after sampling. 
 
CONCLUSIONS 
 
EU reference PM2.5 IPS cannot be used for dust sampling 
in livestock production systems because of overloading. 
PM10 and PM2.5 CPSs are equivalent to IPS when used in 
environments with low dust concentrations, and are more 
resistant to dusty environments. Therefore, CPSs are 
promising devices for dust sampling in livestock 
production systems.   
The physical and biological efficiencies of the bioaerosol 
samplers vary. In order to perform accurate measurement 
of airborne microorganisms, the efficiency of a sampler 
should be investigated beforehand. In this study, we 
found OMNI-3000 was not suitable for sampling C. jejuni 
and MD8 was not suitable for C. jejuni and E. coli. 
 


Name not available

Airborne microorganisms and dust from livestock houses

Abstract

Similar works

Full text

Available Versions

NARCIS

Wageningen Yield

Name not available