| Summary: | 碩士 === 國立成功大學 === 環境醫學研究所 === 86 === Bioaerosol samplers had been widely used in research of
industrial hygiene and environmental science. In this study,
three samplers of collecting viable bioaerosols were selected to
evaluate their collection efficiency. It was also aimed to
investigate whether the concentrations found were representative
to human exposure and to characterize the difference of sampling
results providedby various samplers.Three commercially-available
samplers were included, namelyAndersen N6 single-stage sampler
(N6), Burkard single-stage sampler (Bk), andAGI-30 impinger
(AGI). In addition, Andersen six-stage sampler (6-STG) wasused
to construct the size-distribution of airborne-bioaerosols and
toestimate the theoretical collection efficiency of each
sampler. By adoptingthe wind-tunnel data of IOM personal aerosol
sampler and the characteristicsof impinger, an Inhalable
Bioaerosol Impinger (IBI) was developed as a reference sampler
to estimate the relative collection efficiency for
inhalablebioaerosols of each sampler.The break-through rates
were 5.49%~7.47% for IBI and 0.78%~1.20% for AGI inthe field
tests. They were acceptable according to the standard set by the
Council of Labor Affairs of Taiwan, ROC, for the samplers of
chemical compounds.The sampling activities were conducted in 12
homes and 5 locations within a textile plant in Tainan City,
with all 5 samplers (N6, Bk, AGI, IBI, and 6-STG) being placed
side-by-side to each other. Duplicates for each type of sampler
were collected each time throughout the 30 minute sampling
period except for the 6-STG. After proper incubation given for
fungal and bacterial growth respectively, morphological
identification were applied to achieve the bioaerosol
concentration on each sampling plate; the unit is colony forming
unit per cubic meter of air, CFU/m^3.Statistical analysis shows
that concentrations found from 3 samplers (N6, Bk, and AGI) are
significantly different from each other for total bacteria and
some fungal genuses. The measured relative collection
efficiencies for Bk and N6 compared to AGI are 1.05 and 1.40 in
fungi and 1.64 and 1.64 in bacteria. However, the theoretical
collection efficiency calculated based on size-distribution
curve and the characteristic of each sampler indicates that
values for Bk and N6, compared to AGI, should be 0.41 and 0.86
for fungi and 0.53 and 0.95 for bacteria. The ratios of the
measured to theoretical concentrations for N6, Bk, and AGI are
0.41, 1.85, and 0.82 respectively for fungi and 0.72, 3.74, and
1.36 for bacteria. The variations shown among the samplers
examined might have resulted from the difference existing in the
flow rate, size of particles collected, degree of wall loss,
effect of wind speed on the thin-wall probe, and biological and
physical characteristics of bioaerosols collected in each field
conditions. Whether these variations in both the measured and
theoretical collection efficiency can be expected considering
the differences existing their original design require further
investigation. The AGI shows better efficiency in collection
inhalable fungal aerosol; the relative collection efficiencies
of N6, Bk, and AGI, based on comparison to IBI, were 31%, 50%,
and 51%. Bk seems to perform better in collecting inhalable
bacteria; compared to IBI, the relative collection efficiencies
of N6, Bk, and AGI are 12%, 24%, and 23% respectively. These
efficiencies are all far below 100%, and therefore none of these
3 samplers can be regarded as ideal to present the true human
exposure levels to the bioaerosols of concern. Focus of further
studies should be directed to design a proper samplers to better
reflect the exposure of interest.
|
|---|
