Environmental Engineering Reference
In-Depth Information
Table 9.1
Devices/Techniques Used for Viable/Culturable Bioaerosol Sampling
Recommended
sampling time
(min)
Sampling rate
(L/min)
Sampler type
Operating principle
Slit or slit-to-agar
impactor
Impaction onto solid
culture medium on
rotating surface
30-700
1-60, Depending
on model and
sampling
circumstances
Sieve impactors
Single-stage,
portable impactor
Impaction onto solid
culture medium in
a “rodac plate”
90 or 180
0.5-5
Single-stage (N-6)
impactor
Impaction onto solid
culture medium in
a 10 cm plate
28.3
1-30
a
Two-stage
impactor
As above
28.3
1-30
a
Multiple-stage
impactor
As above
28.3
1-30
a
Centrifugal
Impaction onto solid
culture medium in
plastic strips
40±
0.5
Impingers
All glass/AGI-30
Impingement into
liquid; jet 30 mm
above impaction
surface
12.5
1-30
All glass/AGI-4
As above; jet 4 mm
above impaction
surface
12.5
1-30
Filters
Cassette
Filtration
1-2
5-60
a
Contemporary practice is 1 to 5 minutes.
Source:
From Chatigny, M.A. et al.,
Air Sampling Instruments for Evaluation of Atmospheric Con-
taminants
, ACGIH, Cincinnati, 1989, 10. With permission.
particle collection and the efficiency with which the viability of collected
microorganisms is preserved.
Both multistage and single-stage impactors have been suggested as ref-
erence samplers to which results of other samplers are compared. Because
of its widespread use in IAQ research and problem building investigations,
the single-stage (Andersen N-6) sampler (
Figure 9.8
)
has become the
de facto
reference sampler. It collects airborne particles onto a nutrient agar plate
through an orifice plate with 400 tiny holes at a standard flow rate of 1 CFM
(28.3 L/min); sampling durations of 1 to 2 minutes are commonly used.
Though the most widely used bioaerosol sampling devices, cultura-
ble/viable samplers have significant limitations. The most notable of these
