Environmental Engineering Reference
In-Depth Information
Department of Housing and Urban Development (HUD) for conducting risk
assessments and clearance sampling in lead-based paint and lead-contami-
nated dust abatements. Guidance values include 100
µ
g Pb/ft
on floor
2
surfaces, 400
in window wells.
USEPA has proposed changing the guidance value for floor dust to 50
µ
g Pb/ft
on window sills, and 800
µ
g Pb/ft
2
2
µ
g
Pb/ft
. Samples are collected in a systematic fashion using a wet wipe on
one square foot of floor surface and a measured area (equivalent to 1 ft
2
) of
window sills and wells. Wet wipe samples can be analyzed in a laboratory
using atomic absorption analysis, or inductively coupled plasma or anodic
stripping voltammetry. It is good practice for lead analyses to be conducted
by a USEPA-approved laboratory. Wipe sampling appears to work relatively
well on hard surfaces, with less reliable results on carpeting.
House dust containing lead can also be sampled using vacuum methods.
Vacuum sampling has the potential for providing more accurate results on
fabric surfaces such as carpet. Vacuum methods evaluated have included
personal sampling pumps with a specially constructed surface vacuum
attachment and a large, heavy-duty, specially designed USEPA vacuum
cleaner. Concentrations in vacuum samples can be expressed on a unit sur-
face area or on a mass basis. Mass concentrations are expressed as the amount
of lead in dust per unit mass of dust collected (
2
g/g). Such concentration
expression does not assess the absolute mass of lead that may be present in
house dust.
Surface sampling for pesticides, plasticizers such as phthalic acid esters,
and PCBs is conducted using vacuum sampling procedures on horizontal
surfaces and by wipe sampling on hard horizontal and vertical surfaces.
Concentrations in the former case are expressed on a mass-to-mass basis
(ng/g,
µ
).
Post-fire PCB remediation effectiveness is typically determined from surface
wipe samples.
Surface sampling for mold can be conducted by collecting house dust or
sampling surfaces of mold-infested materials with transparent sticky tape.
In the former case, house dust samples are washed and separated into dif-
ferent fractions and then plated out on agar media to determine the number
of colonies that are produced on a unit dust weight basis. At the present time
there are no consensus guideline values to indicate the significance of cul-
turable/viable mold concentrations in surface dust samples relative to
human exposure and health effects. It is relatively common in building inves-
tigations to collect transparent cellophane tape samples of the surfaces of
mold-infested building materials to identify major genera present. Of partic-
ular concern are toxigenic fungi such as
µ
g/g) and in the latter case on a mass per unit area basis (
µ
g/m
2
Stachybotrys chartarum
and
Aspergillus
versicolor.
Mold may also be sampled qualitatively by the use of swab sam-
pling in which Q-tips or similar products are brushed across the surface of
infested areas and transferred to selected mold culture media.
Surface sampling is commonly conducted for allergens. Such sampling
is typically conducted by using vacuuming techniques to collect surface dust.
Dust samples are collected in locations where high allergen levels may be
