Breathing Zone Exposure Assessment - Aerosols: Measurement, Dosimetry, and Health Effects - page 39

TABLE 2.2
Advantages and Disadvantages of the BZ Approach

Active Sampling
Approaches Advantage Disadvantage Relevant Citations

BZ “Gold standard”; truest

representation of inhalation

Likely to be the most burdensome Cohen et al. (1984),

Rodes et al. (2010),
Delino et al. (2008),
Williams et al. (2003)

Waist pack Removes inlet burden from

lapel location; eliminates
need for shoulder strap

At least 0.5 m from BZ; potentially
biased by “ground cloud” for
coarse particles

Pellizzari et al. (1999)

Backpack Integral straps easy to wear

and train participant

At least 0.5 m from BZ unless lapel
inlet used; potentially biased by
“ground cloud” for coarse
particles

Rodes and Wiener (2001),
Eisner et al. (2002),
Choi et al. (2008)

Pull cart Pull cart handle Pull cart platform Evans et al. (2000)

Surrogate person No physical burden Minimal personal cloud

representativeness; constant
presence of surrogate person

Stevens et al. (2003)

Predictive
exposure models

No ield monitoring required;
low cost; validated for
predicting the IQR

Models to predict the most exposed
not yet developed or validated

Burke et al. (2001),
Ott et al. (2000)

should utilize BZ sampling approaches to allow the greatest lexibility in utilizing existing data-
bases and models. Only limited bias data are available to deine the representativeness that more
distant estimates of BZ exposures provide.
Personal exposure assessments can place an excessive burden upon study participants if the
technology is not suficiently miniaturized. Minimal participant burdens are strongly encouraged
by governmental and private institutional review boards (IRBs) in dealing with human subjects in
nonoccupational settings (e.g., NIH, 2003). Speciically, obtaining BZs can be the most burden-
some approach to assessing personal exposures, but alternative approaches are available when this
becomes an issue. Miniaturized PEMs typically have low collection rates, and often poor sensitivi-
ties (minimum detection limits) that counterproductively may limit the comparability of the data
with more robust, ixed-location technologies. Detection limit compromises will be required if suf-
iciently low-burden personal monitors are simply not available.

2.3.3 M onitoring c oMProMises
A number of strategies have been utilized to minimize the burden of conducting personal exposure
assessments. In most scenarios, only the inlet system is placed in the BZ, with the pump located
at the waist or in a backpack. The inlet can be clipped to the lapel, attached to special tabs on a
vest, or attached to a shoulder strap adjacent to the lapel. Examples are shown in Figure 2.2. The
swinging mass of a heavy inlet system can be annoying, and may affect the long-term comfort of
the participant. This type of burden may result in two undesirable occurrences: (a) early dropout
from the study (nonoccupational only) and/or (b) not wearing the sampler at all times. Moving the
inlet away from the BZ can reduce the perceived burden, but at the potential expense of reduced
representativeness to BZ. Such relocations were reported by Pellizzari et al. (1999) to have resulted
in acceptable biases for ine particles (PM 2.5 ). This would suggest that personal monitors for gas
phase contaminates (e.g., passive badges) could similarly be relocated with minimal bias. Burden