ASTM D6178-97

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Designation: D 6178 – 97
Standard Practice for
Estimation of Short-term Inhalation Exposure to Volatile
Organic Chemicals Emitted from Bedding Sets
This standard is issued under the fixed designation D 6178; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2 Definitions of Terms Specific to This Standard:
3.2.1 air change rate, n—the volume of outdoor air that
1.1 This practice covers the procedures for estimation of
enters the indoor environment in one hour, divided by the
short-term human inhalation exposure to volatile organic
volume of the indoor space.
chemicals (VOCs) emitted from bedding sets when a new
3.2.2 bedding set, n—an ensemble that includes a mattress
bedding set is first brought into a house.
for sleeping and a supporting box spring.
1.2 The estimated exposure is based on an estimated emis-
3.2.3 emission profile, n—a time-series of emission rates of
sion profile of VOCs from bedding sets.
one or more compounds.
1.3 The VOC emission from bedding sets, as in the case of
3.2.4 exposure scenario, n—a description of how and where
other household furnishings, usually are highest when the
an estimated exposure occurs, including (1) the location and
products are new. Procedures described in this practice also are
emission profile of the product or material that causes expo-
applicable to used bedding sets.
sure, (2) the indoor environment where the individual is
1.4 Exposure to airborne VOC emissions in a residence is
exposed to airborne emissions from the product or material,
estimated for a household member, based on location and
and (3) the location and activity patterns of the exposed
activity patterns.
individual.
1.5 The estimated exposure may be used for characteriza-
3.2.5 potential inhaled dose, n—the product of air concen-
tion of health risks that could result from short-term exposures
tration to which an individual is exposed times breathing rate
to VOC emissions.
times duration of exposure.
1.6 This standard does not purport to address all of the
3.2.5.1 Discussion—The potential inhaled dose is different
safety concerns, if any, associated with its use. It is the
from the dose actually absorbed by a target organ.
responsibility of the user of this standard to establish appro-
3.2.6 short-term exposure, n—an exposure of one week or
priate safety and health practices and determine the applica-
less in duration.
bility of regulatory limitations prior to its use.
3.2.7 volatile organic chemical, n—an organic compound
–2
2. Referenced Documents
with saturation vapor pressure greater than 10 kPa at 25°C.
2.1 ASTM Standards:
4. Summary of Practice
D 1356 Terminology Relating to Sampling and Analysis of
4.1 This practice describes procedures for estimation of
Atmospheres
inhalation exposure to VOCs emitted from new bedding sets
D 5116 Guide for Small-Scale Environmental Chamber De-
(1) . The estimation of exposure is based on the emission
terminations of Organic Emissions from Indoor Materials/
profiles for a bedding set, the environmental conditions in a
Products
residence where the bedding set is being used, and the location
D 5157 Guide for Statistical Evaluation of Indoor Air Qual-
and activity patterns of an exposed individual. Emission
ity Models
profiles are derived from environmental chamber emission
D 6177 Practice for Determining Emission Profiles of Vola-
tests 2(see Guide D 5116 and Practice D 6177).
tile Organic Chemicals Emitted from Bedding Sets
4.2 Estimation of exposure involves development of expo-
3. Terminology
sure scenarios, modeling of indoor-air concentrations, and
selection and calculation of exposure measures.
3.1 Definitions—For definitions and terms used in this
practice, refer to Terminology D 1356.
5. Significance and Use
5.1 The objective of this practice is to provide procedures
This practice is under the jurisdiction of ASTM Committee D-22 on Sampling
and Analysis of Atmospheres and is the direct responsibility of Subcommittee
D22.05 on Indoor Air.
Current edition approved Sept. 10, 1997. Published December 1997. The boldface numbers in parentheses refer to the list of references at the end of
Annual Book of ASTM Standards, Vol 11.03. the standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 6178
for estimation of human inhalation exposure to VOCs emitted 6.3.1 The two major steps in modeling are selection of a
from bedding sets. The estimated inhalation exposure can be model and provision of model input parameters.
used as an input to characterization of health risks from 6.3.2 Model Selection—Select a model that is capable of
short-term VOC exposures.
estimating indoor-air concentrations in multiple zones and
5.2 The results of exposure estimation for specific raw allows the user to specify various types of emission profiles in
materials and components, or processes used in manufacturing
addition to the indoor zones, their volumes, their interzonal
different bedding sets, can be used to compare their relative airflow rates, and zonal airflow rates to and from the outdoors.
impacts on exposures.
Three models that are known to meet these criteria are
CONTAM (4), EXPOSURE (5), and MCCEM (6). All three
6. Procedures for Exposure Estimation
models have been developed by or for U.S. government
6.1 The procedures for exposure estimation include devel-
agencies, and are therefore in the public domain. Each model
opment of exposure scenarios, modeling of indoor-air concen-
has advantages and disadvantages in terms of completeness,
trations, selection and calculation of exposure measures, and
simulation capabilities, the user interface, and how it addresses
model evaluation.
exposure. For example, CONTAM has the capability of calcu-
6.2 Development of Exposure Scenarios:
lating airflows among zones whereas for EXPOSURE and
6.2.1 An exposure scenario describes how and where expo-
MCCEM, the airflows need to be specified by the user;
sure occurs. In specifying the exposure scenario(s), include a
MCCEM includes a library of airflow rates for selected
description of (1) the emitting product or material, in terms of
residences.
its age, emission profile, and location, (2) the indoor environ-
6.3.3 Model Inputs—In addition to emission profiles, indoor
ment where exposure occurs, and (3) the location and activity
zones, and location and activity patterns as previously de-
patterns of an exposed individual.
scribed, specify (1) an air change rate for the residence, (2)
6.2.2 Emitting Product or Material—For this practice, the
airflow rates among the indoor zones, and (3) parameters
emitting product is a bedding set. Specify the assumed age,
related to indoor sinks. Some models may also require or allow
emission profile, indoor location, and size of the bedding set of
the user to choose a time step.
interest.
6.3.3.1 Select a value for the air change rate for the
6.2.2.1 For a conservative estimate of exposure, assume that
residence to be modeled. The air change rate for the residence
–1
the bedding set has just been purchased and the wrapper is not
with the outdoors has units of inverse hours (h ). A measured
removed until it is placed in the residence.
value for the residence representing the conditions to be
6.2.2.2 Estimate the emission profile using adjusted cham-
modeled, if available, should be used as a first choice. An
ber air concentrations (Practice D 6177).
alternative is to select a value based on appropriate cases in the
6.2.2.3 The indoor location for the bedding set is assumed to
literature. For example, a conservative value in the range from
–1
be a bedroom.
0.1 to 0.2 h and a central value in the range from 0.4 to 0.6
–1
6.2.2.4 Select a size of bedding set that is appropriate for the
h were reported by Koontz and Rector (7) based on an
size of the bedroom.
analysis of measurements from several residential field studies.
6.2.3 Indoor Environment:
Representative values for the residential building stock are not
6.2.3.1 Conceptualize the indoor environment as consisting
available.
of the following three zones: (1) the immediate vicinity of the
6.3.3.2 Multiply the air change rate by the zonal volume to
3 –1
bedding set; (2) the remainder of the bedroom in which the
obtain the airflow rate to and from the outdoors, in m h . The
bedding set is located; and (3) the remainder of the house.
simplifying assumption can be made that each zone has a
Specify a volume for the entire residence and for each of the
balanced inflow and outflow with respect to outdoors. While
zones. For a typical volume of the total residence, use the
this is generally not the case in a real building, one must have
average value (369 m ) listed in the Exposure Factors Hand-
measured interzonal airflow rates or rates that were calculated
book (3). For a conservative value of the residential volume,
with a multi-zone airflow model (such as CONTAM) to avoid
3 3
use one of the 10th percentile values (147 m or 167 m ) listed
using this assumption.
in the Exposure Factors Handbook. See X1.1 for example
6.3.3.3 Use measured values, if available, for interzonal
calculations to determine the volumes for the bedroom and the
airflow rates between the bedroom and the remainder of the
vicinity of the bedding set.
house. Alternatively, interzonal flows can be estimated using
6.2.3.2 To simplify calculations, the indoor environment can
the CONTAM model (or some other multizone airflow model)
be considered as consisting of just two zones, the bedroom and
or an equation such as the following:
the remainder of the house. Such calculations would result in
Q 5 V 0.078 1 0.31N (1)
~ !
less realistic yet useful estimates for screening purposes.
6.2.4 Location and Activity Patterns—Specify the locations
of an exposed individual throughout a 24-h (or longer) period
where:
3 –1
in relation to the two or three indoor zones previously
Q = interzonal flow rate, m h
described . Also specify the time spent outside the house, V = volume of the house, m , and
–1
during which the individual is assumed not to be exposed to N = air change rate of the house, h .
chemical emissions from the bedding set. See X1.2 for The above empirical equation is based on an analysis of flow
examples of location and activity patterns. rates from several hundred nonrandomly selected residences
6.3 Modeling of Indoor-air Concentrations: (7).
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 6178
6.3.3.4 If three zones are elected for calculations, the indoor air concentrations for the purposes of exposure estima-
bedroom area in the vicinity of the bedding set is assumed to tion should be evaluated with concentration measurements
exchange air only with the rest of the bedroom. See X1.3 for from actual residences. Use tools described in Guide D 5157 to
example calculations to determine the airflow rate between the judge the comparability of predicted and measured concentra-
vicinity of the bedroom set and the remainder of the bedroom. tions.
6.3.3.5 For a conservative approach, assume no indoor
7. Report
sinks. If indoor sinks are present, they are likely to be
reversible. Both CONTAM and EXPOSURE are capable of
7.1 The report on estimation of inhalation exposure should
handling reversible sinks. The MCCEM allows only a one-way
contain the sections listed as follows:
–1
sink, expressed as a first-order rate constant in units of h .
7.2 Bedding Set Samples—Give description of the bedding
6.3.3.6 If the model requires or allows user input for the
sets (for example, size, style), sample selection process (for
time step, then specify a time step of no longer than 15 min,
example, random), and brand name (if appropriate).
and preferably as short as 5 min or 1 min. A shorter time step
7.3 Emission Profiles—List the time-varying emissions, or
will result in longer execution time but will increase the
provide an equation describing the time-varying emissions, for
resolution of the results.
each chemical emitted from a bedding set. Describe the
6.4 Selection and Calculation of Exposure Measures:
chamber conditions and the technique used for estimating
6.4.1 Two commonly used measures of exposure are the
emissions from the chamber data.
potential inhaled dose and the maximum indoor concentration
7.4 Exposure Scenarios—Describe all assumptions used in
to which an individual is exposed.
estimating exposures, including the age and indoor location of
6.4.2 Potential Inhaled Dose—The potential inhaled dose is
the bedding set, the emission profile, the volume and partition-
the product of indoor-air concentration times breathing rate
ing of the indoor environment, the air change rate, interzonal
times duration of exposure. This dose needs to be calculated
airflows, and human location and activity patterns, and asso-
separately for each contiguous period of time when the
ciated breathing rates.
exposed individual is in a different zone of the indoor envi-
7.5 Modeling of Indoor-Concentrations—Describe model
ronment; the resultant estimates are then summed to determine
selection. List all inputs including the number of zones, air
the total inhaled dose. The time period over which the total
change rates, interzonal airflow rates, zonal volumes, and the
inhaled dose is determined could be 1 h, 8 h, or 24 h, or longer,
time step used in modeling. Include the comparison of pre-
depending on the health end point of potential concern.
dicted and measured concentrations, if available.
6.4.3 Maximum Indoor Concentration—The maximum in-
7.6 Exposure Estimates—Describe the exposure measures
door concentration to which an individual is exposed typically
selected, the manner in which each exposure measure was
is integrated over a relatively short time period such as1hor
calculated, and the resultant exposure estimates.
8 h, depending on the reference value against which the
time-integrated concentration will be compared. In determin-
8. Keywords
ing this maximum concentration, it is necessary to track the
exposed individual’s location within the indoor environment, 8.1 activity pattern; air change rate; bedding set; emission
integrating across contiguous time periods in each zone as profile; emissions; en
...