Incidence of polybrominated diphenyl ethers in central air conditioner filter dust from a new office building.
ABSTRACT This study examined polybrominated diphenyl ethers (PBDEs) in central air conditioner filter (CACF) dust from a new office building in Shenzhen, China. Human exposure to PBDE via dust inhalation and ingestion were also estimated. PBDEs level in CACF dust was lower than those in the other countries and regions. Approximately 0.671 pg/kg bw/day PM(2.5) (Particulate Matter up to 2.5 μm in size) bounded Σ(15)PBDEs can be inhaled deep into the lungs and 4.123 pg/kg bw/day PM(10) (Particulate Matter up to 10 μm in size) bounded Σ(15)PBDEs tend to be deposited in the upper parts of the respiratory system. The average total intake of Σ(15)PBDEs via dust inhalation and ingestion for adults reached ∼ 141 pg/kg bw/day in this building. This value was far below the reference dose (RfD) recommended by United States Environmental Protection Agency. Human exposure to PBDEs via dust inhalation and ingestion in the new building is less than the old ones.
Incidence of polybrominated diphenyl ethers in central air conditioner
filter dust from a new office building
Hong-Gang Nia, Shan-Ping Caoa, Wen-Jing Changa, Hui Zenga,b,*
aShenzhen Key Laboratory of Circular Economy, Shenzhen Graduate School, Peking University, Shenzhen 518055, China
bDepartment of Ecology, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
a r t i c l e i n f o
Received 25 September 2010
Received in revised form
23 November 2010
Accepted 9 December 2010
Polybrominated diphenyl ethers
Central air conditioner filter
New office building
a b s t r a c t
This study examined polybrominated diphenyl ethers (PBDEs) in central air conditioner filter (CACF) dust
from a new office building in Shenzhen, China. Human exposure to PBDE via dust inhalation and ingestion
were also estimated. PBDEs level in CACF dust was lower than those in the other countries and regions.
Approximately 0.671 pg/kg bw/day PM2.5(Particulate Matter up to 2.5 mm in size) bounded S15PBDEs can
be inhaled deep into the lungs and 4.123 pg/kg bw/day PM10(Particulate Matter up to 10 mm in size)
bounded S15PBDEs tend to be deposited in the upper parts of the respiratory system. The average total
intake of S15PBDEs via dust inhalation and ingestion foradults reached ∼141 pg/kg bw/day in this building.
This value was far below the reference dose (RfD) recommended by United States Environmental
Protection Agency. Human exposure to PBDEs via dust inhalation and ingestion in the new building is less
than the old ones.
? 2010 Elsevier Ltd. All rights reserved.
Polybrominated diphenyl ethers (PBDEs) are a class of flame
retardant chemicals added to many consumer products. These
in house dust over time (Betts, 2008; Harrad et al., 2010). Because
consumers usually keep PBDE-containing products for years,
many indoor spaces continue to have potential sources of PBDEs
exposureisnotfromfood,butrather fromindoordust. Therefore,to
study PBDEs in indoor environment and their implications for
human exposure is necessary. Although many previous studies
concerned indoor air or dusts and human health implications of
PBDEs, they were seldom focused on central air conditioner filter
(CACF) dusts (Abdallah et al., 2008; Harrad et al., 2008b; Stapleton
et al., 2006; Staszowska et al., 2008; Suzuki et al., 2009; Wilford
et al., 2005; Zhu et al., 2007a,b). The CACF dust is able to cover the
essential information of PBDEs in indoor environments in a given
time interval. Moreover, central air conditioner systems have been
widely used in many publics such as supermarket, library, office,
airplane cabin and so on. Therefore, studying of PBDEs in CACF dust
is useful to better understand the occurrences and health implica-
tions of PBDEs in indoor environments.
Shenzhen is situated in the subtropical part of China, as its
characteristic climatic conditions, such as long duration of hot
weather season with high temperature and humidity, warrant the
extended use of air conditioning in office buildings. Generally, the
air conditioner is in use for eight months at least from April to
November eachyear. As a result, human exposure to PBDEs through
inhalation and dermal contact may be an important route for
human accumulation of PBDEs.
A new office building was selected as a sampling site to ensure
the PBDE loadings in the samples were reflective of recent emission
sources. This study has presented a comprehensive dataset doc-
umenting the CACF-related human exposure to PBDEs, and should
provide a solid start for more investigations into the importance of
CACFs in inducing human health risk concerns.
2.1. Sample collection
We collected 56 CACF dust samples in March 2009. These CACFs were cleaned
only once during 2008e2009. Therefore, the CACF dust samples were accumulated
for oneyear and theycan reflect theyearly PBDEs pollution in indoor air. At the same
time, six personal computer (PC) dust samples were also randomly collected from
these offices. The CACF dust samples were swept with a clean brush from the CACF.
PC dust samples were collected from the back cabinets of the computers. Both CACF
and PC dusts were sweptonto aluminum foil and then sealed inpolyethylene zip bag
* Corresponding author.
E-mail address: email@example.com (H. Zeng).
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Environmental Pollution 159 (2011) 1957e1962
after removing the possible debris other than dusts. The dust samples were trans-
ported to laboratory where they were refrigerated at ∼4?C until further processing.
2.2. Analytical procedure
The dust samples spiked with13C-BDE15,13C-BDE77, and13C-BDE209 as surro-
gate standards prior to Soxhlet extraction with a 1:1 (v:v) acetone/hexane mixture
for 24 h. The extract was concentrated to ∼1 mL with a Rotary Evaporator, solvent
exchanged to hexane, and further concentrated to ∼1 mL. The concentrated extract
was purified on a glass column (10 mm i.d.) packed with, from the bottom to top,
neutral alumina (6 cm, 3% deactivated), neutral silica gel (2 cm, 3% deactivated), 25%
sodium hydroxide silica (5 cm), neutral silica gel (2 cm, 3% deactivated), 44% sulfuric
acid silica (6 cm), and anhydrous sodium sulfate (2 cm). The fraction containing
PBDEs was eluted on this glass column first with 30 mL of hexane and then 60 mL of
hexane:dichloromethane (1:1 in volume), and the eluant was concentrated
to ∼0.5 mL and further reduced to100 mL under a gentle nitrogen stream. An internal
standard,13C-PCB-208, was added to the final extract prior to instrumental analysis.
All sample extracts were analyzed with an Agilent 7890A gas chromatography
equipped with mass selective detector with a splitless injection. The ionization
mode is electron impact and the type of mass spectrometry used is quadrupole rods
tandem mass spectrometry. Ultrahigh purity helium was used as carrier with a flow
rate of 1 mL/min. Chromatographic separation was obtained with a DB-5MS
(15 m ? 0.25 mm i.d. with 0.10 mm film thickness) capillary column. The oven
temperaturewas initiallyset at 100?C, and then ramped to300?C at 8?C/minwhere
it was held for 15 min. The injector and detector temperatures were maintained at
250?C. Concentrations were determined using the internal calibration technique.
Fifteen target compounds (including BDE28, 47, 49, 85, 99, 100, 153, 154, 138, 183,
196, 206, 207, 208, and 209) and their molecular ions used for quantitation are listed
in Table S1 (“S” indicates tables and figures presented in the Supplementary data
A Mastersizer-2000 particle size analyzer (Malvern Instruments Ltd, Worces-
tershire, UK) with a wet module (Hydro 2000) was used to determine the size
distribution and mean particle size of the CACF dust. The dust samples were diluted
with deionized water to be in the obscuration range of 11e14% as recommended by
2.3. Quality control
Procedural, spiked blanks and matrix spiked samples (15 PBDE congeners
spiked into pre-extracted dust samples) were processed with each batch of 10 dust
samples. The recoveries of the surrogate standards in all samples were 78 ? 19%
for13C-BDE15 and 76 ? 15% for13C-BDE77.13C-BDE209 was also used as a surro-
gate standard initially; however, it was not possible to obtain accurate quantitative
data because the instrument response of
13C-BDE209 was deemed as an inappropriate surrogate standard for the analysis of
dust samples with the present instrumental method, and it was excluded entirely
from the list of surrogate standards (detailed in Supplementary data). The recov-
eries of all BDE congeners ranged from 63 to 109% with a standard deviation (SD)
of <18% in six spiked matrix samples, and from 59 to 111% with an SD of <14% in
six spiked blanks. BDE209, BDE100, and BDE47 at levels close to or only slightly
higher than the lowest concentrations of the calibration curves were found in
approximately 10% the procedural blank samples; their average values were not
deducted from the measured concentrations in the dust samples. The nominal
reporting limit, defined as the lowest concentration level from the calibration
curve for a specific analyte divided by the actual sample size, for 15 PBDEs were
given in Table S1.
13C-BDE209 was poor. As a result,
2.4. Data analysis
2.4.1. Indoor dust concentrations
The central air conditioner system conditions the indoor air by removing dust
and dirt when the air is recycling in office after cooling. Reinforce of fresh air to the
air circulation is seldom conducted and can be negligible, according to the worker of
property management company. As mentioned in introduction section, the CACF
dusts are mainly come from the suspended particles in indoor air. Therefore, the key
assumption that the dusts captured onto the CACF represent the dusts in the indoor
air is reasonable. The CACF dusts were accumulated in one year because the CACF
were cleaned only once during 2008e2009. On the basis of these considerations,
annually average concentrations of dusts in the office air, Cdust(g/m3) can be esti-
mated approximately as:
Cdust¼ k ? r ? Mdust=ðL ? W ? H ? 365Þ
where, k ¼ unit conversion factor, r ¼ relative volume fraction of dust within a given
particle size range, Mdust¼ mass of CACF dust sample (g), L ¼ length of the office (m),
W ¼ width of the office (m), H ¼ height of the office (m) (Fig. 1). The calculated
results were summarized in Table S2. This calculation performed with four key
assumptions include (1) reinforce air can be negligible, (2) settled dust is cleaned
frequently and no contribution to indoor air, (3) dust is evenly distributed on each
day throughout one year, (4) dust density is uniform for all size particles. Obviously,
these estimates were approximate.
Fig. 1. Abridged general view of the office studied and the air flow of the central air conditioner system.
H.-G. Ni et al. / Environmental Pollution 159 (2011) 1957e1962
2.4.2. Particle-size distribution of PBDEs
Obviously, PBDEs will not distribute uniformly in different particle-size frac-
tions. In reality, PBDE particle-size distribution featured a distinct enrichment in
smaller particles (Deng et al., 2007; Mandalakis et al., 2009). The particle-size
distributions of PBDEs were predicted as procedure detailed below. Firstly, dust was
defined as three size categories depending on their particle size, PM10(Particulate
Matter up to 10 mm in size), PM2.5(Particulate Matter up to 2.5 mm in size) (United
States Environmental Protection Agency, 2010) and larger dusts (LD) whose size is
larger than 10 mm. In the present study, dusts which size between 0.4 and 2.2 mm
(r ¼ 6%, Fig. S1) and between 2.5 and 8.9 mm (r ¼ 24%, Fig. S1) were subsumed in
PM2.5and PM10, respectively. The relative volume fraction of LD was w70% (Table S3
and Fig. S1). Secondly, PBDEs in CACF dusts were allocated to PM10, PM2.5, and LD
according to the relative volume fraction of dust and proportions of particle-size
distribution of PBDEs (the calculation procedure detailed in the Supplementary
2.4.3. Human exposure model
Based on the measurements of PBDEs concentration in CACF dust, occupational
exposures to PBDEs in CACF dust were estimated. The exposure pathways of interest
are dust inhalation and oral ingestion.
As discussed in Sections 2.4.1 and 2.4.2, we calculated the PBDEs average
concentrations in the suspended particles with different size indoor air. And then
the exposure via particles inhalation, E (pg/kg bw/day), can be estimated as
E ¼ CPM? IR ? t=bw
where CPM(pg/m3) is PBDEs concentration in PM, IR is inhalation rate (m3/d), t is
exposure time (h), and bw is the body weight of the exposure person (kg). With
IR ¼ 13 m3/d, bw ¼ 70 kg (Chen et al., 2010 and references therein), t ¼ 8 h, and the
CPMlisted in Table 1, the PM inhalation exposure was estimated and listed in Table 1.
Generally, the smaller the particle, the stronger its potential impact on human
health. For this reason, U.S. Environmental Protection Agency monitors and regu-
lates particles in two size categories (PM10and PM2.5) depending on their predicted
penetration into the lungs.
3. Results and discussion
3.1. PBDEs in CACF dust
Table 2 summarized the concentrations of PBDEs in both CACF
dust and PC dust. Of the 56 CACF dust samples analyzed, the
median and mean concentration of S15PBDEs (sum of all target BDE
congeners including BDE209) were 477 ng/g and 920 ng/g,
respectively. S15PBDEs concentrations in CACF dust varied widely
ranging from 39 ng/g to15,914 ng/g (Table 2). This can be attributed
to different indoor characteristics among offices. As documented,
the number and brands of PBDE-containing consumer products
(such as computers, chairs, and furniture), the time of using
computer, and the air exchange rates were not similar for offices.
No published data on PBDEs concentrations in CACF dust are
availableforcomparisonupto now.However, increasingnumbers of
studies on indoor dust have been carried out. The comparison with
these studies will also be given some useful information. In general,
PBDEs levels in CACF in the present study were lower than that in
settled dust in the other countries (especially in USA) (Batterman
et al., 2009). As seen in Fig. S2, the PBDE levels found in this study
(mean 920 ng/g) were lower than those in Haikou (mean 1873 ng/g)
and Guangzhou (mean 3407 ng/g) of China (Huang et al., 2010),
Birmingham, UK (Harrad et al., 2008a), Washington DC, USA (mean
5900 ng/g) (Stapleton et al., 2005), Singapore (2900 ng/g) (Tan et al.,
2007), New York, USA (mean 3190 ng/g) (Johnson-Restrepo and
Kannan, 2009), and Ottawa, Canada (mean 5500 ng/g) (Wilford
et al., 2005), but was comparable to that in Wuhan (810 ng/g),
world (Fig. S2). Moreover, PBDEslevelsin some kind of environment
media from China were lower than those in other countries (Huang
et al., 2010; Mai et al., 2005; Meng et al., 2007a,b). This suggested
more commercial PBDE formulations were consumed in North
America than that in Asia in history (Huang et al., 2010; Meng et al.,
2007a). But this is not the only explanation for the lower levels of
PBDE in CACF dust from a six-year-old office building (2003e2009).
Obviously, there are no historical cumulative effects of PBDE pollu-
tion because the sampling offices are all new. So, the most possible
explanation is “fresh pollution”, which means PBDEs in CACF were
cumulated in a short duration by fresh emissions from indoor PBDE-
containing materials. Considering the study sites are far from the
other possible PBDEs sources (there are no any enterprises and
industries around), the major sources have to be the indoor
consumer products. Meanwhile, PBDEs were detected in such a new
office building indicate that indoor PBDE pollution will not reduce
unless PBDEs were disused entirely.
Particle-size distribution of PBDEs in the office air and estimated exposures to PBDEs via dust inhalation and ingestion.
Exposure via dust inhalation (pg/kg bw/day)
Exposure via dust ingestion (pg/kg bw/day)b
0.2600.1410.329 0.1700.531 0.042 0.2090.0450.1061.251 9.5445.8842.883 88.30131.0
aSum of exposure via dust ( including PM10and PM2.5) inhalation.
bExposure estimation via dust ingestion.
H.-G. Ni et al. / Environmental Pollution 159 (2011) 1957e1962
3.2. Congeners profiles in CACF dust and PC dust
In dust samples (CACF dust and PC dust), BDE206, 207, and 208
were dominant (with a contribution order of BDE209 > B-
DE206 > BDE207 > BDE208) (Table 2 and Fig. 2). They were in line
with the congener profiles of the commercial decaBDE mixture
from Europe, USA, and China (Fig. S3) (Chen et al., 2010; La Guardia
et al., 2006; Luo et al., 2009). Beside that, high concentration of
BDE47, BDE100, and BDE99 was also found. This did not agree with
the results obtained by Batterman et al. (2009) that high BDE206
and BDE209 were observed occasionally. A reasonable explanation
is the flame retardants used in the current office furniture mainly
are high-brominated BDEs.
Congener profiles of PBDEs in CACF dust and PC dust were
similar (Fig. 2). BDE209 was the predominant congener in both
CACF and PC dust samples, contributing 80.4% and 77% to the CACF
dust and PC dust, respectively. A very good correlation between
PBDEs in CACF dusts and PC dusts was also observed (insert picture
in Fig. 2). PBDEs could equilibrate between the CACF and computer
dusts, thus compromising any difference in compositions that
might have been present initially. Therefore, this correlation just
showed computers seem to be contributed to PBDE in CACF dust.
In the CACF dust, decaBDE mixture (BDE206, 207 208, and 209)
contributes 76e97%, while pentaBDE (BDE28, 47, 99, 100, 153, and
154) contributes only 0.1%e10%.
The deca-congener profile (for PC dust and CACF dust) matched
upwellwith the commercial mixture(Fig. S3). This reconfirmed the
conclusion that decaBDE is quite predominant in commercial
mixture in China (Chen et al., 2010). It is notable that BDE209 can be
debrominated to lower brominated congeners, for example pen-
taBDE e.g., photodecomposition in air (Kajiwara et al., 2008;
Söderström et al., 2004). So, we believe low relative abundance
pentaBDE in CACF dust partlyoriginated from the debromination of
decaBDE. Despite that mentioned above, to claim that pentaBDE is
not being produced and adding in consumer products is still lacking
direct evidences so far, although a certain study supposes that
pentaBDE’s usage has been phased out in China (Chen et al., 2010).
It was said pentaBDE is being produced in China and may enter
North America in furniture from China (Betts, 2008). Therefore,
whether pentaBDE is being produced and used in China need
3.3. Human exposure to PBDEs in CACF dust
In the present study, we estimated the PM inhalation exposure
according to the two size categories (Table 1 and Fig. 3). As is
showing by Fig. 3, average 0.671 pg/kg bw/day (range, 0.018e1.526)
PM2.5 bounded S15PBDEs can be inhaled deep into the lungs,
reaching the pulmonary alveoli (Fig. 3). They can cause breathing
and respiratory problems. At the same time, average 4.123 pg/
kg bw/day (range, 0.110e8.890) PM10bounded S15PBDEs tend to be
depositedin theupperpartsof therespiratorysystem (Fig.3).These
particles can generally be expelled back into the throat and there-
fore do less harm to human health than PM2.5. The total PM
(PM2.5þ PM10) bounded S15PBDEs maximum exposure reached
10.41 pg/kg bw/day. No published data on exposure to PM (PM2.5or
PM10) bounded PBDE can be used to compare with. However,
general inhalation exposure to indoor air or dust can be conducted.
Chen et al. (2010) obtained the exposure of PBDEs from household
products via inhalation (175 pg/kg bw/day) is nearly 17 times as our
estimation (maximum data of 10.41 pg/kg bw/day). This difference
suggested that human exposure to PBDEs from household products
in new buildings is far less than that from old ones. However, no
PBDEs concentrations (ng/g) in air conditioning filter dust and personal computer dust.
Compounds Central air conditioner filter dust Computer dust
Min ¼ minimum, max ¼ maximum, DF ¼ detection frequency (%).
) g / g
o i t a r t n
Fig. 2. Comparison of PBDE concentrations in central air conditioner filter (CACF) dust
and personal computer (PC) dust. Correlation of PBDE congeners in CACF dust and PC
dust is showing by the insert picture.
H.-G. Ni et al. / Environmental Pollution 159 (2011) 1957e1962
to PBDEs in the volatile fraction should be minor due to highly
brominated congeners dominated (Table 1).
It is generallyconsidered that settled dust exposure is presumed
to occur via ingestion while suspended dust occurs via inhalation.
When we assumed that concentrations of PBDE in CACF dust have
the same values as in settled dust, the exposure via dust ingestion
also can be estimated. With 10 mg/d ingestion rate (Gevao et al.,
2006 and references therein) for an adult and the average
concentrations were used to estimate exposure via dust ingestion.
As seen in Table 1, the average exposure to PBDE via dust ingestion
will reach ∼131 pg/kg bw/day. Clearly, unintentional dust ingestion
takes more PBDEs than inhalation (10.41 pg/kg bw/day).
United States Environmental Protection Agency recommends
the reference dose (RfD) of daily oral PBDE exposure. The RfD was
0.1, 0.1, 0.2, and 7 mg/kg bw/day for BDE47, 99,153, and 209 (Staskal
et al., 2008). Clearly, the average total intake of PBDEs via inhalation
and ingestion (∼141 pg/kg bw/day) for adults in offices was far
below the RfD recommended values. This is because no influence of
historical PBDE pollution in this new office building. However,
considering the large quantities of PBDE-containing products are
still in use in China and PBDEs will emit from indoor consumer
products to the indoor environments, further studies are needed to
fully understand the emission mechanism of PBDE from indoor
This study presents the investigation on incidences of PBDE in
dust captured on CACF in the duration of one year. Without
historical cumulative pollution and contribution of point source,
the results can be regarded as the demonstration of PBDE pollution
in indoor environments in more recent years. The estimates of
human exposure to PBDE via inhalation and ingestion may be
useful to understand the human health implications in other
microenvironments (such as commercial building, aircraft carbine,
vehicle interiors, and other public space) where the central air
conditioner systems were equipped with. PBDE emissions from
indoor sources can be expected to continue for a long time as
the PBDE-containing products in offices were to be kept many
years. Unfortunately, it is not entirely clear how PBDE (especially
decaBDE) is released from products, though some think that it
might be released from physical abrasion or deterioration of the
product. Further study on real migration mechanism of PBDE from
consumer products to air and dust is distinctly important. Addi-
tionally, the distribution of PBDEs in particulate matter with
different size has not been fully characterized, particularly for the
decaBDE commercial product, which should partition differently
from lower brominated PBDEs.
Needing what do not explain especially is that collection effi-
ciency and greater spatial coverage are very indispensable for this
sort of research. The CACFs were not changed according to the
recommended schedule. This would result in changes in their
particle collection efficiency and air flow over time. Occupancy of
the building may affect the concentration of suspended particles.
The programmed thermostats used in the building might alter air
concentrations during a 24 h cycle. All mentioned here will affect
sampling efficiency. This is also the inadequacy of the present study
needing to remedy in our further work.
This research was financially supported by the National Natural
Science Foundation of China (No. 41071303, 40830747) and the
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