Screening Indoor Plants for Volatile Organic Pollutant Removal Efficiency

Abstract

Twenty-eight ornamental species commonly used for interior plantscapes were screened for their ability to remove five volatile indoor pollutants: aromatic hydrocarbons (benzene and toluene), aliphatic hydrocarbon (octane), halogenated hydrocarbon [trichloroethylene (TCE)], and terpene (-pinene). Individual plants were placed in 10.5-L gas-tight glass jars and exposed to 10 ppm (31.9, 53.7, 37.7, 46.7, and 55.7 mg·m –3) of benzene, TCE, toluene, octane, and -pinene, respectively. Air samples (1.0 mL) within the glass containers were analyzed by gas chromatography–mass spectroscopy 3 and 6 h after exposure to the test pollutants to determine removal efficiency by monitoring the decline in concentration over 6 h within sealed glass containers. To determine removal by the plant, removal by other means (glass, plant pot, media) was subtracted. The removal efficiency, expressed on a leaf area basis for each volatile organic compound (VOC), varied with plant species. Of the 28 species tested, Hemigraphis alternata, Hedera helix, Hoya carnosa, and Asparagus densiflorus had the highest removal efficiencies for all pollutants; Tradescantia pallida displayed superior removal efficiency for four of the five VOCs (i.e., benzene, toluene, TCE, and -pinene). The five species ranged in their removal efficiency from 26.08 to 44.04 µg·m–3·m–2·h–1 of the total VOCs. Fittonia argyroneura effectively removed benzene, toluene, and TCE. Ficus benjamina effectively removed octane and -pinene, whereas Polyscias fruticosa effectively removed octane. The variation in removal efficiency among species indicates that for maximum improvement of indoor air quality, multiple species are needed. The number and type of plants should be tailored to the type of VOCs present and their rates of emanation at each specific indoor location.

Full text

HORTSCIENCE 44(5):1377–1381. 2009.
Screening Indoor Plants for Volatile
Organic Pollutant Removal Efficiency
Dong Sik Yang
Department of Horticulture, University of Georgia, Athens, GA 30602-7273
Svoboda V. Pennisi
Department of Horticulture, University of Georgia, Griffin, GA 30223
Ki-Cheol Son
Department of Environmental Science, Konkuk University, Seoul 143-701,
Korea
Stanley J. Kays
1
The Plant Center, Department of Horticulture, University of Georgia, 1111
Plant Science Building, Athens, GA 30602-7273
Additional index words. volatile organic compounds, benzene, toluene, octane, trichloroeth-
ylene, a-pinene, phytoremediation, indoor air quality
Abstract. Twenty-eight ornamental species commonly used for interior plantscapes were
screened for their ability to remove five volatile indoor pollutants: aromatic hydro-
carbons (benzene and toluene), aliphatic hydrocarbon (octane), halogenated hydrocar-
bon [trichloroethylene (TCE)], and terpene (a-pinene). Individual plants were placed
in 10.5-L gas-tight glass jars and exposed to ’
’10 ppm (31.9, 53.7, 37.7, 46.7, and
55.7 mgm
–3
) of benzene, TCE, toluene, octane, and a-pinene, respectively. Air samples
(1.0 mL) within the glass containers were analyzed by gas chromatography–mass
spectroscopy 3 and 6 h after exposure to the test pollutants to determine removal
efficiency by monitoring the decline in concentration over 6 h within sealed glass
containers. To determine removal by the plant, removal by other means (glass, plant pot,
media) was subtracted. The removal efficiency, expressed on a leaf area basis for each
volatile organic compound (VOC), varied with plant species. Of the 28 species tested,
Hemigraphis alternata,Hedera helix,Hoya carnosa, and Asparagus densiflorus had the
highest removal efficiencies for all pollutants; Tradescantia pallida displayed superior
removal efficiency for four of the five VOCs (i.e., benzene, toluene, TCE, and a-pinene).
The five species ranged in their removal efficiency from 26.08 to 44.04 mgm
–3
m
–2
h
–1
of
the total VOCs. Fittonia argyroneura effectively removed benzene, toluene, and TCE.
Ficus benjamina effectively removed octane and a-pinene, whereas Polyscias fruticosa
effectively removed octane. The variation in removal efficiency among species indicates
that for maximum improvement of indoor air quality, multiple species are needed. The
number and type of plants should be tailored to the type of VOCs present and their rates
of emanation at each specific indoor location.
The importance of indoor air quality to
human health has become of increasing
interest in developed countries where inhab-
itants often spend over 90% of their time
indoors (Jenkins et al., 1992; Snyder, 1990).
Indoor air has been reported to be as much as
12 times more polluted than that outdoors
(Ingrosso, 2002; Orwell et al., 2004; Zabiega1a,
2006). Indoor air pollutants primarily origi-
nate from building product emissions, human
activities inside the building, and infiltration
of outdoor air (Wolkoff and Nielsen, 2001;
Zabiega1a, 2006) and have increased as a
result of the lower gas exchange rates of
newer, more energy-efficient buildings (Cohen,
1996). Indoor air pollutants include volatile
organic compounds (VOCs), particulate mat-
ter, ozone, radon, lead, and biological con-
taminants (Destaillats et al., 2008). Exposure
can cause acute illnesses (e.g., asthma,
nausea) and chronic diseases (e.g., cancer,
immunologic, neurologic, reproductive, de-
velopmental, and respiratory disorders) (Suh
et al., 2000).
VOCs emanating from paints, varnishes,
adhesives, furnishings, clothing, solvents,
building materials, combustion appliances,
and potable water (Jones, 1999; Maroni et al.,
1995; Zabiega1a, 2006) have a negative ef-
fect on indoor air quality (Darlington et al.,
2000). VOCs are generally classified as
aromatic hydrocarbons (e.g., benzene, tolu-
ene, ethylbenzene, xylene), aliphatic hydro-
carbons (e.g., hexane, heptane, octane,
decane), halogenated hydrocarbons [e.g., tri-
chloroethylene (TCE), methylene chloride],
and terpenes (e.g., a-pinene, d-limonene)
(Jones, 1999; Suh et al., 2000; Wolkoff and
Nielsen, 2001; Won et al., 2005; Zabiega1a,
2006). Benzene and toluene, octane, TCE, and
a-pinene are representative VOCs from each
class (i.e., aromatic hydrocarbons, aliphatic
hydrocarbons, halogenated hydrocarbons, and
terpenes, respectively) and are considered to
be important indoor air pollutants as a result
of their toxicity (Liu et al., 2007; Newman
et al., 1997; Orwell et al., 2006).
Plants remove VOCs from indoor air
through stomatal uptake, absorption, and
adsorption to plant surfaces (Beattie and
Seibel, 2007; Korte et al., 2000; Sandhu
et al., 2007). Several indoor species have
been screened for their ability to remove
benzene (Liu et al., 2007), some of which
could remove 40 to 88 mgm
–3
d
–1
(Orwell
et al., 2004), in addition to other VOCs (e.g.,
toluene, TCE, m-xylene, hexane) (Cornejo
et al., 1999; Orwell et al., 2006; Wood et al.,
2002; Yoo et al., 2006). The efficiency of
VOC removal varies substantially among
species (Yoo et al., 2006) and with the
molecular characteristics of each compound.
To date, only a limited number of indoor
species have been tested for their phytoreme-
diation potential and the range of pollutants
assessed is even more limited (Cornejo et al.,
1999; Ugrekhelidze et al., 1997; Wolverton
et al., 1989; Wood et al., 2002). It is evident
that a better understanding of the phytoreme-
diation potential of a diverse range of indoor
plants is needed. In this study, a cross-section
of indoor plants (28 species) was screened for
their ability to remove five important VOCs
with differing chemistries (benzene, toluene,
octane, TCE, and a-pinene).
Materials and Methods
Plant material. Twenty-eight species of
popular indoor ornamental plants available in
the southeastern United States, which repre-
sented 26 genera and 15 botanical families
(Table 1), were obtained from commercial
sources. After the media was washed from
the roots, the plants were repotted in 10-cm
(500-cc) pots using a growing media com-
prised of peatmoss, pine bark, and perlite/
vermiculite (2:1:1, v/v) (Fafard 3B; Fafard,
Anderson, SC) and grown in a shade house
for 8 weeks before acclimatization for 12
weeks under indoor conditions, 22 ± 1 C,
50% relative humidity, and 5.45 mmolm
–2
s
–1
photosynthetically active radiation (PAR)
(LI-COR LI-189 light meter with a line
quantum sensor; LI-COR, Lincoln, NE).
The plants were watered as needed during
growth and acclimatization periods. At the
end of the experiment, the leaf areas were
determined using a LI-3100c leaf area meter
(LI-COR) to allow expressing the removal
efficiency on a leaf area basis.
Introduction of volatile organic com-
pounds. Plants were placed in 10.5-L gas-tight
glass jars (one plant/jar) with the lid fitted with
welded stainless steel tubing inlet and outlet
ports. To facilitate a uniform distribution of
the gases in the jar, the inlet tubing extended
downward within the jar following the contour
of the side of the jar, three-fourths of the
distance to the base. The lids were sealed using
specially constructed 11.8 cm o.d. ·9.8 cm i.d.
Received for publication 14 Nov. 2008. Accepted
for publication 7 Jan. 2009.
1
To whom reprint requests should be addressed;
e-mail kaysstan@uga.edu.
HORTSCIENCE VOL. 44(5) AUGUST 2009 1377
POSTHARVEST BIOLOGY AND TECHNOLOGY

gaskets in which a 4.2-mm-thick EPDM rub-
ber gasket was sealed within a Teflon envelope
(Phelps Industrial Products, Elkridge, MD).
The inlet port was connected to a charcoal
filter [Pyrex glass tube (10 cm ·1 cm i.d.) with
2.5 g of charcoal (Alltech Assoc. Inc., Deer-
field, IL)] such that purified air was introduced
into the jar at 150 mlmin
–1
. The plants were
placed in the jars 24 h before treatment and
were maintained at 5.45 mmolm
–2
s
–1
PAR
during a light period (12 h). Just before the
introduction of the VOCs, the inlet and outlet
ports were closed using gas-tight Swagelok
fittings (Georgia Valve & Fitting, Co., Alphar-
etta, GA). The exit port was configured with
Swagelok fittings holding a gas-tight gas
chromatography septum that was capped to
prevent leakage. The cap was briefly removed
when a gas sample was drawn for analysis.
The individual plants were exposed to 10
ppm (31.9, 53.7, 37.7, 46.7, and 55.7 mgm
–3
)
of high-purity analytical-grade benzene, TCE,
toluene, octane, and a-pinene (Table 2),
respectively, in the gas-tight glass jars.
Through preliminary tests, concentrations of
9.66 (30.9), 11.00 (59.1), 9.66 (36.4), 9.49
(44.3), and 9.82 (54.7) ppm (mgm
–3
)ofeach
compound were created by introducing 2.0,
2.7, 2.4, 4.0, and 4.0 mL of benzene, TCE,
toluene, octane, and a-pinene, respectively,
into the jar using a microsyringe (Agilent
Technologies, Wilmington, DE) and calibrat-
ing the amount of each compound adsorbed
onto the inner surface of the jar. A small 4 cm
diameter 6-V DC brushless fan (RadioShack,
Fort Worth, TX) was placed near the top of
each jar to ensure adequate mixing of the
volatiles. The gas concentration within the jar
was determined after 3 and 6 h during the day.
Three replications of each species were tested
at a setting with a fourth jar used as a control
without the potted plant to measure the con-
centration of airborne VOCs within the empty
jar. Leak tests were carried out on the empty
jar before every fourth experiment; no leakage
was found during the 6-h test period.
Analysis of volatile organic compounds.
Air samples (1.0 mL) within the glass con-
tainers were removed during the light period
from the outlet port using a gas-tight syringe
(Agilent Technologies) 3 and 6 h after expo-
sure to the test VOCs and analyzed by
capillary gas chromatography–mass spec-
troscopy (GC-MS) (6890N/5973; Agilent,
Palo Alto, CA) equipped with a 30 m length
(0.25 mm i.d., 0.25 mm film thickness of 5%
phenyl methyl siloxane) capillary column
(HP-5MS; Agilent). The injection port tem-
perature was 225 C and was operated in the
splitless mode. Helium was used as the
carrier gas at a flow rate of 1.8 mLmin
–1
.
The column temperature was held at 36 C
for 0.5 min and then programmed at 10 C/
min to 90 C and held for 1 min. Mass
spectroscopy conditions were: ion source
230 C; electron energy 70 eV; multiplier
voltage 1247 V; GC-MS interface zone 280
C; and a scan range of 35 to 350 mass units.
For quantifying absolute concentrations of
each compound, standard curves for each
compound were determined using analytical
standards. Solutions of 0.5, 1, 2, 5, 10, 20, 50,
and 100 mLL
–1
in hexane of each compound
were prepared. Each standard solution (1.0
mL, three replications) was injected directly
into the GC-MS using a microsyringe. The
concentration of VOCs removed by a plant
was calculated as (Yoo et al., 2006):
ðAÞVOC removal efficiency
=½CðSMÞ=ðL3TÞ½1
ðBÞAccumulated removal concentration of
VOC = ½CðSMÞ=L½2
where:
C = the concentration of VOC in the
control jar (mgm
–3
)
S = the concentration of VOC in the
sample jar (mgm
–3
)
Table 1. Family, Latin binomial, common name, and leaf area of test plants exposed to five representative volatile organic compounds (benzene, toluene, octane,
trichloroethylene, and a-pinene) over 6 h during the day.
No. Family Latin binomial Common name Leaf area (cm
2
/plant)
1 Acanthaceae Fittonia argyroneura Coem. Silver-net leaf 660 ± 45
2 Acanthaceae Hemigraphis alternata (Burm.f.) T. Anders ‘Exotica’ Purple waffle 352 ± 37
3 Agavaceae Dracaena fragrans (L.) Ker-Gawl. Corn plant 712 ± 39
4 Agavaceae Sansevieria trifasciata Prain Snake plant 346 ± 51
5 Anthericaceae Chlorophytum comosum (Thunb.) Jacq. ‘Fire Flash’ Spider plant 574 ± 76
6 Araceae Anthurium andreanum Linden Flamingo flower 616 ± 76
7 Araceae Dieffenbachia seguine (Jacq.) Schott
z
Dumb cane 670 ± 52
8 Araceae Philodendron scandens ssp. oxycardium Heart leaf philodendron 1085 ± 28
9 Araceae Epipremnum aureum
y
Pothos 1201 ± 136
10 Araceae Spathiphyllum wallisii Regal Peace lily 598 ± 58
11 Araceae Syngonium podophyllum Schott Arrowhead vine 718 ± 54
12 Araliaceae Schefflera arboricola (Hayata) Merr. ‘Variegata’ Variegated schefflera 587 ± 56
13 Araliaceae Schefflera elegantissima (Hort. Veitch ex Mast.) Lowry & Frodin
x
False aralia 372 ± 68
14 Araliaceae Hedera helix L. English ivy 319 ± 20
15 Araliaceae Polyscias fruticosa (L.) Harms Ming aralia 477 ± 26
16 Asclepiadaceae Hoya carnosa (L.f.) ‘Variegata’ Variegated wax plant 452 ± 51
17 Bromeliaceae Guzmania sp. Guzmani bormeliad 535 ± 78
18 Commelinaceae Tradescantia pallida (Rose) D.R. Hunt ‘Purpurea’ Purple heart plant 253 ± 33
19 Euphorbiaceae Codiaeum variegatum (L.) Blume Croton 926 ± 48
20 Geraniaceae Pelargonium graveolens L’Her. ex Ait. Rose geranium 501 ± 79
21 Liliaceae Asparagus densiflorus (Kunth) Jessop ‘Sprengeri’ Asparagus fern 337 ± 9
22 Liliaceae Aspidistra elatior Blume ‘Milky Way’ Cast iron plant 1079 ± 192
23 Marantaceae Calathea roseopicta (Linden) Regal Peacock plant 650 ± 78
24 Marantaceae Maranta leuconeura E. Morren Prayer plant 574 ± 13
25 Moraceae Ficus benjamina L. Weeping fig 482 ± 36
26 Moraceae Ficus elastica Roxb. Rubra Red rubber tree 562 ± 34
27 Palmae Howea belmoreana (C. Moore & F. Muell.) Becc. Sentry palm 769 ± 108
28 Piperaceae Peperomia clusiifolia (Jacq.) Hook. ‘Variegata’ Variegated red-edged peperomia 935 ± 22
Data are means ± SEM (n = 3).
z
Syn. Diffenbachia amoena Hort. and Bull.
y
Syn. Scindapsus aureus Engl.
x
Syn. Dizygotheca elegantissima (Veitch) R.Vig. and Guillaumin.
Table 2. Accumulated removal concentration
of volatile organic compounds (VOCs) by
plastic pot (10 cm, 500 cc) containing soilless
media without plant 3 h and 6 h after
introduction of five representative VOCs
[benzene, toluene, octane, trichloroethylene
(TCE), and a-pinene].
VOC
Accumulated removal concn by plastic
pot containing media (mgm
–3
)
3h 6h
Benzene 0.34 ± 0.06 0.38 ± 0.05
Toluene 1.13 ± 0.06 1.21 ± 0.04
Octane 0.35 ± 0.08 0.47 ± 0.07
TCE 1.00 ± 0.17 1.10 ± 0.08
a-Pinene 1.03 ± 0.17 1.13 ± 0.07
Data are means ± SEM (n = 3).
1378 HORTSCIENCE VOL. 44(5) AUGUST 2009

M = the concentration of VOC in the jar
containing only the plastic pot and
media (mgm
–3
) (Table 2)
L = total leaf area (m
2
)
T = VOC exposure time (h)
Statistical analysis. Analysis of variance
and Duncan’s multiple range test were car-
ried out by using the SAS system for Win-
dows v8 (SAS Institute, Cary, NC).
Results and Discussion
The initial concentrations of benzene,
toluene, octane, TCE, and a-pinene within
the container were 9.66 ± 0.03 (30.9), 9.66 ±
0.07 (59.1), 9.49 ± 0.06 (36.4), 11.00 ± 0.07
(44.3), and 9.82 ± 0.20 (54.7) ppm (mgm
–3
),
respectively. The concentration of each
VOC, after subtraction of the concentration
of VOC in jars containing the pot and media
without a plant (Table 2) from that in the
sample jar with plant, decreased with expo-
sure duration, indicating VOC removal by the
plants (Fig. 1). Because the test plants varied
in size and foliar surface area, the removal
efficiency for each VOC was expressed on a
leaf area basis to allow identification of
species with superior removal efficiency.
VOC removal represents the effect of the
plant and subterranean micro-organisms
associated with the plant in the potting media,
the latter of which is known to be an
important contributor (Wood et al., 2002).
The removal efficiency varied substan-
tially among the species tested: benzene
(0.03 to 5.54 mgm
–3
m
–2
h
–1
), toluene (1.54
to 9.63), octane (0 to 5.58), TCE (1.48 to
11.08), a-pinene (2.33 to 12.21), and total
VOC (5.55 to 44.04) (Table 3). The results
demonstrate the rate of removal varies
depending on the VOC in question and the
plant species present.
Benzene. Six species with superior ben-
zene removal efficiency were identified:
Hemigraphis alternata (5.54 mgm
–3
m
–2
h
–1
),
Tradescantia pallida (3.86), Hedera helix
(3.63), Fittonia argyroneura (2.74), Aspara-
gus densiflorus (2.65), and Hoya carnosa
(2.21) (Table 3; Fig. 1A). H. alternata had
the highest removal efficiency and the high-
est accumulated removal of benzene at 3 h
and 6 h. At 3 h, five species classified as
having high removal efficiency were not
statistically significant in their accumulated
removal concentrations; however, by 6 h,
there were significant differences (Fig. 1A).
Sansevieria trifasciata (1.76), Ficus benja-
mina (1.66), Polyscias fruticosa (1.53), Guz-
mania sp. (1.46), Anthurium andreanum
(1.31), and Peperomia clusiifolia (1.20) were
classified as having an intermediate benzene
removal efficiency; the remainder had very
low benzene removal efficiencies (Table 3).
Toluene. H. alternata had the highest tolu-
ene removal efficiency (9.63 mgm
–3
m
–2
h
–1
)
followed by T. pallida (9.10), H. helix (8.25),
A. densiflorus (7.44), H. carnosa (5.81), F.
argyroneura (5.09), and F. benjamina (5.06)
(Table 3; Fig. 1B). The plants were much
more effective in removing toluene than
benzene, a finding corroborated by Yoo et al.
(2006). The rate of toluene removal during the
initial 3-h exposure was more rapid compared
with the second 3 h of exposure. Toluene
removal occurs through adsorption to the plant
Fig. 1. Accumulated removal of (A) benzene, (B) toluene, (C) octane, (D) trichloroethylene, and (E)
a-pinene by plants with superior volatile organic compound removal efficiency over 6 h during the
day. Plots with different letters at the same time are significantly different by Duncan’s multiple range
test (P< 0.05). The solid squares, solid triangles, solid circles, open squares, open triangles, and open
circles represent the following species in sequence: (A)Hemigraphis alternata,Tradescantia pallida,
Hedera helix,Fittonia argyroneura,Asparagus densiflorus, and Hoya carnosa;(B)H. alternata,T.
pallida,H. helix,A. densiflorus,H. carnosa, and F. argyroneura;(C)H. alternata,H. helix,Ficus
benjamina,H. carnosa,A. densiflorus, and Polyscias fruticosa;(D)H. alternata,H. helix,T. pallida,A.
densiflorus,F. argyroneura, and H. carnosa; and (E)H. helix,H. alternata,A. densiflorus,T. pallida,
F. benjamina, and H. carnosa.
HORTSCIENCE VOL. 44(5) AUGUST 2009 1379

surface and absorption through stomatal
uptake; the removal rate depends on the
number of stomata and the cuticular structure
(Jen et al., 1995; Ugrekhelidze et al., 1997).
Octane. H. alternata had the highest octane
removal efficiency (5.58 mgm
–3
m
–2
h
–1
)fol-
lowed by H. helix (5.10), F. benjamina (3.98),
H. carnosa (3.80), A. densiflorus (3.76), and
P. fruticosa (3.43) (Table 3; Fig. 1C). Pelar-
gonium graveolens had no effect on octane
concentration, whereas Maranta leuconeura
(0.51 mgm
–3
m
–2
h
–1
), Schefflera elegantis-
sima (0.65), Syngonium podophyllum (0.76),
Calathea roseopicta (0.83), and Epipremnum
aureum (0.86) had very low octane removal
efficiencies. The removal of octane, an ali-
phatic hydrocarbon, by indoor plants has not
been reported; however, hexane, also an
aliphatic hydrocarbon, was removed by Dra-
caena deremensis and Spathiphyllum wallisii
(Wood et al., 2002).
Trichloroethylene. The six species that
effectively removed toluene also had supe-
rior TCE removal efficiencies: H. alternata
(11.08 mgm
–3
m
–2
h
–1
), H. helix (8.07), T.
pallida (7.95), A. densiflorus (6.69), F. argyr-
oneura (6.15), and H. carnosa (5.79) (Table
3; Fig. 1D). Similar to toluene, the highest
rate of TCE removal was during the initial 3
h, declining subsequently with the exception
of T. pallida in which the rate remained fairly
consistent. Chlorophytum comosum, which
was previously reported to remove TCE
(Cornejoet al., 1999), had an intermediateTCE
removal efficiency (2.86 mgm
–3
m
–2
h
–1
).
a-Pinene. H. helix had the highest a-pinene
removal efficiency (13.28 mgm
–3
m
–2
h
–1
)of
the 28 species tested followed by H. alternata
(12.21), A. densiflorus (11.40), T. pallida
(10.45), F. benjamina (8.68), H. carnosa
(8.48), and P. fruticosa (8.30) (Table 3; Fig.
1E).
Based on the total VOC removal effi-
ciency, the plants were classified into supe-
rior, intermediate, and poor categories (Table
3). Five species (i.e., H.alternata,H.helix, T.
pallida, A.densiflorus, and H.carnosa) with
superior phytoremediation potential were
identified. Their total VOC removal ranged
from 26.08 to 44.04 mgm
–3
m
–2
h
–1
and they
effectively removed each of the test com-
pounds. In contrast, the total VOC removal
efficiency of the six plants classified as having
an intermediate phytoremediation potential
ranged from 17.46 to 24.13 mgm
–3
m
–2
h
–1
,
whereas those with poor efficiencies ranged
from 5.55 to 12.98 mgm
–3
m
–2
h
–1
.
There were no discernible trends in VOC
removal potential based on taxonomical
relatedness. However, the Araceae family
[e.g., E.aureum (6.71 mgm
–3
m
–2
h
–1
), S.
podophyllum (7.04), P.scandens ssp. oxy-
cardium (7.26), Dieffencachia seguine
(8.05), S.wallisii (11.15)] generally had poor
phytoremediation potential, whereas repre-
sentatives of the Araliaceae family had, in
general, a far better removal potential [e.g.,
H.helix (38.33 mgm
–3
m
–2
h
–1
), P.fruticosa
(21.53), and S.elegantissima (17.46)].
The volatiles tested in this study are
commonly found in buildings. They can
adversely affect indoor air quality and have
a potential to seriously compromise the
health of exposed individuals (Mitchell
et al., 2007; Suh et al., 2000; Zabiega1a,
2006). Benzene and toluene are known to
originate from petroleum-based indoor coat-
ings, cleaning solutions, plastics, environ-
mental tobacco smoke, and exterior exhaust
fumes emanating into the building; octane
from paint, adhesives, and building materi-
als; TCE from tap water, cleaning agents,
insecticides, and plastic products; and
a-pinene from synthetic paints and odorants.
Some of the common indoor VOCs are
known carcinogens (Jones, 1999; Newman
et al., 1997) and at sufficiently high concen-
trations, a number of VOCs are harmful to
plants (Cape, 2003). Visible injury to plants
in this study was not observed.
Although a diverse cross-section of plants
was capable of removing the VOCs tested
(Table 3), removal efficiency varied within a
single species as a result of differences in
the chemical properties of the individual
compounds (e.g., polarity, vapor pressure,
molecular weight, solubility, dissociation),
an effect previously noted by Yoo et al.
(2006). The fate of VOCs (e.g., accumulation,
Table 3. Removal efficiency based on leaf area of five representative volatile organic compounds (VOCs) [benzene, toluene, octane, trichloroethylene (TCE), and
a-pinene] of 28 indoor plants over 6 h during the day.
Plant
VOC removal efficiency (mgm
–3
m
–2
h
–1
)
Benzene Toluene Octane TCE a-Pinene Total
Superior removal efficiency
Hemigraphis alternata 5.54 ± 0.29 9.63 ± 0.94 5.58 ± 0.68 11.08 ± 0.99 12.21 ± 1.61 44.04 ± 2.98
Hedera helix 3.63 ± 0.33 8.25 ± 0.64 5.10 ± 0.49 8.07 ± 0.77 13.28 ± 0.95 38.33 ± 3.17
Tradescantia pallida 3.86 ± 0.58 9.10 ± 1.17 2.76 ± 1.08 7.95 ± 1.20 10.45 ± 1.78 34.12 ± 5.52
Asparagus densiflorus 2.65 ± 0.24 7.44 ± 0.28 3.76 ± 0.64 6.69 ± 0.49 11.40 ± 0.78 31.94 ± 2.40
Hoya carnosa 2.21 ± 0.21 5.81 ± 0.67 3.80 ± 0.62 5.79 ± 0.75 8.48 ± 1.17 26.08 ± 3.40
Intermediate removal efficiency
Ficus benjamina 1.66 ± 0.07 5.06 ± 0.19 3.98 ± 0.19 4.74 ± 0.15 8.68 ± 0.40 24.13 ± 0.86
Polyscias fruticosa 1.53 ± 0.08 4.29 ± 0.04 3.43 ± 0.08 3.98 ± 0.16 8.30 ± 0.12 21.53 ± 0.42
Fittonia argyroneura 2.74 ± 0.28 5.09 ± 0.23 1.77 ± 0.25 6.15 ± 0.36 4.30 ± 0.39 20.05 ± 1.46
Sansevieria trifasciata 1.76 ± 0.48 4.97 ± 0.70 2.73 ± 0.50 4.61 ± 0.81 5.49 ± 1.31 19.56 ± 3.68
Guzmania sp. 1.46 ± 0.25 4.04 ± 0.56 2.07 ± 0.24 4.01 ± 0.49 6.43 ± 0.55 18.01 ± 1.77
Anthurium andreanum 1.31 ± 0.12 3.60 ± 0.37 2.45 ± 0.24 3.58 ± 0.35 5.85 ± 0.54 16.78 ± 1.59
Schefflera elegantissima
z
0.66 ± 0.19 4.94 ± 0.37 0.65 ± 0.46 3.87 ± 0.10 7.33 ± 0.36 17.46 ± 0.81
Poor removal efficiency
Peperomia clusiifolia 1.20 ± 0.10 2.75 ± 0.11 2.03 ± 0.01 2.40 ± 0.13 4.61 ± 0.14 12.98 ± 0.39
Chlorophytum comosum 0.75 ± 0.11 3.18 ± 0.14 1.70 ± 0.08 2.86 ± 0.13 4.17 ± 0.21 12.66 ± 0.54
Howea belmoreana 0.80 ± 0.10 2.95 ± 0.32 1.81 ± 0.28 2.71 ± 0.28 4.25 ± 0.67 12.52 ± 1.64
Spathiphyllum wallisii 0.75 ± 0.11 2.52 ± 0.13 1.55 ± 0.21 2.25 ± 0.19 4.09 ± 0.21 11.15 ± 0.83
Schefflera arboricola 0.44 ± 0.07 2.25 ± 0.23 1.75 ± 0.13 1.78 ± 0.17 4.18 ± 0.34 10.40 ± 0.84
Codiaeum variegatum 0.89 ± 0.04 2.28 ± 0.08 1.21 ± 0.03 2.34 ± 0.10 3.61 ± 0.09 10.33 ± 0.31
Calathea roseopicta 0.94 ± 0.18 2.70 ± 0.38 0.83 ± 0.14 2.32 ± 0.40 3.25 ± 0.58 10.04 ± 1.62
Aspidistra elatior 0.53 ± 0.08 2.22 ± 0.24 1.22 ± 0.17 2.00 ± 0.20 3.17 ± 0.40 9.14 ± 1.06
Maranta leuconeura 0.74 ± 0.19 2.67 ± 0.28 0.51 ± 0.19 2.35 ± 0.40 2.76 ± 0.67 9.03 ± 1.68
Dracaena fragrans 0.55 ± 0.01 2.01 ± 0.08 1.18 ± 0.08 1.90 ± 0.09 3.31 ± 0.19 8.95 ± 0.44
Ficus elastica 0.38 ± 0.07 2.29 ± 0.11 1.20 ± 0.13 1.75 ± 0.19 2.66 ± 0.12 8.28 ± 0.56
Dieffenbachia seguine
y
0.18 ± 0.04 2.03 ± 0.10 1.01 ± 0.10 1.83 ± 0.07 2.99 ± 0.20 8.05 ± 0.39
Philodendron scandens ssp. oxycardium 0.49 ± 0.08 1.80 ± 0.11 0.98 ± 0.06 1.66 ± 0.16 2.33 ± 0.12 7.26 ± 0.52
Syngonium podophyllum 0.03 ± 0.02 1.84 ± 0.15 0.76 ± 0.16 1.67 ± 0.22 2.75 ± 0.17 7.04 ± 0.70
Epipremnum aureum
x
0.44 ± 0.05 1.54 ± 0.15 0.86 ± 0.09 1.52 ± 0.16 2.34 ± 0.21 6.71 ± 0.64
Pelargonium graveolens 0.03 ± 0.02 1.67 ± 0.29 0.00 ± 0.00 1.48 ± 0.44 2.37 ± 0.26 5.55 ± 0.99
Data are means ± SEM (n = 3).
z
Syn. Dizygotheca elegantissima (Veitch) R.Vig. and Guillaumin.
y
Syn. Diffenbachia amoena Hort. and Bull.
x
Syn. Scindapsus aureus Engl. f.
1380 HORTSCIENCE VOL. 44(5) AUGUST 2009

adsorption, absorption, penetration, trans-
portation, metabolism), therefore, depends
on the chemical characteristics of each volatile
(Cape, 2003; Deinum et al., 1995; Korte
et al., 2000) and the physical and chemical
characteristics of the plants. Lipophilic com-
pounds more readily penetrate the cuticular
surface of plants, expediting uptake in contrast
to compounds that are largely restricted to
stomatal penetration (Deinum et al., 1995;
Schmitz et al., 2000). In addition, the ability
to metabolize VOCs varies widely among
species and volatiles (Beattie and Seibel,
2007; Cape, 2003; Deinum et al., 1995; Jen
et al., 1995). Therefore, a better understanding
of the basic physical and chemical factors
modulating the phytoremediation processes in
the most efficient species is needed.
Conclusions and Summary
Of the 28 species tested, H. alternata,H.
helix,H. carnosa, and A. densiflorus had
superior removal efficiencies for each of
the test compounds (i.e., benzene, toluene,
octane, TCE, and a-pinene). Likewise, T.
pallida had superior removal efficiencies for
four of the compounds (i.e., benzene, toluene,
TCE, and a-pinene). H. alternata, in partic-
ular, had the highest removal efficiency
for four of the compounds (benzene, toluene,
octane, and TCE). Indoor plants are known
to confer significant psychological and phys-
ical benefits to individuals living/working in
environments where they are present
[e.g., reduced stress, increased task perfor-
mance, and decreased symptoms of ill health
(Bringslimark et al., 2007; Son, 2004)]. Based
on this and other studies, plants also have the
potential to significantly improve the quality of
indoor air. Their increased use in both ‘‘green’’
and traditional buildings could have a tremen-
dous positive impact on the ornamental indus-
try by increasing customer demand and volume
of sales. Further studies focusing on screening
additional plant species for superior VOC
removal efficiencies are warranted.
Literature Cited
Beattie, G.A. and J.R. Seibel. 2007. Uptake and
localization of gaseous phenol and p-cresol in
plant leaves. Chemosphere 68:528–536.
Bringslimark, T., T. Hartig, and G.G. Patil. 2007.
Psychological benefits of indoor plants in
workplaces: Putting experimental results into
context. HortScience 42:581–587.
Cape, J.N. 2003. Effects of airborne volatile
organic compounds on plants. Environ. Pollut.
122:145–157.
Cohen, Y. 1996. Volatile organic compounds in the
environment: A multimedia perspective, p. 7–
32. In: Wang, W., J. Schnoor, and J. Doi (eds.).
Volatile organic compounds in the environ-
ment. ASTM STP 1261. American Society for
Testing and Materials, West Conshohocken, PA.
Cornejo, J.J., F.G. Munoz, C.Y. Ma, and A.J.
Stewart. 1999. Studies on the decontamination
of air by plants. Ecotoxicol. 8:311–320.
Darlington, A., M. Chan, D. Malloch, C. Pilger,
and M.A. Dixon. 2000. The biofiltration of
indoor air: Implications for air quality. Indoor
Air 10:39–46.
Deinum, G., A.C. Baart, D.J. Bakker, J.H. Duyzer,
and K. Dick Van Den Hout. 1995. The influ-
ence of uptake by leaves on atmospheric
deposition of vapor-phase organics. Atmos.
Environ. 29:997–1005.
Destaillats, H., R.L. Maddalena, B.C. Singer, A.T.
Hodgson, and T.E. McKone. 2008. Indoor
pollutants emitted by office equipment: A
review of reported data and information needs.
Atmos. Environ. 42:1371–1388.
Ingrosso, G. 2002. Free radical chemistry and its
concern with indoor air quality: An open
problem. Microchem. J. 73:221–236.
Jen, M.S., A.M. Hoylman, N.T. Edwards, and B.T.
Walton. 1995. Experimental method to mea-
sure gaseous uptake of
14
C-toluene by foliage.
Environ. Exp. Bot. 35:389–398.
Jenkins, P.L., T.J. Phillips, E.J. Mulberg, and S.P.
Hui. 1992. Activity patterns of Californians—
Use of and proximity to indoor pollutant sour-
ces. Atmos. Environ. 26:2141–2148.
Jones, A.P. 1999. Indoor air quality and health.
Atmos. Environ. 33:4535–4564.
Korte, F., G. Kvesitadze, D. Ugrekhelidze, M.
Gordeziani, G. Khatisashvili, O. Buadze, G.
Zaalishvili, and F. Coulston. 2000. Organic
toxicants and plants. Ecotoxicol. Environ. Saf.
47:1–26.
Liu, Y.J., Y.J. Mu, Y.G. Zhu, H. Ding, and N.C.
Arens. 2007. Which ornamental plant species
effectively remove benzene from indoor air?
Atmos. Environ. 41:650–654.
Maroni, M., B. Seifert, and T. Lindvall. 1995.
Indoor air quality: A comprehensive reference
book. Elsevier, Amsterdam, The Netherlands.
Mitchell, C.S., J.F.J. Zhang, T. Sigsgaard, M.
Jantunen, P.J. Lioy, R. Samson, and M.H.
Karol. 2007. Current state of the science:
Health effects and indoor environmental qual-
ity. Environ. Health Perspect. 115:958–964.
Newman, L.A., S.E. Strand, N. Choe, J. Duffy, G.
Ekuan, M. Ruszaj, B.B. Shurtleff, J. Wilmoth,
P. Heilman, and M.P. Gordon. 1997. Uptake
and biotransformation of trichloroethylene by
hybrid poplars.Environ. Sci. Technol. 31:1062–
1067.
Orwell, R.L., R.A. Wood, M.D. Burchett, J. Tarran,
and F. Torpy. 2006. The potted-plant micro-
cosm substantially reduces indoor air VOC
pollution: II. Laboratory study. Water Air Soil
Pollut. 177:59–80.
Orwell, R.L., R.L. Wood, J. Tarran, F. Torpy,
and M.D. Burchett. 2004. Removal of ben-
zene by the indoor plant/substrate microcosm
and implications for air quality. Water Air
Soil Pollut. 157:193–207.
Sandhu, A., L.J. Halverson, and G.A. Beattie.
2007. Bacterial degradation of airborne phenol
in the phyllosphere. Environ. Microbiol. 9:
383–392.
Schmitz, H., U. Hilgers, and M. Weidner. 2000.
Assimilation and metabolism of formaldehyde
by leaves appear unlikely to be of value for
indoor air purification. New Phytol. 147:307–
315.
Snyder, S.D. 1990. Building interior, plants and
automation. Prentice Hall, Englewood Cliffs, NJ.
Son, K.-C. 2004. Indoor plants help people stay
healthy. Joongang Life Pub. Co, Seoul, Korea.
Suh, H.H., T. Bahadori, J. Vallarino, and J.D.
Spengler. 2000. Criteria air pollutants and
toxic air pollutants. Environ. Health Perspect.
108:625–633.
Ugrekhelidze, D., F. Korte, and G. Kvesitadze.
1997. Uptake and transformation of benzene
and toluene by plant leaves. Ecotoxicol. Envi-
ron. Saf. 37:24–29.
Wolkoff, P. and G.D. Nielsen. 2001. Organic
compounds in indoor air—Their relevance for
perceived indoor air quality? Atmos. Environ.
35:4407–4417.
Wolverton, B.C., A. Johnson, and K. Bounds.
1989. Interior landscape plants for indoor air
pollution abatement. Final Rept. NASA, Sten-
nis Space Center, Mississippi.
Won, D., E. Lusztyk, and C.Y. Shaw. 2005. Target
VOC list. Final Rept., National Research Coun-
cil Canada.
Wood, A., R.L. Orwell, J. Tarran, F. Torry, and M.
Burchett. 2002. Potted-plant/growth media
interactions and capacities for removal of
volatiles from indoor air. J. Hort. Sci. Biotech-
nol. 77:120–129.
Yoo, M.H., Y.J. Kwon, K.-C. Son, and S.J. Kays.
2006. Efficacy of indoor plants for the removal
of single and mixed volatile organic pollutants
and physiological effects of the volatiles on
the plants. J. Amer. Soc. Hort. Sci. 131:452–
458.
Zabiega1a, B. 2006. Organic compounds in indoor
environments. Polish J. Environ. Stud. 15:383–
393.
HORTSCIENCE VOL. 44(5) AUGUST 2009 1381