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Critical Review: How Well Do House Plants Perform as Indoor Air Cleaners?

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John R. Girman
John R. Girman
John R. Girman
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Thomas Phillips at California Department of Public Health
Thomas Phillips
Hal Levin
Hal Levin
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Abstract

In the late 1980’s, research indicated that plants had the capability to remove volatile organic compounds (VOC) from indoor air. The findings were based upon chamber studies involving injection of a pollutant into a small, sealed chamber and following the pollutant decay, with and without plants present. The results were striking with removal rates up to 90% in 24 hr. Other studies examining this effect followed. Today, even a casual search of the internet will find many articles extolling the benefits of using plants as indoor air cleaners. However, there has been little critical analysis of the application of plants to actual indoor environments and only a few field studies have been conducted. A critical review of results of both laboratory chamber studies and field studies leads to the conclusion that indoor plants have little, if any, benefit for removing indoor air of VOC in residential and commercial
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Proceedings of Healthy Buildings 2009 Paper 667
Critical Review: How Well Do House Plants Perform as Indoor Air
Cleaners?
John Girman
1,*
, Tom Phillips
2
and Hal Levin
3
1
Independent Researcher
2
California Air Resources Board
3
Building Ecology Research Group
*
Corresponding email: jrgirman@aol.com
SUMMARY
In the late 1980’s, research indicated that plants had the capability to remove volatile organic
compounds (VOC) from indoor air. The findings were based upon chamber studies involving
injection of a pollutant into a small, sealed chamber and following the pollutant decay, with
and without plants present. The results were striking with removal rates up to 90% in 24 hr.
Other studies examining this effect followed. Today, even a casual search of the internet will
find many articles extolling the benefits of using plants as indoor air cleaners. However, there
has been little critical analysis of the application of plants to actual indoor environments and
only a few field studies have been conducted. A critical review of results of both laboratory
chamber studies and field studies leads to the conclusion that indoor plants have little, if any,
benefit for removing indoor air of VOC in residential and commercial buildings. Finally,
recommendations for improving future studies are presented.
KEYWORDS
Plants, pollution reduction, VOC, air cleaning
INTRODUCTION
Using plants indoors to control indoor air pollution is an attractive, popular concept and many
articles in the popular press and internet extol and promote their use as indoor air cleaners.
Today, a search of the internet will find many articles promoting the use of plants as indoor
air cleaners. While several scientific papers have been published on studies of pollutant
removal by plants in small test chambers under controlled conditions, as yet, there has been
little critical analysis of the studies and their results. Far fewer field studies have been
published. This paper will briefly review results of both laboratory chamber studies and field
studies, followed by a critical analysis of these results and the implications for indoor air
cleaning. Finally, recommendations for improving future studies are presented.
STUDIES OF POLLUTANT REMOVAL BY PLANTS
In the late 1980’s, published research indicated that plants had the capability to remove
pollutants from indoor air (e.g., Wolverton et al., 1989). The findings were based upon
studies involving the introduction of a pollutant or pollutants into a small, sealed chamber.
The chamber volumes typically ranged from 0.31 to 0.88 m
3
. Many pollutants were studied,
including benzene, xylenes, tricholorethylene and formaldehyde at concentrations of ~15 to
20 ppm. The decay of the pollutant concentration over time, with and without plants present,
was then followed. The reported results were striking, with reductions that averaged 10 to
70% in a 24-hr period. Wolverton and colleagues later conducted tests on the removal of
benzene and trichloroethylene at concentrations ranging from 0.1 to 0.4 ppm. The reported
reductions ranged from 9.2 to 90%.
Proceedings of Healthy Buildings 2009 Paper 667
Studies examining this effect by other researchers followed. For example, Wood et al. (2003)
used small chambers (0.22 m
3
) and several plant species to study the removal of benzene and
hexane over 24 hours from initial concentrations of 25 ppm for benzene and 100 ppm for
hexane. Quantitative results were not given for the concentration reductions but estimated
concentration vs. time plots indicate reductions by potted plants exposed to daily
introductions of pollutants of ~80% for benzene and ~70% for hexane.
To test the validity of laboratory results, the Associated Landscape Contractors of America
(ALCA) worked with Healthy Buildings International to conduct a field experiment (HBI,
1992). HBI sampled for toluene, xylene, 1,1,1-trichlorethane and benzene for several months
in two very similar floors of an office building in Arlington, VA, USA. Identical ventilation
systems on both floors had their outdoor air damper set and unchanged for the duration of the
study. For the first month, no plants were on either floor; for the next four months, plants
were only on the 9
th
floor; and for the last four months, plants were on both the 9
th
and the 11
th
floors. The number of plants installed by ALCA was not reported but is probably consistent
with the ALCA recommendation of one plant per 9.29 m
2
(100 ft
2
). Pollutant concentration
maxima were all in the 10’s to 100’s of ppb range: toluene, ~210 ug/m
3
; xylene, ~300 ug/m
3
;
1,1,1-trichloroethane, ~700 ug/m
3
; and benzene, ~18 ug/m
3
. The presence of plants produced
no reduction of pollutant concentrations. The authors concluded that the “levels of VOCs on
the ninth floor remained essentially the same as those on the eleventh floor throughout the
duration of the study.”
Dingle et al. (2000) reported on a field study of three portable office buildings in Perth,
Australia to test removal of formaldehyde by plants. Five plants (five species) were added to
each room every two days to a maximum of 20 plants (at 2.44 plants per m
2
) after nine days.
Two adjacent portable office buildings were used as controls with no plants. The mean
formaldehyde concentrations were about 850 ppb, except with 20 plants. The authors state
that the results show “no change in formaldehyde concentrations with the addition of 5 or 10
plants in the rooms and only an 11% reduction in formaldehyde concentrations with 20 plants
in the room.” They did not indicate that this reduction was statistically significant.
Wood et al. (2006) reported on field studies of pollutant reductions using plants in three office
buildings in Sydney, Australia. In one building, the nine offices studied were served by three
separate air-conditioning systems; in the second building, the eight offices studied were
served by a single air-conditioning system, supplying about 0.6 to 1.2 outside air changes per
hour; and the third building was naturally ventilated with windows almost always closed
during the study. In the third building, nine offices were studied in the first phase, and eight
offices were studied in the second phase. All offices were designed for single occupancy and
had 10-12 m
2
in floor area. Five-minute samples of total volatile organic compounds (TVOC)
were measured weekly with a portable photoionization detector, and individual VOC were
measured using passive samplers and gas chromatography/mass spectroscopy.
In the first and third buildings, after one month of pretesting, subsets of three office buildings
were randomly supplied with 0, 3 or 6 potted “Janet Craig” plants. Weekly measurements
were made over nine weeks and then the potted plants were randomly reassigned among the
offices for a second nine-week period. For the second part of the investigation, two types of
potted plants were used in the second and third buildings. After one month of pretesting, four
offices were randomly supplied with 0 or 6 plants. Air was sampled for nine- and five-week
periods in the second building and for nine weeks in the third building.
Proceedings of Healthy Buildings 2009 Paper 667
With no plants in the first and third buildings, the mean indoor TVOC concentration was 110
+ 15 ppb. Periods with 3 or 6 plants had a pooled TVOC concentration of 80 + 7 ppb, a 27%
reduction but only at p < 0.09. TVOC concentrations were identical with either 3 or 6 plants.
When only periods with TVOC concentrations greater than 100 ppb (9 of 18 weeks) were
used to calculate means, the reductions were statistically significant (p < 0.05): 0 plants,
mean concentrations 190 + 40 ppb; 3 plants, 105 + 15 ppb; and 6 plants, 100 + 10 ppb.
Results of the nine-week study in the second investigation were similar. Concentrations for
14 individual VOC are also reported. No trend is evident from these data: individual VOC
concentrations with 6 plants appear to be randomly higher or lower than those with no plants.
DISCUSSION
At first glance, the pollutant reduction by plants in chamber studies seems remarkable.
However, closer examination suggests otherwise. Little has changed in terms of quantitative
VOC reductions by plants in chamber studies since the early Wolverton studies, i.e., the best
result for the removal of a single injection of a VOC remains about 90% in a 24-hour period.
Thus, the conclusions of a previous analysis using a mass-balance model by Girman (reported
by Levin, 1992) are still valid. This analysis concluded that pollutant removal in a chamber of
90% in 24 hours was only 0.096 hr
-1
, less than the removal achieved by the natural ventilation
rate of a very tight house (e.g., 0.2 h
-1
). Moreover, this removal was achieved with a plant
loading in chambers (approximately one plant per 0.5 m
3
) far in excess of what would be
reasonable for indoor environments. To achieve results equivalent to those of chamber
studies would require 680 plants for a 340 m
3
(1500 ft
2
) house. Yet ACLA recommends one
plant per 9.29 m
2
(100 ft
2)
and a reduction in plant loading to 1 plant per 0.5 m
3
means that the
plants in such an environment would have a removal rate equivalent to only 0.002 hr
-1
.
Significant methodological issues also plague these chamber studies. The chamber test was a
static test method, i.e., pollutants are injected and then the pollutant decay is measured. This
does not mimic the behaviour of pollutants such as formaldehyde that are continuously
emitted. Reductions for pollutants continuously emitted would be much lower. In addition,
pollutant removal rates in these studies are too often reported as only the percent removed,
rather than mass of pollutant removed per hour per plant. This makes it difficult to translate
the results to other scenarios, e.g., to proposed use in an actual room or building, or to
compare this method to more traditional pollutant removal methods such as ventilation or air
cleaning with filters or sorbents. It should also be noted that the chamber studies used
pollutant concentrations an order of magnitude or more higher than those generally found in
indoor environments. Also, many chamber studies employed air circulation fans, which
would tend to increase pollutant losses to interior surfaces.
Results from the field studies are more difficult to assess. The methods used to measure
formaldehyde (passive monitor) and VOCs (passive sampler, photoionization detector) are not
very accurate. In addition, although ventilation dominates the VOC removal processes in
virtually all real world buildings, ventilation was not measured in any of these studies. It is
not possible to obtain meaningful quantitative results of pollutant removal in a field study
without also measuring ventilation rates. The ventilation rate variability in most buildings is
simply too large a confounder.
With this caveat firmly in mind, it is hardly surprising that the HBI study failed to find any
effect on pollutant removal by plants, despite a reasonably strong study design in terms of
using controls. The study by Dingle et al. found only an 11% reduction in formaldehyde with
Proceedings of Healthy Buildings 2009 Paper 667
the highest loading of plants (20 plants in a room or a loading of 2.44 plants per m
2
), which is
not feasible in the real world and is probably not statistically significant.
Only in the field study by Wood et al. are pollutant reductions statistically significant, and
then only when indoor TVOC concentrations are above 100 ppb. However, these results are
not consistent with the fact that doubling the number of plants did not cause a statistically
significant reduction (i.e., a reduction of only 105 + 15 ppb to. 100 + 10 ppb) and with the fact
that individual VOC concentrations did not appear to be reduced. It is possible that variations
in ventilation may have been responsible for any apparent pollutant reductions. In this regard,
the indoor carbon dioxide (CO
2
) concentrations in the buildings ranged from 285 to 420 ppm
(outdoor CO
2
was not sampled), suggesting that building ventilation rates were high,
occupancy was low, or both conditions existed during the study. It is also likely that sampling
for TVOC for 5 minutes per week is insufficient to characterize indoor concentrations.
CONCLUSIONS
Several laboratory studies have shown that plants can remove airborne VOC. However, a
careful examination of studies does not find convincing evidence that the use of plants indoors
can result in meaningful reductions in indoor VOC concentrations. Several improvements
should to be made to studies intended to demonstrate that plants can be used to improve
indoor quality. Concentrations used in chamber studies should be representative of
concentrations found in actual indoor environments. Also, such studies should use analytical
methods of high accuracy and sensitivity to measure VOC concentrations and should focus on
individual VOC. They should also use mass-balance models to design and assess study
results. Chamber study results should be reported as mass of pollutant removed per hour per
plant to facilitate comparisons with other removal methods to assist building designers,
managers and owners in determining whether using plants is an appropriate pollution control
technique. For the same reasons, plant loadings should be reported. Finally, to be
convincing, any field study must also measure ventilation rates since ventilation rates
typically dominate pollutant removal processes. At present, it is premature to recommend that
using plants indoor is viable means of controlling indoor air pollution.
DISCLAIMER
The opinions expressed in this paper are those of the authors and do not necessarily reflect the
positions of the California Air Resources Board.
REFERENCES
Dingle P, Tapsell P, and Hu S. 2000. Reducing formaldehyde exposure in office
environments using plants. Bull. Environ. Contam. Toxicol., 64, 302-308.
HBI. 1992. Can plants help clean up the indoor air?, Healthy Buildings International
Magazine, 2(1), 10-11.
Levin H. 1992. Can house plants solve IAQ problems? Indoor Air Bulletin, 2(2), 1-5.
Wolverton B.C, Johnson A, and Bounds K. 1989. Interior landscape plants for indoor air
pollutant abatement, Final Report – Sept 1989. Stennis Space Center, National
Aeronautics and Space Administration, Mississippi, USA, 25 pages.
Wood R.A, Orwell R.L, Tarran J., Torpy F, and Burchett M. 2003. Potted-plant/growth
media interactions and capacities for removal of volatiles from indoor air. In:
Proceedings of Health Buildings 2003 – HB2003, Singapore, 1, pp. 441-445.
Wood R.A, Burchett M.D, Alquezar R, Orwell R.L, Tarran J, and Torpy F. 2006. The
potted-plant microsm substantially reduces indoor air voc pollution: I. office field-study.
Water, Air and Soil Pollution, 175, 163-180.

Supplementary resource (1)

Can House Plants Solve IAQ Problems
Data
May 2015
John R. Girman · Thomas Phillips · Hal Levin
... A large majority of previous work has focused on plants' supposed capacity to improve indoor air quality (IAQ)-whether through the removal of indoor air pollutants [1,[6][7][8][9][10][11], CO 2 adsorption [12] or ion regulation [13]-reaching no scientific consensus, although many studies claim to have found positive correlations. Some studies have been very critical, pointing out both low removal rates [14] and methodological inconsistencies [8,14] in large part due to important environmental differences in conditions between real indoor environments and the experimental chambers where tests have been conducted. ...
... A large majority of previous work has focused on plants' supposed capacity to improve indoor air quality (IAQ)-whether through the removal of indoor air pollutants [1,[6][7][8][9][10][11], CO 2 adsorption [12] or ion regulation [13]-reaching no scientific consensus, although many studies claim to have found positive correlations. Some studies have been very critical, pointing out both low removal rates [14] and methodological inconsistencies [8,14] in large part due to important environmental differences in conditions between real indoor environments and the experimental chambers where tests have been conducted. ...
... The analysis highlighted a broad diversity in the metrics used. This result is in accordance with a number of other studies which have also highlighted inconsistent metrics: the metrics were found to be either too different to enable comparisons between studies [14] or difficult to scale up and contextualize the results in other scenarios (in IAQ studies, suggested measures are the mass of the pollutant removed per hour per plant [8], and clean air delivery rate CADR in m 3 /h [14]). ...
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... A few field campaigns have tried to measure the impact of plants within indoor environments, although Girman et al. [60] documented in detail the likely inaccuracies of the measuring equipment used in these studies. More importantly, none of them controlled or measured the outdoor air exchange rate. ...
... Only two publications were found that not only acknowledge these issues, but explicitly refute the notion that common houseplants improve indoor air quality. They were written by Girman et al. [60] and Levin [63]. Those works, authored by indoor air and building scientists, discuss in detail the history and limitations of the chamber and field studies, and provide a mass balance calculation that highlights the predicted ineffectiveness of using potted plants to remove VOCs from indoor air. ...
... This assessment is in strong agreement with the conclusions of Girman et al. [60] and Levin [63]. Using similar mass balance calculations and the most generous selection of the early published Wolverton et al. [49] data, Levin [63] determined that a~140 m 2 house (1500 ft 2 ) would require 680 houseplants (i.e., ρ p = 4.9 plants/m 2 ) for the removal rate of VOCs by plants indoors to just reach 0.096 h −1 . ...
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... Several studies had been conducted on the positive impact of these plants to humans. These are some of the well-known benefits of indoor plants that are backed by researches conducted in the past (NASA, 1989;Girman et al., 2009;Kim et al., 2014;Sevik et al., 2017). ...
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... It is important to assess the possible negative consequences of introducing large numbers of plants into indoor environments. There has been little critical analysis on the application of plants and the actual indoor environment [107]. Some green plants are not suitable to be placed indoors, because they harm people [108][109].For example, flowering plants with strong fragrances (e.g., Tulipa gesneriana L. and Telosma cordata (Burm. ...
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... Thus, hydrophilic contaminants such as formaldehyde can hardly enter the plant through the cuticle that is the adipose tissue, while lipophilic contaminants such as benzene can be easily absorbed through the cuticle, in addition to the stomata (Kim et al. 2008;Hörmann et al. 2018;Teiri et al. 2018a). However, some studies have concluded that the contribution of the aerial parts of plants on the removal of VOCs from indoor air is not significant (Girman et al. 2009;Llewellyn and Dixon 2011;Hanoune et al. 2013;Hörmann et al. 2018). ...
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In recent decades, indoor air pollution has become a major concern due to its adverse health effects on the inhabitants. The presence of fine particles (PM2.5) and hazardous volatile organic compounds (VOCs), such as formaldehyde and benzene, in indoor air and their proven carcinogenic effects, has raised the attention of health authorities. Their very difficult and expensive removal by chemical and mechanical methods has led researchers to seek an economical and environmentally friendly technique. The use of plants in different ways such as potted plants or green walls is considered as a potential green solution for the improvement of indoor air quality and the health level of its inhabitants. A review of the literature cited in this paper suggests that plants absorb some of the pollutants, such as particles directly and remove some pollutants such as VOCs indirectly through biological transfer or by using microorganisms. This review paper discusses the types of plants that have been used for the phytoremediation of airborne pollutants and the routes and mechanisms for removing the pollutants. Removal pathways of the pollutants by aerial parts of the plants, the growth media along with the roots and their microorganisms in the rhizosphere part were also discussed. Sensitive analysis of extracted data from the literature outlined the most useful types of plants and the appropriate substrate for phytoremediation. Also, it showed that factors affecting the removal efficiency such as light intensity and ambient temperature, behave differently depending on pollutants and plants types.
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Low indoor air quality is an increasingly important problem due to the spread of urbanization. Because people spend most of their time inside, poor indoor air quality causes serious human health issues, resulting in significant economic losses. In this work, the current state of affairs is presented and analyzed, focusing on the current problems and the available solutions to improve the quality of indoor air, and the use of nature-based solutions. These involve the cultivation of microalgae in closed photobioreactors. In these systems, photosynthetic organisms can capture CO2 and other pollutants generated in indoor environments, which they use to grow and develop biomass. Several possible layouts for the implementation of microalgae-based indoor air cleaning systems are presented, taking into account the systems that are currently available at a commercial scale. A critical analysis of the microalgae indoor purification systems is presented, highlighting their advantages and disadvantages, and suggesting potential improvements and future lines of research and development in the area.
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... The natural fluctuations of visual stimuli created by water can reduce stress, increase relaxation, decrease heart rate and blood pressure, and improve concentration and memory [23]. The presence of indoor air purifying plants can help purify indoor air pollution [24,25], easing the work of air purifiers and the one coming from the air conditioner. Such indoor plants can include garden mum (Chrysanthemum morifolium), spider plant (Chlorophytum Comosum "Vittatum"), dracanea (Dracanea spp.), ficus (Ficus benjamina), peace lily (Spathiphyllum sp.), boston fern (Nephrolepis exaltata v. Bostoniensis), snake plant (Sansevieria trifasciata), bamboo palm (Chamaedorea seifritzii), aloe vera (Aloe vera), chinese evergreen (Aglaonema modestum), english ivy (Hedera helix), and gerbera daisy (Gerbera jamesonii) [24,26]. ...
Energy-efficient Lighting and Biophilic Design Concept to Boost Reading Interest in Social Facilities’ Library
Article
Full-text available
  • Jul 2020
Library in public and social facilities such as schools, mosques, churches and training centers has never become the main priority service unless it is intended accordingly. The good thing is, the library in such facilities always merges with other social functions such as special classes, gathering room or even dining room which is an addition to its original function: the reading room. Department of Architecture Universitas Indonesia, together with “Smandel 95 Berbagi Kasih Program” has conducted (has been conducting kalau aktivitasnya masih berlangsung) community engagement program, funded by the Directorate of Research and Community Engagement Universitas Indonesia, in an orphanage in Jakarta, namely Yayasan Tanjung Barat. The aim of this activity is to increase the occupant’s hobby in reading without renouncing the original activities through an energy-efficient and biophilic concept. Software-based lighting simulation and biophilic intervention concept were conducted to get the optimum result, a part of the design development through multi-discussions with the occupants and observations. Through this study, the energy efficiency from lighting intervention and the biophilic design presence in this library can be increased by 59% and 69% respectively.
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... Since then, a multitude of tests and studies on the usage of plants to alleviate indoor air quality problems have been carried out, with different applications for various indoor air pollutants as well as their efficiencies in different conditions, as summarized in Table 3. Although plants seem remarkable at first, some researchers claim it is non-beneficial as the number of plants that must be used is far more than what the indoor space could accommodate [20]. Most research has focused on traditional potted indoor plants; however, newer developments in horticultural technology, specifically green wall systems, have received far less research, with much recent research focused on exploring other aspects of the indoor environment including cooling potential and humidity regulation [21]. ...
A dynamic botanical air purifier (DBAP) with activated carbon root-bed for reducing indoor carbon dioxide levels
Article
Full-text available
  • Nov 2019
Indoor Air Quality (IAQ), is important in buildings because it can affect an occupant’s health and productivity. Carbon Dioxide (CO 2 ) is a main indicator of IAQ. 4 decades ago, researchers discovered the potential for indoor plants to remediate indoor air pollutants via photosynthesis. This study investigates the CO 2 removal rate when a Maranta Leuconeura is paired with activated carbon (AC), as well as a mechanical ventilation system that draws air into its root-bed making it an active system (DBAP). The results were compared to passive systems i.e plant with AC, potting soil etc. The study was conducted in a 0.7 m ³ Plexiglas chamber with initial CO 2 concentrations of 1500±100 ppm while initial temperatures ranged between 24 ± 2°C for a duration of 6 hours continuously. Results showed, the DBAP reduced CO 2 levels by 40.90% while a passive plant with AC only, was able to lower CO 2 levels by 15.20%. The other passive systems did not reduce CO 2 levels. All systems were able to raise humidity and reduce temperature in the chamber, with the exception of the DBAP, which slightly increased the temperature in the chamber.
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INDOOR AIR POLLUTION: SOURCES, HEALTH IMPACTS AND CONTROL
Article
Full-text available
  • Apr 2018
Indoor air pollution has nowadays become a severe environmental hazard affecting the well-being of humans. The term "building related illness" has been coined to describe various illness and problems related to specific airborne contaminants in buildings, which results in indoor pollution. Modern homes and office buildings are now days so constructed that they trap pollutants like benzene, formaldehyde, trichloroethylene (TCE), etc. According to the US EPA (Environmental Protection Agency), indoor pollutants levels are 100 times higher than outdoor levels. The way to control the indoor pollution is by restricting the polluting sources. A little modification and change in our daily life pattern can overcome these issues. In addition, adopting the practice of house plants will not only decorate our homes but also filter the harmful and toxic chemicals from our indoor air. The present study strategically elucidates solutions to these problems.
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The Potted-Plant Microcosm Substantially Reduces Indoor Air VOC Pollution: I. Office Field-Study
Article
Full-text available
  • Sep 2006
Volatile organic compounds (VOCs) are major contaminants of indoor air, with concentrations often several times higher than outdoors. They are recognized as causative agents of “building-related illness” or “sick-building syndrome”. Our previous laboratory test-chamber studies have shown that the potted-plant/root-zone microorganism microcosm can eliminate high concentrations of air-borne VOCs within 24 hours, once the removal response has been induced by an initial dose. However, the effectiveness of the potted-plant microcosm in ‘real-world’ indoor spaces has never previously been tested experimentally. This paper reports the results of a field-study on the effects of potted-plant presence on total VOC (TVOC) levels, measured in 60 offices (12 per treatment), over two 5–9 week periods, using three planting regimes, with two ‘international indoor-plant’ species. Fourteen VOCs were identified in the office air. When TVOC loads in reference offices rose above 100 ppb, large reductions, of from 50 to 75% (to <100 ppb), were found in planted offices, under all planting regimes The results indicate that air-borne TVOC levels above a threshold of about 100 ppb stimulate the graded induction of an efficient metabolic VOC-removal mechanism in the microcosm. Follow-up laboratory dose-response experiments, reported in the following paper, confirm the graded induction response, over a wide range of VOC concentrations. The findings together demonstrate that potted-plants can provide an efficient, self-regulating, low-cost, sustainable, bioremediation system for indoor air pollution, which can effectively complement engineering measures to reduce indoor air pollution, and hence improve human wellbeing and productivity.
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Potted-plant/growth media interactions and capacities for removal of volatiles from indoor air
Article
  • Jan 2002
Results are presented of an investigation into the capacity of the indoor potted-plant/growth medium microcosm to remove air-borne volatile organic compounds (VOCs) which contaminate the indoor environment, using three plant species, Howea forsteriana (Becc. (Kentia palm), Spathiphyllum wallisii Schott. 'Petite' (Peace Lily) and Dracaena deremensis Engl. 'Janet Craig'. The selected VOCs were benzene and n-hexane, both common contaminants of indoor air. The findings provide the first comprehensive demonstration of the ability of the potted-plant system to act as an integrated biofilter in removing these contaminants. Under the test conditions used, it was found that the microorganisms of the growth medium were the "rapid-response" agents of VOC removal, the role of the plants apparently being mainly in sustaining the root microorganisms. The use of potted-plants as a sustainable biofiltration system to help improve indoor air quality can now be confidently promoted. The results are a first step towards developing varieties of plants and associated microflora with enhanced air-cleaning capacities, while continuing to make an important contribution to the aesthetics and psychological comfort of the indoor environment.
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Interior Landscape Plants for Indoor Air Pollution Abatement
Article
  • Oct 1989
In this study, the leaves, roots, soil, and associated microorganisms of plants have been evaluated as a possible means of reducing indoor air pollutants. Additionally, a novel approach of using plant systems for removing high concentrations of indoor air pollutants such as cigarette smoke, organic solvents, and possibly radon has been designed from this work. This air filter design combines plants with an activated carbon filter. The rationale for this design, which evolved from wastewater treatment studies, is based on moving large volumes of contaminated air through an activated carbon bed where smoke, organic chemicals, pathogenic microorganisms (if present), and possibly radon are absorbed by the carbon filter. Plant roots and their associated microorganisms then destroy the pathogenic viruses, bacteria, and the organic chemicals, eventually converting all of these air pollutants into new plant tissue. It is believed that the decayed radon products would be taken up the plant roots and retained in the plant tissue.
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Reducing Formaldehyde Exposure in Office Environments Using Plants
Article
  • Mar 2000
Formaldehyde is a toxic substance with adverse health effects detectable at low concentrations. Formaldehyde causes irritation of the eyes, skin and respiratory tract, wheezing, nausea, coughing, diarrhoea, vomiting, dizziness and lethargy at levels as low as 50 parts per billion (ppb) (0.05 ppm) (Horvath et al, 1988). Formaldehyde has also been associated with aggravation of asthma, emphysema, hayfever and allergy problems at low levels (EPA, 1987). Formaldehyde is currently considered a potential carcinogen to humans (EPA, 1987). Formaldehyde is a ubiquitous gas found in elevated concentrations in indoor environments. Concentrations of formaldehyde are typically an order of magnitude greater inside buildings compared to outdoor air (Godish, 1990). Formaldehyde concentrations are particularly high in portable buildings due to the presence of more formaldehyde emitting materials and the relatively smaller interior volumes of air (Sexton et al, 1983). Major sources of formaldehyde indoors are pressed wood products, such as particle board and plywood (Elbert, 1995: Myer and Hermans, 1985), and urea formaldehyde foam insulation (Spengler and Sexton, 1983). Other sources include carpets, curtains, floor linings, paper products, cosmetics and soaps, tobacco smoke and gas combustion (Spengler and Sexton, 1983: Godish, 1990). Methods to reduce indoor formaldehyde include source removal or use of non- polluting materials, emission reduction through physical or chemical treatments and dilution through ventilation and air purification. While most solutions involve dilution through ventilation, increased interest in the scientific literature (Wolverton et al, 1989: Godish and Guindon, 1989) as well as in the popular media has been given to the use of plants to purify air in buildings . Most studies however, have been conducted in the laboratory (Levin J, 1992: Godish T and Guindon C, 1989) and are difficult to extrapolate to real life situations (Wolverton et al, 1989: Godish and Guindon, 1989).
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Potted-plant/growth media interactions and capacities for removal of volatiles from indoor air
  • Jan 2003
  • 441-445
  • Wood R A Orwell
  • R L Tarran
  • J Torpy
  • F Burchett
Wood R.A, Orwell R.L, Tarran J., Torpy F, and Burchett M. 2003. Potted-plant/growth media interactions and capacities for removal of volatiles from indoor air. In: Proceedings of Health Buildings 2003-HB2003, Singapore, 1, pp. 441-445.
Can plants help clean up the indoor air?
  • Jan 1992
  • 10-11
  • Hbi
HBI. 1992. Can plants help clean up the indoor air?, Healthy Buildings International Magazine, 2(1), 10-11.