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A Pilot Study of the Effectiveness of Indoor Plants for Removal of Volatile Organic Compounds in Indoor Air in a Seven-Story Office Building

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Abstract

The Paharpur Business Centre and Software Technology Incubator Park (PBC) is a 7 story, 50,400 ft² office building located near Nehru Place in New Delhi India. The occupancy of the building at full normal operations is about 500 people. The building management philosophy embodies innovation in energy efficiency while providing full service and a comfortable, safe, healthy environment to the occupants. Provision of excellent Indoor Air Quality (IAQ) is an expressed goal of the facility, and the management has gone to great lengths to achieve it. This is particularly challenging in New Delhi, where ambient urban pollution levels rank among the worst on the planet. The approach to provide good IAQ in the building includes a range of technical elements: air washing and filtration of ventilation intake air from rooftop air handler, the use of an enclosed rooftop greenhouse with a high density of potted plants as a bio-filtration system, dedicated secondary HVAC/air handling units on each floor with re-circulating high efficiency filtration and UVC treatment of the heat exchanger coils, additional potted plants for bio-filtration on each floor, and a final exhaust via the restrooms located at each floor. The conditioned building exhaust air is passed through an energy recovery wheel and chemisorbent cartridge, transferring some heat to the incoming air to increase the HVAC energy efficiency. The management uses 'green' cleaning products exclusively in the building. Flooring is a combination of stone, tile and 'zero VOC' carpeting. Wood trim and finish appears to be primarily of solid sawn materials, with very little evidence of composite wood products. Furniture is likewise in large proportion constructed from solid wood materials. The overall impression is that of a very clean and well-kept facility. Surfaces are polished to a high sheen, probably with wax products. There was an odor of urinal cake in the restrooms. Smoking is not allowed in the building. The plants used in the rooftop greenhouse and on the floors were made up of a number of species selected for the following functions: daytime metabolic carbon dioxide (CO) absorption, nighttime metabolic CO absorption, and volatile organic compound (VOC) and inorganic gas absorption/removal for air cleaning. The building contains a reported 910 indoor plants. Daytime metabolic species reported by the PBC include Areca Palm, Oxycardium, Rubber Plant, and Ficus alii totaling 188 plants (21%). The single nighttime metabolic species is the Sansevieria with a total of 28 plants (3%). The 'air cleaning' plant species reported by the PBC include the Money Plant, Aglaonema, Dracaena Warneckii, Bamboo Palm, and Raphis Palm with a total of 694 plants (76%). The plants in the greenhouse (Areca Palm, Rubber Plant, Ficus alii, Bamboo Palm, and Raphis Palm) numbering 161 (18%) of those in the building are grown hydroponically, with the room air blown by fan across the plant root zones. The plants on the building floors are grown in pots and are located on floors 1-6. We conducted a one-day monitoring session in the PBC on January 1, 2010. The date of the study was based on availability of the measurement equipment that the researchers had shipped from Lawrence Berkeley National Lab in the U.S.A. The study date was not optimal because a large proportion of the regular building occupants were not present being New Year's Day. An estimated 40 people were present in the building all day during January 1. This being said, the building systems were in normal operations, including the air handlers and other HVAC components. The study was focused primarily on measurements in the Greenhouse and 3rd and 5th floor environments as well as rooftop outdoors. Measurements included a set of volatile organic compounds (VOCs) and aldehydes, with a more limited set of observations of indoor and outdoor particulate and carbon dioxide concentrations. Continuous measurements of Temperature (T) and relative humidity (RH) were made selected indoor and outdoor locations.
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Title:
A Pilot Study of the Effectiveness of Indoor Plants for Removal of Volatile Organic Compounds in
Indoor Air in a Seven-Story Office Building
Author:
Apte, Michael G.
Publication Date:
07-13-2010
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http://escholarship.org/uc/item/226181pq
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1
A Pilot Study of the Effectiveness of Indoor Plants for Removal of Volatile
Organic Compounds in Indoor Air in a Seven-Story Office Building
Michael G. Apte1 and Joshua S. Apte2
1Lawrence Berkeley National Laboratory
Environmental Energy Technologies Division
Indoor Environment Department
Berkeley, CA 94720
2Energy Resources Group
University of California, Berkeley
Berkeley, CA 94720
April 27 2010
This work was sponsored by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office
of Building Technology, State, and Community Programs, of the U.S. Department of Energy under
Contract No. DE-AC02-05CH11231. Its contents are solely the responsibility of the authors and do not
necessarily represent the official views of the US DOE.
2
Introduction
The Paharpur Business Centre and Software Technology Incubator Park (PBC) is a 7
story, 50,400 ft2 office building located near Nehru Place in New Delhi India. The
occupancy of the building at full normal operations is about 500 people. The building
management philosophy embodies innovation in energy efficiency while providing full
service and a comfortable, safe, healthy environment to the occupants. Provision of
excellent Indoor Air Quality (IAQ) is an expressed goal of the facility, and the
management has gone to great lengths to achieve it. This is particularly challenging in
New Delhi, where ambient urban pollution levels rank among the worst on the planet.
The approach to provide good IAQ in the building includes a range of technical elements:
air washing and filtration of ventilation intake air from rooftop air handler, the use of an
enclosed rooftop greenhouse with a high density of potted plants as a bio-filtration
system, dedicated secondary HVAC/air handling units on each floor with re-circulating
high efficiency filtration and UVC treatment of the heat exchanger coils, additional
potted plants for bio-filtration on each floor, and a final exhaust via the restrooms located
at each floor. The conditioned building exhaust air is passed through an energy recovery
wheel and chemisorbent cartridge, transferring some heat to the incoming air to increase
the HVAC energy efficiency. The management uses “green” cleaning products
exclusively in the building. Flooring is a combination of stone, tile and “zero VOC”
carpeting. Wood trim and finish appears to be primarily of solid sawn materials, with
very little evidence of composite wood products. Furniture is likewise in large proportion
constructed from solid wood materials. The overall impression is that of a very clean and
well-kept facility. Surfaces are polished to a high sheen, probably with wax products.
There was an odor of urinal cake in the restrooms. Smoking is not allowed in the
building.
The plants used in the rooftop greenhouse and on the floors were made up of a number of
species selected for the following functions: daytime metabolic carbon dioxide (CO2)
absorption, nighttime metabolic CO2 absorption, and volatile organic compound (VOC)
and inorganic gas absorption/removal for air cleaning. The building contains a reported
910 indoor plants. Daytime metabolic species reported by the PBC include Areca Palm,
Oxycardium, Rubber Plant, and Ficus alii totaling 188 plants (21%). The single
nighttime metabolic species is the Sansevieria with a total of 28 plants (3%). The “air
cleaning” plant species reported by the PBC include the Money Plant, Aglaonema,
Dracaena Warneckii, Bamboo Palm, and Raphis Palm with a total of 694 plants (76%).
The plants in the greenhouse (Areca Palm, Rubber Plant, Ficus alii, Bamboo Palm, and
Raphis Palm) numbering 161 (18%) of those in the building are grown hydroponically,
with the room air blown by fan across the plant root zones. The plants on the building
floors are grown in pots and are located on floors 1-6.
We conducted a one-day monitoring session in the PBC on January 1, 2010. The date of
the study was based on availability of the measurement equipment that the researchers
had shipped from Lawrence Berkeley National Lab in the U.S.A. The study date was not
3
optimal because a large proportion of the regular building occupants were not present
being New Year’s Day. An estimated 40 people were present in the building all day
during January 1. This being said, the building systems were in normal operations,
including the air handlers and other HVAC components. The study was focused
primarily on measurements in the Greenhouse and 3rd and 5th floor environments as well
as rooftop outdoors. Measurements included a set of volatile organic compounds (VOCs)
and aldehydes, with a more limited set of observations of indoor and outdoor particulate
and carbon dioxide concentrations. Continuous measurements of Temperature (T) and
relative humidity (RH) were made selected indoor and outdoor locations.
Methods
Air sampling stations were set up in the Greenhouse, Room 510, Room 311, the 5th and
3rd floor air handler intakes, the building rooftop HVAC exhaust, and an ambient location
on the roof near the HVAC intake. VOC and aldehyde samples were collected at least
once at all of these locations. Both supply and return registers were sampled in rooms
510 and 311. As were a greenhouse inlet register from the air washer and outlet register
ducted to the building’s floor level.
Air samples for VOCs were collected and analyzed following the U.S. Environmental
Protection Agency (USEPA) Method TO-17 (USEPA, 1999a). Integrated air samples
with a total volume of approximately 2 L were collected at the sites, at a flow rate of 70
cc/min onto preconditioned multibed sorbent tubes containing Tenax-TA backed with a
section of Carbosieve. The VOCs were desorbed and analyzed by thermodesorption into
a cooled injection system and resolved by gas chromatography. The target chemicals,
listed in Table 1, were qualitatively identified on the basis of the mass spectral library
search, followed by comparison to reference standards. Target chemicals were quantified
using multipoint calibrations developed with pure standards and referenced to an internal
standard. Sampling was conducted using Masterflex L/S HV-07553-80 peristaltic pumps
assembled with quad Masterflex L/S Standard HV-07017-20 pump heads.
Concentrations of formaldehyde, acetaldehyde, and acetone were determined following
U.S. Environmental Protection Agency (USEPA) Method TO-11a (USEPA, 1999b).
Integrated samples (60 L) were collected by drawing air through silica gel cartridges
coated with 2,4-dinitrophenylhydrazine at a flow rate of 1 Lpm. Samples utilized an
ozone scrubber cartridge installed upstream from the sample cartridge. Sample cartridges
were eluted with 2 mL of high purity acetonitrile and analyzed by high-performance
liquid chromatography (HPLC) with UV detection and quantified with a multipoint
calibration for each derivitized target aldehyde. Sampling was conducted using
Masterflex L/S HV-07553-71 peristaltic pumps assembled with dual Masterflex L/S
Standard HV-07016-20 pump heads.
Continuous measurements of PM2.5 using TSI Dustrak model 8520 monitors were made
in Room 510 and at the rooftop-sampling site from about 13:30 to 16:30 of the sampling
day. The indoor particle monitor was located on a desk in room 510 and the outdoor
monitor was located on a surface elevated above the roof deck.
4
Carbon dioxide spot measurements of about 10-minute duration were made throughout
the building during the afternoon using a portable data logging real-time infrared monitor
(PP Systems model EGM-4A).
Temperature and RH were monitored in the Greenhouse, room 510 and room 311 using
Onset model HOBO U12-011 data loggers (Pocasset MA) at one-minute recording rates.
Outdoor T and RH were not monitored.
Results
VOCsandAldehydes
The measured VOC concentrations as well as their limits of quantitation (LOQ) by the
measurement methods are shown in Table 2. Figures 1-6 show bar graphs of these
VOCs. Unless otherwise shown, all measured compounds were above the minimum
detection level, but not all measurements were above the LOQ. Those measurements with
concentrations below the LOQ should be considered approximations. These air
contaminants are organized by possible source categories including: carbonyl compounds
that can be odorous or irritating; compounds that are often emitted by building cleaning
products; those associated with bathroom products; those often found emitted from office
products, supplies, materials, occupants, and in ambient air; those found from plant and
wood materials as well as some cleaning products; and finally plasticizers commonly
emitted from vinyl and other flexible or resilient plastic products. The groupings in this
table are for convenience; many of the listed compounds have multiple sources so the
attribution provided may be erroneous.
CarbonylCompounds
The carbonyl compounds include formaldehyde that can be emitted from composite
wood materials, adhesives, and indoor chemical reactions; acetaldehyde from building
materials and indoor chemistry; acetone from cleaners and other solvents. Benzaldehyde
sources can include plastics, dyes, fruits, and perfumes. Hexanal, nonanal, and octanal
can be emitted from engineered wood products. For many of these compounds, outdoor
air can also be a major source. Formaldehyde and acetone were the most abundant
carbonyl compounds observed in the PBC. For context, the California 8-h and chronic
non-cancer reference exposure level (REL) for formaldehyde is 9 µg m-3 and the acute
REL is 55 µg m-3 (OEHHA 2008). The 60 minute average formaldehyde concentrations
observed in the PBC exceeded the REL by up to a factor of three. Acetone has low
toxicity and the observed levels were orders of magnitude lower than concentrations of
health concern.
Hexanal, nonanal, and octanal are odorous compounds at low concentrations; odor
thresholds established for them are 0.33 ppb, 0.53 ppb, and 0.17 ppb, respectively
(Cometto-Muñiz and Abraham, 2010). Average concentrations observed within the PBC
building were 3.8±0.8 ppb, 3.5±0.6 ppb, and 1.4±0.2 ppb, for these compounds,
respectively, roughly ten times higher than the odor thresholds. Concentrations of these
compounds in the supply air from the greenhouse were substantially lower, although still
5
in excess of the odor thresholds. The concentration of hexanal and nonanal roughly
doubled the ambient concentrations as the outside air passed through the greenhouse.
Octanal concentrations were roughly similar in the ambient air and in the air exiting the
greenhouse.
CleaningSolventCompounds
Concentrations of benzene, d-limonene, n-hexane, naphthalene and toluene all increased
in the greenhouse air in either the AM or PM measurements. The measured levels of
these compounds were far below any health relevant standards, although naphthalene
concentrations reached close to 50% of the California REL of 9 µg m-3 (OEHHA 2008).
The concentrations of these compounds were generally somewhat higher indoors relative
to the greenhouse concentrations. The concentration of toluene in the building exhaust
was 120 µg m-3, more than double the highest level measured indoors, suggesting a
possible toluene source in the restrooms. The cleaning compound 2-butoxyethanol was
slightly higher indoors, but at very low concentrations. Similar for trichloroethylene that
was observed at extremely low levels indoors.
BathroomProducts
1,4-dichlorobenzene is a common deodorizer and is the primary component in urinal
cake. The concentration of this compound appears to increase as the ventilation air
travels through the building; about 5-6 µg m-3 in the greenhouse exit air, about 20 - 25
µg m-3 on floor 3, and 50 – 65 µg m-3 on floor 5. The levels increased dramatically in the
building exit stream, reaching 170 µg m-3. It is not a surprise that this compound is
measured in the exhaust of the building since this air stream flows through the restrooms.
It appears that there may be more entrainment of bathroom air into the fifth floor than on
the third floor. 1,4 –dichlorobenzene has a chronic REL of 800 µg m-3, substantially
higher than the highest level observed in this study (OEHHA, 2008).
Officeproducts,Supplies,Materials,Occupants,Ambientair
The compounds listed in this category have many sources, including outdoor air. For the
most part there was little difference across the building spaces for these compounds, and
little difference from the ambient air measurement. The single exception to this
observation is methylene chloride that appears to increase by about a factor of ten
indoors. It is possible that this compound is in use as a cleaning solvent, or it may be
present in computer equipment or other supplies. Methylene chloride is also used as a
spot remover in dry cleaning processes and may be carried into the building on occupant
clothing. The levels of this compound were low relative to health standards (400 µg m-3,
24 h, OEHHA 2001).
Plantmaterials,woodmaterials,cleaners
A small increase of a-pinene was observed in the building, particularly on the 5th floor.
The source of this compound could be wood products, the indoor plants, cleaning
supplies, or air freshener. The concentration of this compound was extremely low.
Plasticizers
Only trace levels of the plasticizers TXIB (2,2,4-trimethylpentanediol diisobutyrate) and
diethylphtalate were observed in the building. TXIB is used to increase the flexibility of
vinyl products. The measurements likely confirm that very little of these products are
present in the PBC. Similarly, diethylphtalate is a compound used to soften plastics.
These measurements likely confirm that very little of these products are present in the
PBC, however there is a suggestion of a source in the building.
ParticleConcentrations
Indoor and outdoor particle concentrations (PM2.5, particles less than 2.5 micrometers in
aerodynamic diameter) measured in the afternoon of January 1 are shown in Figure 7.
Average (±standard deviation) PM2.5 concentrations were 380±49 and 26±8 µg m-3 at the
outdoor and indoor measurement sites, respectively. This translates to an indoor/outdoor
ratio of 6.8%.
Temperature,RelativeHumidityandIndoorCarbonDioxideConcentrations
Table 3 lists indoor and outdoor T and RH concentrations and CO2 10 minute average
spot measurements. Greenhouse temperatures were lower and RH levels were higher
throughout the study day.
Ambient CO2 concentration on the roof was 380 ppm. The outlet of the greenhouse was
slightly higher at 385 ppm. Fifth floor concentrations at the AHU return was 500 ppm,
while the 3rd floor concentration was about 600 ppm. It was not possible to discern the
amount by which the plants in the building were lowering the CO2 concentration,
primarily because of the low occupancy on January 1.
Discussion
AreplantsreducingindoorVOCandaldehydes?
Table4showsrelativedifferencesinVOCandaldehydeconcentrationsatdifferent
ointswithinthePBCasairflowsthroughthebuilding.Therelativeconcentration
ifferencespercentagesarecalculatedasfollows.
p
d
= Upstream Concentration - Downstream Concentration
6
Relative Difference Upstream Concentration
100
NotethatforcompoundswheremeasurementswerebelowtheLOQtherelative
differencemaybeanartifactofimprecisionofmeasurementratherthanareflection
ofrealdifferences.Thesevaluesshouldbeinterpretedcarefully.InTable4the
compoundswhichdisplayrelativereductionsbetweentwozonesareshadedatan
olor,whilethosewithrelativeincreaseoffactorsoftensareshadedlightgreen,c
andthosewithrelativeincreasesbyfactorsof100areshadedred.
TheHVACinlettothebuildingwhichincludesanairwasherandfiltrationshoweda
reductionofallmeasuredVOCsandaldehydeswiththeexceptionofoctanal,1,4‐
dichlorobenze,decamethylpentasiloxane,phenol,TXIBanddiethylpthalate.The
reductionswererangedfrom4%(chloroform)to100%for2‐butoxyethanol,d‐
limonene,trichloroethylene,anda‐pinene.Theplasticizerconcentrationsincreased
7
140%(TXIB)and320%(diethylpthalate)astheairmovedfromoutsideintothe
greenhouse.
VOCconcentrationsallincreased(exceptoctanal,‐5%,TXIB‐53%,and
diethlylpthalate‐80%)astheairwastransmittedthroughthegreenhouse.The
concentrationoftheodorouscompoundshexanalandnonanalincreasedby68%
and110%,respectivelyinthegreenhouse.Mostothercompoundsshowedmodest
ncreasesontheorderof10sofpercentagepoints,althoughstyreneconcentrationsi
increasedbyalmostafactorof7inthegreenhouse.
Withonlyafewexceptions(relativelysmallreductionsofbenzaldehyde,benzene,
carbontetrachloride,andethylbenzene),VOCandaldehydeconcentrations
increasedastheventilationairmovedfromthegreenhouseintotheoccupied
buildingspaces.Increasesbetweentheaverageindoorconcentrationsandthe
greenhouseairexitrangedfrom6%fortoluenetoafactorof120forthecleaning
solvent2‐butoxyethanol.Thecleaningsolventd‐limoneneincreasedbyafactorof
56,methylenechlorideincreasedbyafactorof11,anda‐pinenebyafactorof64.
Diethylpthalateincreasedbyafactorof21.Odorouscompoundshexanal,nonanal,
andoctanalallincreasedbyfactorsoftwotofour,asdidtheirritatingand
arcinogeniccompoundformaldehyde.Thedeodorant1,4‐dichlorobenzenec
concentrationincreasedbyoverafactorofsix.
TheconcentrationoftheVOCsandaldehydesintheHVACexhauststreamwasin
onlyasinglecaselowerthantheincomingair(octanal),whereitwaszerointhe
exhaust.D‐limonenewas19foldhigherintheexhaustthantheintake,1,4‐
dichlorobenzenwas76foldhigher,anddiethylpthalateincreased17fold.
Concentrationsintheexhaustvs.greenhousetendedtobehigherthanthe
comparisontotheambientair–thisisduetheobserveddecreaseattheintake
relativetothegreenhouse–possiblythebenefitoftheairwasher.Overall,exhaust
oncentrationsexceededthatsuppliedtothezonescontainingplantsbysmalltoc
largemultiples.
Theconceptthatthebuildingairisscrubbedcleanofgaseousaircontaminantsby
theplantsisnotsupportedbythedata.Thisbeingsaid,itisnotknownwhatthe
buildingIAQwouldbewithouttheplants.
ComparisonofVOCandAldehydeConcentrationwithotherOfficeBuildings
Table5providesacomparisonbetweenthemeasuredindoorVOCandaldehyde
concentrationsinthePBCandthosemeasuredinasurveyofofficebuildingsinthe
UnitedStates(U.S.).From1994to1998theU.S.EnvironmentalProtectionAgency
(EPA)conductedtheBuildingAssessmentandSurveyEvaluation(BASE)Studyof
100randomlyselectedofficebuildingsinthecontinentalU.S.(Wombleetal1996).
ThedatainTable5aresummarystatisticsofmeasurementstakenfromtheBASE
study(ApteandErdmann,2002).NotethatnotalloftheVOCsmeasuredinthePBC
werestudiedintheBASEstudy,andvise‐versa.TheBASEstudydidnotmeasureall
ofthelistedcompoundsinall100buildingsascanbeseenfromtheTable.
8
CompoundsforwhichthePBChadmorethatafactoroftwogreaterindoor
concentrationsthantheBASEStudymeanare1,4‐dichlorobenzene,methylene
chloride(alsogreaterthantheBASEStudymaximum),andTXIB.Themeasured
BCformaldehydeandacetaldehydelevelswerebothabovethemeanBASEStudyP
levelsbymorethanonestandarddeviation.
CompoundsforwhichthePBChadonehalforlessoftheconcentrationoftheBASE
Studyindoorconcentrationsincluded2‐butoxyethanol,acetone,d‐limonene,
henol,andstyrene.Both2‐butoxyethanolandd‐limonenearecleaningagentsthatp
maybeusedlessfrequentlyinthePBCthanintheU.S.officebuildings.
Thecompoundmeasuredthatisofgreatestconcernisformaldehyde,asdiscussed
above,whichhasan8‐hraverageRELof9µgm‐3.Theaverageacrossthemeasured
spacesinFloors5and3was28±1.4µgm‐3.However,theobservedformaldehyde
oncentrationsfallwithinlevelsthathavebeenrecordedinU.S.officebuildings(3.4c
to45µgm‐3).
Theobservedlevelsofodorouscompoundshexanal,nonanal,andoctanalmay
detractfromperceivedairqualityinthePBC,astheobservedconcentrationsexceed
ocumentodorthresholds.Howeverthelevelsmaynotbehighenoughtobed
irritatingtooccupants.
Thepresenceof1,4‐dichlorobenzeneintheambientandgreenhouseairsuggests
thatsomeshortcircuitingofventilationexhaustbackintothebuilding.Itmayalso
bepossiblethatsomeleakageacrosstheheatrecoverywheelisslightly
contaminatingthefreshintakeair.
MeasuredParticleConcentrations
TheremovalofambientparticulatematterbythePBCrooftopairhandler,the
particlelossmechanismsintheairtransitthroughgreenhouseandductingintothe
building,andthere‐circulatingfiltrationofairbythefloorlevelAHUsappearstobe
rathersuccessful.IndoorPM2.5wasreducedto26±8 µg m-3 7%ofoutdoorlevels.
TherearenoindoorstandardsforPM2.5,buttheWorldHealthOrganizationhasset
theoutdoor24hourstandardsat25µg/m3,andtheannualPM2.5standardat10
µg/m3(WHO2000).ConsideringtheextremelyhighoutdoorPM2.5levelsinNew
Delhi,theprotectiveenvironmentprovidedbythePBCisphenomenal.
OtherAirContaminantsofConcern
Thisone‐daystudydidnotmeasureallpossibleaircontaminantsinthePBCor
surroundingoutdoorair.Ozoneisanimportantaircontaminantthatwasnot
measured,thatmayhaveabearingonIAQinthebuilding.OnJanuary1theozone
levelintheambientairwaslikelyaroundit’slowestfortheyearasitsformationis
dependentonradiationfromthesun,anditvarieswiththeseasons.However,
duringothertimesoftheyear,ozoneentrainedintothebuildingcouldhavea
9
significantimpactonIAQasitreactswithd‐limonene,a‐pinene,andotheralkene
compounds.Futureworkshouldincludeastudyofozoneentryintothebuilding.
Conclusions
IndoorenvironmentalqualityinthePBC,asmeasuredbytheVOCandaldehyde
speciesmeasuredinthisstudy,isverysimilartothatmeasuredinmanyoffice
uildingsintheUnitedStates.Giventheextremeairpollutionlevelsintheoutdoorb
environmentofNewDelhi,thisisanachievement.
Thepurposeofthisstudywastoinvestigatethebenefitsofusingindoorplantsto
cleantheofficebuildingair.Havingdonethis,thereappearstobenostrong
evidencethattheplantsplayaspecialroleincleaningthePBCair.Theairwasher
andfiltrationarrayattheintakeofthebuilding’sHVACsystemappearsto
substantiallyreduceincomingaircontaminants.Oncetheventilationairentersthe
building,theconcentrationofcommonVOCsandaldehydesappeartorise
incrementallyuntiltheairisexhausted.ThekeycontaminantofconcerninthePBC
isformaldehyde.Thedeodorantusedintherestroomsraisesindoorlevelsof1,4‐
dichlorobenznetoatypicallyhighconcentrations.Methylenechlorideappearsto
haveanabundantsourceinthePBC.
Acknowledgements
This work was sponsored by the Assistant Secretary for Energy Efficiency and
Renewable Energy, Office of Building Technology, State, and Community Programs, of
the U.S.Department of Energy under Contract No. DE-AC02-05CH11231. Its contents
are solely the responsibility of the authors and do not necessarily represent the official
views of the US DOE. The authors would like to thank Randy Maddalena and William
Fisk for their reviews of this paper, Marion Russell for analysis of the VOC samples, and
Doug Sullivan for organization and shipping of the equipment used in this project.
References
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Concentrations, VOCs, and Environmental Susceptibilities with Mucous Membrane
and Lower Respiratory Sick Building Syndrome Symptoms in the BASE Study:
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Laboratory, University of California, Berkeley, CA 94720.
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Carbonyl Compounds in Air; ASTM Test Method D-5197-92; American Society for
Testing and Materials (ASTM):West Conshohocken, PA, 1992.
Cometto-Muñiz JE, Abraham MH. 2010. Odor Detection by Humans of Lineal Aliphatic
Aldehydes and Helional as Gauged by Dose-Response Functions,” Chem. Senses.
Online publication ahead of print.
OEHHA. 2001. Chronic Toxicity Summary – Methylene Chloride, Office of
Environmental Health Hazards Assessment, California Environmental Protection
10
Agency, Sacramento CA. http://www.oehha.org/air/chronic_rels/AllChrels.html
OEHHA. 2008. Chronic Toxicity Summary – Formaldehyde, Office of Environmental
Health Hazards Assessment, California Environmental Protection Agency,
Sacramento CA. http://www.oehha.org/air/chronic_rels/AllChrels.html
USEPA. 1999a Determination of Volatile Organic Compounds in Ambient Air Using
Active Sampling onto Sorbent Tubes: Compendium Method TO-17; Office of
Research and Development, U.S. Environmental Protection Agency: Research
Triangle Park, NC, 1996.
USEPA. 1999b Determination of Formaldehyde in Ambient Air Using Adsorbent
Cartridge Followed by High Performance Liquid Chromatography (HPLC) [Active
Sampling Methodology]: Compendium Method TO-11A; Office of Research and
Development, U.S. Environmental Protection Agency: Research Triangle Park, NC,
1996.
WombleSE,RoncaEL,GirmanJR,etal.1996.“DevelopingBaselineInformationon
BuildingsandIndoorAirQuality(Base’95),”InIAQ96/PathstoBetterBuilding
Environments/HealthSymptomsinBuildingOccupants,AmericanSocietyof
HeatingRefrigerationandAir‐conditioningEngineers,Atlanta.
WHO. 2000. Air quality guidelines for Europe, 2nd ed. Copenhagen, World Health
Organization Regional Office for Europe, 2000 (WHO Regional Publications,
European Series No. 91).
11
Tables
Table 1. Target List of Volatile Organic Chemicals
analysis
Chemical Class CAS BP method
Phenol alcohol 108-95-2 182 TD-GC/MS
Formaldehde aldehyde 50-00-0 -19 DNPH/HPLC
Acetaldehyde aldehyde 75-07-0 20 DNPH/HPLC
n-Hexanal aldehyde 66-25-1 128 TD-GC/MS
Octanal aldehyde 124-13-0 174 TD-GC/MS
Benzaldehyde aldehyde 100-52-7 179 TD-GC/MS
Nonanal aldehyde 124-19-6 195 TD-GC/MS
Decanal aldehyde 112-31-2 209 TD-GC/MS
n-Hexane alkane 110-54-3 69 TD-GC/MS
Benzene aromatic 71-43-2 80 TD-GC/MS
Toluene aromatic 108-88-3 111 TD-GC/MS
Ethylbenzene aromatic 100-41-4 136 TD-GC/MS
m-Xylene aromatic 108-38-3 139 TD-GC/MS
p-Xylene aromatic 106-42-3 139 TD-GC/MS
o-Xylene aromatic 95-47-6 143 TD-GC/MS
Styrene aromatic 100-42-5 145 TD-GC/MS
Naphthalene aromatic 91-20-3 218 TD-GC/MS
1,4-dichlorobenzene
Cl
Aromatic 106-46-7 174 TD-GC/MS
TXIBa ester 6846-50-0 280 TD-GC/MS
Diethylphthalate ester 84-66-2 298 TD-GC/MS
2-Butoxyethanol
glycol
ether 111-76-2 171 TD-GC/MS
Methylene Chloride halo 75-09-2 40 TD-GC/MS
Chloroform halo 67-66-3 62 TD-GC/MS
Carbon
Tetrachloride halo 56-23-5 77 TD-GC/MS
Trichloroethylene halo 79-01-6 87 TD-GC/MS
Tetrachloroethylene halo 127-18-4 121 TD-GC/MS
Acetone ketone 67-64-1 56 DNPH/HPLC
D-5 Siloxane misc. 541-02-6 210 TD-GC/MS
α-Pinene terpene 7785-70-8 155 TD-GC/MS
d-Limonene terpene 5989-27-5 177 TD-GC/MS
a 2,2,4-Trimethylpentanediol diisobutyrate
Table 2. Measured Volatile Organic Compounds (VOCs) and Aldehyde concentrations indoors and outdoors at the PBC. The limits
of quantitation (LOQ) for the measurements of these compounds are also provided.
VOCs
Measured (µg/m3) LOQc Ambient GH
In
GH Out
(AM)
GH Out
(PM)
Rm 311
Supply Rm.510
Supply
Rm.311
Rtn.
Rm 510
Rtn.
Flr. 3
AHU Rtn. Flr. 5
AHU Rtn. Bld.
Exh.
Carbonyl
Acetaldehyde 0.2 6.9 4.4 4.1 6.0 12 13 12 13 12 11 11
Acetone 0.2 10 6.8 6.5 9.7 22 26 24 26 23 22 18
Benzaldehyde 0.7 2.2 2.6 3.3 3.6 2.3 2.5 2.1 2.3 2.0 2.0 2.5
Formaldehyde 0.4 6.2 4.5 3.9 8.5 27 27 30 29 29 25 20
Hexanal 2.4 0.8 0.5 1.1 0.6 4.5 4.1 4.6 3.7 3.2 2.6 3.4
Nonanal 2.1 1.2 0.6 1.4 1.1 4.3
1.6
Cleaning solvents
3.8 3.7 3.5 3.1 2.6 2.2
Octanal 2.4 0.3 0.3 0.2 0.3 1.6 1.6 1.5 1.3 1.2 ND
2-butoxyethanol 1.7 1.3 ND ND ND 1.5 2.7 2.0 2.4 1.4 1.5 1.5
Benzene 4.8 6.6 4.6 5.1 11 5.9 6.9 6.5 6.1 6.4 4.7 12
d-limonene 0.4 0.1 0.0 0.0 0.2 2.1 13 2.1 11 2.2 4.5 2.9
n-hexane 5.6 4.5 3.2 4.0 9.2 5.7 4.8 6.8 3.5 7.7 3.4 14
Naphthalene 0.5 0.5 0.3 0.3 0.8 4.3 4.2 4.1 4.1 3.2 3.5 3.1
Toluene 0.4 48 18 18 59 41
3
Bathroom products
40 41 34 53 33 120
Trichloroethylene 1.3 0.2 ND ND ND 0. 0.4 0.3 0.3 0.3 0.2 0.6
1,4-dichlorobenzene 0.3 2.2 3.9 4.8 6.0 25 65 23 56 21 49 170
Office products, supplies, materials, occupants, Ambient
Carbon tetrachloride 5.2 0.2 0.4 0.3 0.7 0.6 0.5 0.5 0.5 0.2 0.3 0.6
Chloroform 7.4 0.4 0.4 0.3 0.7 1.5 1.0 1.4 0.8 1.2 0.9 1.3
D5 siloxane 1.2 0.1 0.1 0.1 0.1 0.6 0.8 0.5 0.8 0.5 0.5 0.9
Ethylbenzene 0.4 4.6 2.4 2.2 7.2 5.1 4.5 4.7 4.1 5.5 3.7 11
M/p-xylene 0.4 9.9 4.6 4.3 15 12 10 10 9.1 13 8.1 25
Methylene chloride 4.0 1.3 0.9 1.1 3.0 33 23 36 14 23 19 13
o-xylene 0.5 4.7 2.3 2.1 6.8 5.2 4.5 5.2 4.3 5.7 3.7 11
Phenol 6.7 0.3 0.5 0.9 ND 0.9 1.0 0.9 0.9 0.9 0.8 0.8
Styrene 0.6 0.4 0.0 0.0 0.7 0.8 0.8 0.9 0.8 0.9 0.7 1.5
Tetrachloroethylene 0.6 0.7 0.6 0.5 0.9 1.3 1.3 1.5 1.1 0.9 0.8 2.0
Plant materials, wood materials, cleaners
α -pinene 0.7 0.6 ND ND ND 0.7 2.2 0.7 2.0 0.6 1.2 0.8
Plasticizers
TXIBa 1.4 0.0 0.1 ND ND 0.2 0.1 0.2 0.1 0.2 0.1 0.1
Diethylphthalate 0.4 0.0 0.1 ND ND 0.4 0.4 0.5 0.4 0.5 0.3 0.4
a 2,2,4-trimethylpentanediol diisobutyrate, bdecamethylcyclopentasiloxane; cLimit of Quantitation
12
ND = not detected or less than minimum detection level
13
Table 3. Measured Carbon Dioxide (CO2), Temperature (T), and Relative Humidity (RH)
Location Start Stop CO2 (ppm) T (ºC) RH(%)
Ambient PM monitoring loc
on roof 15:45 15:56 381
Greenhouse inlet 16:34 16:47 385 17.5±0.1 72±0.6
Greenhouse outlet 16:01 16:30 391 17.2±0.2 71±0.5
Rm 311 15:18 15:28 643 22.9±0.1 48±0.5
AHU 3rd floor 15:31 15:41 601 23.1±0.0 48±0.5
Rm 506 15:04 15:15 552 24.3±0.1 44±0.1
AHU 5th floor 14:52 15:02 495 24.3±0.0 44±0.1
Building exhuast 16:52 17:03 476
All Day
Greenhouse 19±3.6 66±9.9
RM 506 23±1.4 47±3.8
RM 311 22±1.0 50±3.1
Table4.Relativedifferences(percent)betweenVOCandaldehydeconcentrationsbetweendifferentPBCHVACdomains
Compound/locationa GHin vs
OUT
GHin
Gho
vs
ut
FLR5 vs
GHout
FL3 vs
GHout
Indoor vs
GHout
Exh vs
GHi
n
Exh vs
OUT
(%) (%)(%)(%)(%)(%)(%)
Carbonyl
acetaldehyde -36 14 140 1 140 140 54
acetone -33 19 210 190 200 170 76
benzaldehyde 19 32 -34 -38 -36 -4 14
formaldehyde -28 38 330 370 350 340 210
hexanal -37 68 310 390 350 580 330
nonanal -50 110 170 200 180 260 80
octanal 8 -5 400 420 410 -100 -100
Cleaning solvents
2-butoxyethanol -100 - 14000 10000 12000 - 19
benzene -30 73 -27 -22 -24 170 86
d-limonene -100 - 9200 1900 5600 - 1900
n-hexane -30 110 -41 2 -20 340 210
naphthalene -31 80 580 560 570 860 560
toluene -63 110 -7 18 6 570 150
trichloroethylene -100 - - - - - 210
Bathroom products
1,4-dichlorobenzene 76 40 950 330 640 4300 7600
Office products, supplies, materials, occupants, Ambient
carbon tetrachloride 71 19 -14 -13 -14 39 140
chloroform -4 37 80 180 130 260 250
decamethylcyclopentasiloxane 61 -53 940 660 800 480 830
ethylbenzene -48 96 -13 8 -2 350 130
m/p-xylene -54 110 -5 21 8 450 160
methylene chloride -32 130 830 1400 1100 1400 920
o-xylene -52 98 -7 20 7 370 120
phenol 53 -3 100 100 100 83 180
styrene -88 680 110 130 120 3000 260
tetrachloroethylene -24 26 55 79 67 270 180
Plant materials, wood materials, cleaners
a-pinene -100 - 9400 3300 6400 - 42
Plasticizers
TXIB 0
b 14 -53 159 300 230 50 260
diethylphthalate 320 -80 1900 2300 2100 340 1700
14
aLocations:GHin=Inlettogreenhouse;GHout=outletfromgreenhouse;Indoor=averageofallindoorlocations;Exh=building
exhaust.;b2,2,4-Trimethylpentanediol diisobutyrate
Shading code: Tan = negative/relative reduction of concentration; light green = rel. increases by factors of ten; red = rel. increases by
factors of 100
15
Table 5. Comparison of select PBC VOC and Aldehyde measurements to those in the
100 Building U.S. EPA BASE Study.
PBC Indoors U.S. EPA BASE Study Indoor-outdoor Concentrations
Mean Std Dev Mean Std Dev Median Minimum Maximum # of BASE
Compound (µg m-3) (µg m-3) (µg m-3) (µg m-3) (µg m-3) (µg m-3) (µg m-3) Buildings
1,4-dichlorobenzene 40 19 3.1 8.0 0.6 0.2 49.6 100
2-butoxyethanol 1.9 0.53 12.3 19.2 6.4 0.1 88.6 41
a-pinene 1.2 0.70 1.1 1.1 0.6 0.2 7.9 100
acetaldehyde 12 0.70 7.9 3.8 7.3 2.0 17.4 86
acetone 24 1.8 55.4 33.7 45.8 14.5 221.7 87
benzene 6.1 0.75 4.9 3.9 3.6 0.9 32.5 100
methylene chloride 25 8.2 2.9 1.7 2.7 1.2 16.2 87
d-limonene 5.9 5.1 11.3 17.0 6.2 0.3 130.3 100
ethylbenzene 4.6 0.65 2.7 2.2 1.8 0.3 11.5 100
formaldehyde 28 1.9 16.3 8.4 15.0 3.4 45.0 100
hexanal 3.8 0.8 5.4 3.3 4.2 1.2 14.6 41
m & p-xylenes 10 1.6 8.8 8.0 6.2 1.1 39.3 100
n-hexane 5.3 1.8 6.1 13.3 3.6 0.2 100.5 54
naphthalene 3.9 0.44 6.9 23.5 1.1 0.2 181.6 100
nonanal 3.5 0.6 3.6 2.4 3.0 0.8 11.9 54
o-xylene 4.8 0.73 3.1 2.7 2.2 0.4 13.7 100
phenol 0.89 0.08 2.4 2.0 2.0 0.4 8.6 41
styrene 0.83 0.08 1.7 2.2 0.9 0.2 14.3 100
Toluene 20 7.1 17.7 33.0 9.6 2.2 314.8 100
TXIBa 15 0.05 7.2 8.3 3.6 0.2 32.2 41
a2,2,4-Trimethylpentanediol diisobutyrate
Figures
16
Figure 1. Carbonyl compounds measured at the PBC.
17
CleanersandSolvents
0.00
20.00
40.00
60.00
80.00
100.00
120.00
140.00
2butoxyethanol benzene dlimonene nhexane naphthalene toluene trichloroethylene
Compound
V15,Roofoutsideair
VI9,GreenhouseSupply
VI10,Greenhouseout
VI16,GHout
VI1,Rm,311Supply
VI5,Rm.510Supply
VI2,Rm.311Return
VI6,Rm510Return
VI13,Floor3AHURetun
VI11,Floor5AHUReturn
VI17,Bld.Exhaust
Figure 2. Volatile organic compounds associated with cleaning supplies and solvents measured at the PBC.
Figure 3. Volatile organic compounds associated with bathroom deodorizer measured at the PBC.
18
Figure 4. Volatile organic compounds associated with office products, supplies, materials, occupants, ambient air pollution measured
at the PBC.
19
Figure 5. Volatile organic compounds associated with plant materials, wood materials, cleaners measured at the PBC.
20
Figure 6. Volatile organic compounds associated with plasticizers in materials measured at the PBC.
21
Figure 7. Indoor and outdoor (ambient) PM particle concentrations at the PBC.
2.5
22

Supplementary resource (1)

... As part of the manned space program, NASA scientists in the 1980s found that certain indoor plant species and their associated microorganisms effectively removed VOCs in closed systems, purifying the air (Wolverton, 1986). But when indoor plants were tested in situ for their ability to remove VOCs in buildings, the results have ranged from modest to no effect (Apte and Apte, 2010;Kim et al., 2009;Pegas et al., 2012), leaving open the question, whether plants actually represent a viable solution for modulating the concentration of VOCs in a home or office environment. Buildings, in contrast to small sealed chambers, are much more complex systems, often having significant air exchange with the exterior and varying rates of VOC emanation from interior sources, neither of which have been measured in existing in situ studies. ...
... Nevertheless, assuming the air is well mixed, r x is not too high, a is in a similar range to that seen in closed-container experiments, and the experiment was run for long enough, a noticeable reduction would be expected. This was not the case nor has it been in nearly all other in situ studies (Anon, 1992;Apte and Apte, 2010;Dingle et al., 2000;Lim et al., 2009). ...
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... Among the houseplants that can grow under low indoor illumination (300- The target plant, areca palm ( Figure 3), is recognized worldwide as one of the best indoor air purification plants, absorbing CO 2 and producing O 2 to detoxify its surroundings by removing air pollutants such as formaldehyde (CH 2 O), xylene (C 8 H 10 ) and toluene (C 7 H 8 ) [61,62]. Among the houseplants that can grow under low indoor illumination (300-1000 lx), it was selected due to having a high CO 2 reduction effect in previous studies [63,64]. Based on the previous research, areca palm trees can increase O 2 concentrations from 18.56% to 21.33% after 7 h and decrease CO 2 concentrations from 428 ppm to 419 ppm [65]. ...
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... Therefore, this research has shown that inexpensive custom-designed botanical purification system for indoor air quality monitoring and improvement can provide data on the indoor air quality and the positive impact of plants on indoor air pollutants. Although some authors claim that previously conducted studies have failed to confirm the positive impact of plants on the air quality in indoor spaces (Apte & Apte 2010), others sources claim that there is an evident positive impact of certain ornamental plants such as Ficus elastica, Dracaena deremensis and Sansevieria trifasciata ( Husti et al., 2016) on indoor air pollutants. These contrary reports confirm that there is a constant need for a functional and economically affordable botanical system for air purification. ...
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