Front page for deliverables
Project no.
003956
Project acronym
NOMIRACLE
Project title
Novel Methods for Integrated Risk Assessment of
Cumulative Stressors in Europe
Instrument
IP
Thematic Priority
1.1.6.3 ‘Global Change and Ecosystems’
Topic VII.1.1.a, ‘Development of risk assessment
methodologies’
Deliverable reference number and title:
D. 2.2.5 Assessment of the (source-dependent) indoor/outdoor ratios of
volatile organic compounds (VOCs)
Due date of deliverable: April 2007
Actual submission date: April 2007
Start date of project: 1 November 2004
Duration: 5 years
Organisation name of lead contractor for this deliverable: UFZ
Revision: draft
Project co-funded by the European Commission within the Sixth Framework Programme (2002-2006)
Dissemination Level
PU
PP
RE
CO
Public
Restricted to other programme participants (including the Commission Services)
Restricted to a group specified by the consortium (including the Commission Services)
Confidential, only for members of the consortium (including the Commission Services)
x
Authors and their organisation:
Silke Matysik1, Tibor Kohajda1, Martina Rehwagen1, Olf Herbarth1, Otmar
Geiss2, Salvatore Tirendi2, Diana Rembges2,
1
2
Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
Joint Research Centre, Ispra, Italy
Deliverable no:
D.2.2.5
Status: Final
Nature:
Report
Dissemination
level: PU
Date of delivery:
April 30, 2007
Date of publishing:
Reviewed by (period and name): Philipp Mayer (NERI)
Deliverable reference number and title:
D. 2.2.5 Assessment of the (source-dependent) indoor/outdoor ratios of
volatile organic compounds (VOCs)
2
Assessment of the (source-dependent) indoor/outdoor ratios of volatile organic
compounds (VOCs)
Silke Matysik1, Tibor Kohajda1, Martina Rehwagen1 and Olf Herbarth1
Otmar Geiss2, Salvatore Tirendi2, Diana Rembges 2
1
2
Helmholtz-Centre for Environmental Research – UFZ, Leipzig, Germany
Joint Research Centre, Ispra, Italy
List of contents
1
2
2.1
2.2
3
3.1
3.2
3.3
4
4.1
4.2
5
Introducing remarks
Results from a measuring campaign in Leipzig
Indoor/outdoor ratios of relevant VOCs
Source dependence of relevant VOCs
Indoor/outdoor ratios of VOCs in different regions of Europe
Study design
Comparability of data sets
Comparison of indoor/outdoor ratios of VOCs across Europe
Personal risk assessment of VOC uptake based on indoor/outdoor
measurements
Theoretical and measured daily uptake of VOCs
Assessment of personal exposure to VOCs across Europe
Conclusion
3
1 Introducing remarks
The results presented in this report are based on data measured during a campaign in
Leipzig (D) in 2005, during two campaigns in Leipzig under the frame of the NoMiracle
project in 2005 and 2006 and during campaigns of the “Indoor Air Monitoring and
Exposure Assessment Study (Airmex)” of the JCR Ispra in Arnhem (NL) and Athens
(GR). The second campaign in Athens was carried out together with the UFZ in the
NoMiracle project.
2 Results from a measuring campaign in Leipzig
2.1 Indoor/outdoor ratios of relevant VOC
The Leipzig study in 2005 comprised 97 indoor air and 159 outdoor air measurements
using passive sampling (with 3M monitors of the type OVM 3500) of volatile organic
compounds (VOCs). The sampling was performed both inside and outside of 34
kindergartens of Leipzig during one year. In every kindergarten measurements were
performed at least twice at different seasons. During the course of the quantitative analysis
concentrations of 29 VOCs within the groups of alkanes, cycloalkanes, aromatics,
halogenated hydrocarbons and terpenes were determined.
The main results of the indoor and outdoor VOC measurements in 34 kindergartens in
Leipzig 2005 are given in Table 1 which shows selected data for the alkanes hexane and
decane, the aromatics benzene, toluene, ethylbenzene, m-, p-xylene, styrene and o-xylene
and the terpenes -pinene and limonene.
Table1: Main results of the indoor (n=97) and outdoor (n=159) VOC measurements in 34
kindergartens in Leipzig in 2005. Concentrations in µg/m3 .
indoor
Hexane
Decane
Benzene
Toluene
Ethylbenzene
m-, p-Xylene
Styrene
o-Xylene
-Pinene
d-Limonene
29 VOC Sum
outdoor
Hexane
Decane
Benzene
Toluene
Ethylbenzene
m-, p-Xylene
Styrene
o-Xylene
-Pinene
d-Limonene
29 VOC Sum
Average
Max
Min
Median
Stddev.
2.1
4.8
1.5
5.5
1.7
4.2
0.9
1.4
11.9
18.0
107.7
12.5
58.5
3.2
29.0
11.7
29.2
40.3
8.4
152.9
131.3
1206.4
0.5
0.1
0.2
0.3
0.1
0.0
0.0
0.0
0.0
0.1
4.2
1.8
2.1
2.1
4.6
1.1
2.5
0.4
0.9
3.9
5.7
62.9
1.5
8.9
0.6
8.0
1.8
4.8
4.0
1.4
23.0
24.9
147.4
1.2
0.4
1.3
2.4
0.4
1.0
0.0
0.3
0.2
0.1
15.0
3.5
6.6
3.2
7.6
1.3
3.5
0.3
1.1
10.8
5.7
101.2
0.4
0.0
0.3
0.4
0.0
0.0
0.0
0.0
0.0
0.0
3.1
1.1
0.3
1.2
2.0
0.4
0.9
0.0
0.3
0.1
0.1
13.3
0.5
0.6
0.5
1.4
0.2
0.5
0.0
0.2
0.9
0.5
10.3
4
The data summarized in Table 1 were collected in a period of 12 months. Between 7 and
14 samplings were performed per month. To get a representative overview of the overall
exposure the passive diffusion monitors were allowed to be exposed at least 2 weeks.
The deviations of the concentrations of limonene indoor, i.e. high values in winter and
lower values in summer, fit well in the seasonal pattern of VOCs which was presented and
explained in deliverable D.2.2.2. The indoor/outdoor ratios of d-limonene shown in Table
2 reflect this seasonal cycle as well.
Table 2: Indoor/outdoor ratios of the concentrations of d-limonene in kindergartens
Jan Feb Mar Apr May Jun
Jul Aug Sep
Oct Nov Dec
no
no
no
140.9 152.6 147.8 63.9 57.8 value 53.8 54.2 value 142.2 317.5 value
This pattern was not found for alkanes and aromatics. Reasons could be seen in an
insufficient number of data per month, lower indoor temperatures and higher air exchange
rates in kindergartens than in common flats and apartments.
Therefore all indoor and outdoor data were accumulated and average values were
calculated, respectively. The indoor/outdoor ratios based on these average values are
given in Table 3.
Table 3: Indoor/outdoor ratios of 10 relevant VOCs and of the 29 VOC sum based on 97
indoor and 159 outdoor measurements in 34 kindergartens in Leipzig
VOC
indoor/outdoor ratio
Hexane
1.7
Decane
20.4
Benzene
1.2
Toluene
2.3
Ethylbenzene
4.1
m-, p-Xylene
4.0
Styrene
20.9
o-Xylene
4.2
55.1
-Pinene
d-Limonene
128.6
29 VOC Sum
7.2
2.1 Source dependence of relevant VOCs
It is obvious from Table 3 that there is no indoor/outdoor ratio smaller than 1 for human
relevant VOCs demonstrating that the collected data are plausible as long term
measurements. Values close to 1 indicate that these components are dominated from
outdoor sources. The only components with an indoor/outdoor ratio close to 1 are benzene
and to a lesser extent hexane. Benzene is usually associated with motor vehicle emission.
No significant indoor source seems to exist for benzene.
For hexane as an alkane an indoor/outdoor ratio of 1.7 was found. Therefore an influence
from outdoor sources can not be excluded as hexane is part of common petrol. Higher
alkanes like decane for example with an indoor/outdoor ratio of 20.4 originate from
indoor sources.
The aromatics with indoor/outdoor ratios between 2 and 4 can be emitted from both
outdoor sources (e.g. industrial facilities, power plants and mobile sources) and indoor
5
sources (e.g. tobacco smoke, paint and varnishes).
In contrast, components with indoor/outdoor ratios > 10 are predominantly coming from
indoor sources. Terpenes and terpenoids, especially the fragrance d-limonene are wellknown as emitted substances from cleaning products and room fresheners. It is worth to
mention the strong statistical spread in the measured concentrations of d-limonene in the
kindergartens (Table1, last column). These deviations in the data can only be explained by
a non static indoor source. The more or less frequent use of cleaning detergents and room
fresheners depends strongly on the attitude of the resident or in our case of the staff in the
kindergarten. The substance -pinene can be considered in the same manner and
additionally as an intrinsic component in wood and furniture.
3 Indoor/outdoor ratios of VOCs in different regions of Europe
3.1 Study design
A fundamental aim of the WP 2.2 in the NoMiracle project is to identify a complete
pattern of VOCs in indoor exposure scenarios regarding different life style and life
conditions across Europe. Secondly, differences in the temporal variability of VOCs
between regions with milder and rougher climate conditions should be found out.
Therefore two measuring campaigns in Leipzig were carried out under the frame of the
NoMiracle project. The results were associated with two measuring campaigns in different
seasons in Athens (Greece) and one in Arnhem (The Netherlands) carried out under the
frame of the AIRMEX project. The main focus of these campaigns was directed to public
buildings, kindergartens and schools. For receiving further information on the sources to
which humans are exposed in their daily life also homes of volunteers and the volunteers
themselves with a personal sampler were measured. The sampling was done with passive
diffusion monitors during a time period of one week for sampling inside and outside the
building (see Table 4) and of three days for personal sampling at a volunteer. 3M monitors
of the type OVM 3500 were used for the Leipzig campaign whereas Radiello VOC
samplers were applied for the campaigns in Athens and Arnhem. The comparability of the
achieved data for both types of sampling devices was demonstrated in deliverable D.2.2.2.
The first campaign in Athens was carried out in December 2003 (Athens I), the second in
October 2005 (Athens II), the first in Leipzig was done in April 2005 (Leipzig I) and the
second in July 2006 (Leipzig II):
Table 4: Placement of passive diffusion monitors
Buildings with public access
Kindergartens/Schools
Outside building
Outside building
Entrance hall
Classroom
Office
Home of volunteer
Home of volunteer
Volunteer
Teacher
Period of measurement
7d
7d
7d
7d
3d
3.2 Comparability of data sets
The data sets were created in terms of direct comparisons between the campaigns in
Athens, Arnhem and Leipzig. To simplify the analyzing procedure the list of quantified
VOCs was reduced to the 8 most relevant components for human health. Hexane from the
group of alkanes, benzene, toluene, ethylbenzene, m-, p-xylene, o-xylene from the
6
aromatics, -pinene and d-limonene from the terpenes were chosen.
To evaluate differences in the exposures in public buildings and kindergartens similar
numbers of locations for data collection were defined as shown in Table 5.
Table 5: Number of buildings chosen for data collection
Buildings with public access
Kindergartens
Schools
Athens I
2
2
1
Athens II
2
1
1
Arnhem
2
1
Leipzig I
3
3
Leipzig II
3
3
The main disadvantage for the comparison of the results is the limited number of data.
Due to a quite tight schedule for the measuring campaigns only 7-11 indoor measurements
and up to 7 outdoor measurements per campaign could be performed. These limitations
have to be considered in statistical interpretations of the data.
The determined concentrations of VOCs during the Leipzig campaign I and II fit well in
the confidence interval of the seasonal cycle of VOCs explained in deliverable D.2.2.2.
The indoor concentrations of VOCs obtained in Leipzig in July are only 55% of the
concentrations obtained in April. Regarding the model of a seasonal pattern of VOCs this
is plausible.
The deviations of the values gathered in Athens in October reach 75% of the values of
December. A model calculated for a seasonal cycle in Southern Europe doesn’t exist until
now. Thus, these variations have to be accepted without further interpretation.
3.3. Comparison of indoor/outdoor ratios of VOCs across Europe
Table 6 comprises the indoor/outdoor ratios of 8 human relevant VOCs sampled in cities
across Europe. The data base on average values for all indoor and outdoor measurements
in the cities Arnhem, Leipzig and Athens.
Table 6: Indoor/outdoor ratios of 8 VOCs based on average indoor and outdoor
concentrations of VOCs. nin, number of indoor measurements; nout, number of outdoor
measurements
VOC
Arnhem Leipzig I Leipzig II Athens I Athens II
Hexane
no value
2.0
1.2
1.6
1.4
Benzene
1.5
1.3
1.3
1.2
1.0
Toluene
1.1
4.3
4.0
1.7
1.1
Ethylbenzene
1.3
2.9
2.7
1.1
1.0
m-, p-Xylene
1.1
2.2
2.0
1.1
1.0
o-Xylene
1.4
2.5
2.5
1.0
0.9
17.9
24.0
39.6
5.3
6.8
-Pinene
Limonene
130.3
171.8
44.3
14.6
13.9
29 VOC Sum
4.0
3.0
3.1
1.6
1.5
nin
5
14
14
7
14
nout
3
7
7
5
4
It is obvious from Table 6 that the indoor/outdoor ratio of benzene is always close to 1 in
all cities measured without any correlation to certain seasons. This implies that burdens of
7
benzene are in any case dominated by outdoor sources.
A slight difference exists for the class of aromatics without benzene. Whereas the
indoor/outdoor ratio is close to 1 for xylene, ethylbenzene and toluene in Athens and
Arnhem the values in Leipzig are 2-fold and 4-fold, respectively. Special characteristics of
the data have to be taken into consideration: The data of Arnhem are based on 3 outdoor
and 5 indoor measurements which do not give a representative impression of the overall
burden especially inside buildings. As shown in Table 7 the outdoor sum concentrations
of aromatic compounds (benzene, toluene, ethylbenzene, m-, p-, o-xylene) in Athens are
approximately seven times up to twenty times higher than in Leipzig. The aromatic
compounds except benzene are emitted from both outdoor sources and indoor sources.
Due to high outdoor concentrations additional indoor sources can become less important
the measured value. The remarkably high outdoor concentration of aromatic compounds
in Athens can be ascribed to more traffic activity, different motor vehicles and more
industrial pollution than in Leipzig. As indoor sources for aromatic compounds tobacco
smoke, paints and varnishes should be considered.
Table 7: Indoor and outdoor concentrations of aromatics (benzene, toluene, ethylbenzene,
m-, p-, o-xylene) in µg/m3 in Athens and Leipzig based on 2 measuring campaigns
Athen I
Athens II Leipzig I Leipzig II
indoor
73.3
65.1
25.24
7.75
outdoor
51.8
61.9
8.38
3.0
The indoor/outdoor ratios of the terpenes exceed a value of 10 in most cases indicating an
indoor source. Differences in the indoor/outdoor ratios of the fragrance d-limonene in
Athens, Arnhem, and Leipzig are significant. Assuming d-limonene is coming from
cleaning detergents, fabric softeners and room fresheners the use of these products seems
to be more common in Middle Europe than in Southern Europe. On the other hand, due to
milder climate conditions in Southern Europe a much better air exchange is assured inside
the buildings and therefore accumulations of components with indoor sources are
diminished. The same considerations can be taken into account for -pinene.
4 Personal risk assessment of VOC uptake based on indoor/outdoor measurements
4.1 Theoretical and measured daily uptake of VOCs
To estimate the contribution of the indoor and outdoor microenvironments to the personal
exposure P we examined the time-weighted model
Pi  M ij t j  
where i is the index of the component and j the index of microenvironment M ( at work, at
home or outside), t is the fraction of time spent in microenvironment j, and  is an error
term for undefined times or factors, e.g. ventilation.
During the measuring campaigns in Leipzig the volunteers were asked how much time
they spend at home, at work and outside. Based on these statements a time-weighted daily
uptake of certain VOCs was calculated (see Figure 1). A breathing volume of 20 m3 per
day was assumed to calculate the uptake.
It is apparent from Fig.1 and consistent with the results reported in chapter 2.2 and 3.3
that the main uptake comes from the indoor microenvironment. For the aromatic
8
outdoor
at work
VOC Sum
d-Limonene
a-Pinene
o-Xylene
m, p -Xylene
Ethylbenzene
Toluene
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
Benzene
% of total burden
compounds as well as the VOC sum two third of the total burden can be ascribed to the
exposure at home. Times for travel, i.e. in cars or busses, times outside home for shopping
etc. are neglected in this example.
at home
Fig. 1: Dependence of the calculated personal uptake of VOCs on the microenvironments
work, home and outside. The data are based on time-weighted average values of indoor
and outdoor measurements in the campaign Leipzig I.
1600
VOC sum uptake [µg/d]
1400
1200
1000
800
600
400
200
re
pa
nc
na
di
sc
rs
o
pe
at
av. kindergartens
y
l
al
to
t
ho
m
e
k
wo
r
at
ou
td
o
or
0
av. public buildings
Fig. 2: The calculated VOC sum uptake outdoor, at work, at home, in total, the personal
uptake and the discrepancy of total and personal uptake. Data are based on average values
of the Leipzig I campaign (3 kindergartens, 4 public buildings).
9
To test the calculated time-weighted daily uptake the personal samplers of the volunteers
were analyzed and compared. Figure 2 shows the calculated daily uptake of VOC outdoor,
at work, at home and in total as well as the personal uptake analyzed from the personal
samplers. The discrepancy between the calculated total uptake and uptake from the
personal samplers are plotted in the last column. It is obvious that there is almost no
discrepancy for measurements in the public buildings and the volunteers therein in
contrast to the volunteers in the kindergartens. Reasons for the discrepancy in the
kindergartens can be seen in an inappropriate declaration of times spent at home or
elsewhere from the volunteers. Secondly, the personal samplers inside and outside were
allowed to be exposed at least seven days whereas the time period of the personal
samplers was settled to be as a rule only three days. The influence of the errors of
measurement can therefore be more significant for the personal samplers.
However, it can be concluded that if the fraction of time spent in a certain
microenvironment is determined properly the time-weighted model of exposure would
give a correct impression of the daily uptake of VOC.
4.1 Assessment of personal exposures to VOC across Europe
Assumed that the main burden of VOC in Europe originates from indoor sources (see
Tables 3 and 6) the personal risk should be dominated by indoor exposures. Therefore
personal/indoor ratios were calculated for 8 human relevant VOC. For that purpose
average values from all indoor measurements and personal measurement, respectively,
were calculated. The separated personal/indoor ratio per each volunteer was not possible
to calculate because of missing data of the volunteers in Arnhem and Athens.
Table 8: Personal/Indoor ratios of 8 VOC measured in the campaigns Arnhem, Leipzig I
and II and as average from the campaigns Athens I and II.
VOC
Athens
Arnhem
Leipzig I
Leipzig II
Hexane
1.2
no value
1.2
1.7
Benzene
0.9
1.4
1.5
1.8
Toluene
1.1
5.3
1.3
1.9
Ethylbenzene
1.0
2.2
1.2
1.2
m,-p-Xylene
1.6
3.7
1.4
1.5
o-Xylene
1.8
2.9
1.8
1.3
a-Pinene
3.8
1.1
0.9
0.4
d-Limonene
3.5
0.5
1.2
0.3
npersonal
11
5
7
7
Values close to 1 indicate that indoor concentrations dominate the personal exposure. This
is especially important for the aromatic compounds in Leipzig as the indoor
concentrations were two to four times higher. The personal/indoor ratios of the terpenes
are more complicated to interprete. Values > 1 imply that either the person was closer to
an emitting source than the passive diffusion monitor was, e.g. direct handling with
cleaning detergents or the person remained in rooms beyond those the passive diffusion
monitor was installed in. The latter can also be a reason for a personal/indoor ratio < 1.
10
The personal/indoor ratios of Arnhem can hardly be considered in the same manner
because of too less data.
5 Conclusion
The relative concentrations of VOCs measured indoor, outdoor and on persons (personal
exposure) are a function of relative indoor and outdoor source contributions and timeactivity patterns.
Many VOCs are emitted from both outdoor sources (e.g. industrial facilities, power plants,
mobile sources) and indoor sources (tobacco smoke, paints, varnishes, furniture and
household cleaners). The contribution of indoor sources, such as consumer products and
tobacco smoke is the largest source of variability in measured personal and indoor levels
of many compounds. Compounds associated with consumer products use include the
fragrances -pinene and d-limonene. The aromatic compounds have been shown to be
elevated in homes with smokers, but these compounds also originate from traffic and are
often higher in urban areas.
We have shown with the Leipzig and Arnhem campaigns (Middle Europe) that levels of
most VOCs are typically higher inside residences and buildings than in outdoor
microenvironments. Only benzene can be assigned to an outdoor source. The source
strength of indoor emissions has got a stronger influence than the infiltration of outdoor
air for many pollutants, especially those associated with fragrances. For the latter class of
substances the same is relevant for the campaigns in Athens as part of Southern Europe. In
contrast, the concentration of the aromatic compounds is almost the same indoors and
outdoors whereas the concentrations of aromatics in Athens are generally higher than in
Leipzig or Arnhem.
A time-weighted model of exposure using all measured microenvironments and timeactivity data can provide information about the daily uptake of VOC and can be used for
personal risk assessments.
11