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. 2.2.2 Report on Temporal and spatial variability of human exposure –
related VOC
Due date of deliverable: October 31, 2005 Actual submission date: October 31, 2005
Start date of project: 1 November 2005
Duration: 5 years
Organisation name of lead contractor for this deliverable: NERI
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:
Martina Rehwagen, Uwe Schlink and Tibor Kohajda, UFZ, Partner 3
Diana Rembges, Otmar Geiss, Salvatore Tirendi, Dimitrios Kotzias, JRC,
Partner 18
Deliverable no:
D.2.2.2
Status: Draft
Nature:
Report
Dissemination
level: PU
Date of delivery:
October 31, 2005
Date of publishing:
Reviewed by (period and name):
Deliverable reference number and title:
D.2.2.2 Report on Temporal and spatial variability of human exposure –
related VOC
Due date of deliverable: October 31
Actual submission date: October 31, 2005
Report on temporal and spatial variability of human exposure-related VOC
Martina Rehwagen1, Uwe Schlink1, Tibor Kohajda1, Otmar Geiss2, Salvatore Tirendi2, Dimitrios
Kotzias2, Diana Rembges2 and Olf Herbarth1,
1
UFZ Centre for Environmental Research
Join Research Centre
2
List of contents
1
Introducing remarks
2
Results from pilot studies
2.1
Temporal variability of human-exposure related VOC at different localities
(UFZ)
Application of seasonal adjustment (UFZ)
Relevant results of the “Indoor Air Monitoring and Exposure Assessment Study
(AIRMEX)” of the JRC Ispra
2.2
2.3
3
Extended Investigations of the temporal and local variability of indoor VOC
patterns
3.1
3.2
3.3
3.4
3.5
Study design
Description of the investigated buildings (rooms) and applied measurement
techniques
Comparison of the used measurement methods
Seasonal pattern of the VOC spectrum
Spatial variability of human exposure related VOC in different types of rooms
4
Conclusions
1
Introducing remarks
On the basis of 2103 passive measurements of volatile organic compounds (VOCs) in indoor
air sampled with 3M monitors of the type OVM 3500 we studied the intensity of a seasonal
pattern. The data are representative for the German population and were gathered in different
cities, in rooms of different type (children's, living, sleeping rooms, and other rooms), and in
households of smokers and non-smokers. The analysis comprised concentrations of 30 VOCs
belonging to the groups of alkanes, cycloalkanes, aromatics, volatile halogenated
hydrocarbons, and terpenes. For statistical processing, GenStat 6.1 was applied.
As the data did not follow a normal distribution function, we used the Mann-Whitney U-test
and the H-test of Kruskal-Wallis to detect significant differences between monthly groups of
data. These tests refer only to the statistics of the data and do not include the measurement
errors.
The knowledge about the seasonal pattern is a precondition to compare the exposure situation
of different localities using a standardization procedure.
2
Results from pilot studies
A total of 2103 VOC samples were taken in different apartments and different urban German
areas. Some statistics of the measurements are presented in Table 1.
Table 1: Summary statistics of 30VOC concentrations (in µg/m³) observed in 2103
dwellings in different German cities
30-VOC sum
2.1
Mean
188.2
Median
129.4
95-perc
505.9
98-perc
748.6
Stddev
235.1
Max
4597.1
Temporal variability of human-exposure related VOC at different localities
Applying the Kruskal–Wallis test, for each site we found statistically significant differences
(p<0.01) between monthly median concentrations. To study if this monthly variation is
irregular or if it follows an annual cycle we considered monthly box-plots of the 30-VOC
sum. Our results provide strong evidence of a clear seasonal variation. Median values of VOC
concentrations are higher in winter and lower during summer months as can be seen for the
30-VOC concentration in Fig. 1.
To assess the statistical significance of the seasonal pattern, to estimate the amplitude of the
annual cycle of indoor VOCs, and to enable a conversion between concentrations observed in
different months, we fitted a seasonal model to the logarithms of the concentration values.
The predictors are harmonic functions of the time (m in months) and the coefficients have
been estimated by means of regression analysis. For the 30-VOC concentration we found this
model to be statistically significant (p<0.01), indicating a seasonal pattern.
The model identified for the 30-VOC sum concentration measured is (R²=0.97):
log(medVOC(m))=4.88 + 0.35 cos(2πm/12) + 0.20 sin(2πm/12)
(1)
Based on equation (1) we calculated factors that relate for every month the median to the
annual maximum that mostly occurs in January (Table 2).
Fig. 1: Seasonal variation of 30-VOC concentration of 2103 indoor measurements,
(median with 95% confidence interval).
As these factors are determined by indoor sources and ventilation behaviour, they may depend
on the room where the sampling was made. Studying this effect, we calculated the adjustment
factors separately for VOC concentrations sampled in the children’s rooms. We found out that
the adjustment factors are determined by both the urban area and the type of the room.
Table 2: Factors for seasonal adjustment of indoor 30VOC concentrations at different
apartments and, additionally, for bedrooms of children.
Month
Jan Feb
all apartments
30 VOCs
1.0 1.1
children’s
30 VOCs
1.0 1.0
Mar Apr Mai Jun
Jul
Aug Sep
Oct Nov Dec
1.2
1.5
1.8
2.1
2.2 2.1
1.8
1.5
1.2
1.1
1.2
1.4
1.8
2.2
2.5 2.5
2.2
1.7
1.4
1.1
2.2
Application of seasonal adjustment
From our measurements we conclude that in an assessment of indoor air quality the season
when sampling occurs must be taken into consideration. One possibility for doing this might
be the introduction of seasonally dependent reference values. Another way is to adjust the
observations. For that purpose, a harmonic function was fitted to the logarithms of the VOC
concentrations. For each observation in any specific month m the corresponding annual
maximum value, mostly occurring in January, can be calculated using model (1). Another
way for seasonal adjustment is to use a factor (see Tables 3), which was calculated from the
fitted model and depends on the month.
We illustrate the adjustment procedure by help of the following example: if a 30-VOC sum
concentration of 150 µg/m3 is registered in June, one can assume that the maximum value will
occur in January and will amount to 150 * 2.1 = 315 µg/m3. This means that the reference
value of 300 µg/m3 will most likely be exceeded, although the value measured in June lay
beneath this level.
The seasonal pattern strongly depends on (a) the indoor sources, which in turn are determined
by the furnishing and the number of occupants and their activities, (b) the ventilation rate,
depending on the fabric of the building and the ventilation behaviour, and (c) the impact of
outdoor environmental conditions, such as elevated air-pollution in the proximity of busy
roads or city centers that, in turn, may vary seasonally.
2.4
Relevant results for WP 2 from the “Indoor Air Monitoring and Exposure
Assessment Study (AIRMEX)”
As a first approach to systematically evaluate the relationship between indoor air pollution
and human (chronic) exposure to pollutants the JRC institute for Health and Consumer
Protection (IHCP) in Ispra has launched in 2003 the AIRMEX project. The aim of this
ongoing project is 1. to identify and quantify the main pollutants in indoor environments and
in particular in public buildings, kindergardens and schools, 2. to identify the sources of these
pollutants, 3. to estimate the people’s exposure to these pollutants while working/remaining in
the monitored areas and 4. to investigate relationship between ambient background
concentrations and personal exposure.
In the frame of this project measurement campaigns are carried out in pre-selected indoor
environments in various cities in Southern and Central Europe (Catania, Athens, Arnhem,
Nijmegen, Brussels, Thessaloniki) during which the indoor/outdoor relationships and personal
exposure concentrations for selected volatile organic compounds are estimated.
50
Benzene
45
Toluene
42,9
Ethylbenzene
40
Concentration [ug/m3]
m/p-Xylene
35
o-Xylene
31,2
30
28,7
26,8
25
22,3
20,9
20
18,5
15
9,8
10
14,1
13,4
13,3
10,9
7,1
5
4,7
4,9
5,4
5,9
4,5
4,7
5,5
4,4
4,8
5,2
4,6
4,9
0
Vol 1
Vol2
Office
Hall
Outside
Fig.2: Comparison of BTEX in the "Sede Distretto Sanitario Catania 2" AIRMEX Catania
Figure 2 gives a typical example of the BTEX concentrations achieved in a Southern
European City. The lowest BTEX air concentrations are determined outside, while already
inside the building, in this case a public building, the concentrations are higher. But looking
for the personal exposure the BTEX concentration measured with the help of volunteers are
significantly higher than either both indoor and outdoor concentrations.
For receiving further information on the sources to which humans are exposed in their daily
life also other environments like households or inside cars have been measured. In the course
of a recent measurement campaign organized at Thessaloniki in June 2005 high
concentrations of toluene and m/p xylene up to 200 respectively 235 μg/m3 inside cars have
been measured while in the office the values were 74 respectively 53 μg/m3 for toluene and
m/p xylene. Compared to outdoor measurements at streets in front of public buildings these
values ranged from 17 to 36 μg/m3 for toluene and 10 to 19 μg/m3 for m/p xylene. These data
highlight clearly the major impact of pollutants occurring indoors to human exposure.
Preliminary results achieved during these measurement campaigns in the frame of AIRMEX
in various European cities indicate clearly, that indoor air concentrations for volatile organic
compounds (VOCs) as well as for aldehydes are generally higher or similar to those of
outdoor air. Compared to indoor and outdoor concentrations the personal exposure
concentrations are generally even higher.
3
Extended Investigations of the temporal and local variability of indoor VOC
patterns
3.1
Study design
While a general set of factors for seasonal adjustment is not recommendable further research
will be necessary to disentangle the multi-factorial effects of indoor environment and sources,
outdoor meteorological conditions and air pollution and ventilation habits on indoor VOC
concentrations. Continuing the investigation of the factors of influence seasonal indoor VOC
patterns in Europe in the scope of the NoMiracle project were more cities and room types
included. The aim is to look for differences in the temporal variation between cities in warmer
and colder regions of Europe and in different types of rooms. Therefore the first measurement
campaigns in cooperation with the Joint Research Centre were started.
Beside the target to investigate the differences between indoor, outdoor and personal VOC
exposure another target is the expansion of the examination of seasonal indoor VOC patterns
to other European urban areas, which was already started by the JRC in the scope of the
AIRMEX project. In the AIRMEX project the main focus was on the VOC exposure in public
buildings, kindergartens and schools, while the UFZ mainly investigated the human VOC
exposure in living and children’s rooms.
The first measurement campaign where JRC and UFZ cooperated was carried out in Leipzig
in April 2005. It was used to ensure the comparability of the data received by different types
of passive samplers from both institutes as prerequisite to create a common data pool. In
seven buildings in Leipzig (4 public buildings and 3 kindergartens) passive sampling devices
have been placed in the following locations.
•
measurements per building
outdoor
office/classroom
home
volunteer/teacher (personal)
•
types of used passive sampler:
Radiello VOC CS2
Radiello VOC Thermodesorption
3M (OVM 3500)
stainless steel tubes with Tenax
Radiello aldehyde
3.2
Description of the investigated buildings (rooms) and applied measurement
techniques
Table 3: Placement of Samplers
Buildings with public access
VOC
Radiello
(CS2Elution)
Outside Building
JRC
Entrance Hall
JRC
Office
JRC, UFZ
Home of
Volunteer
Volunteer
JRC, UFZ
VOC 3M
(CS2Elution)
UFZ
VOC
Tenax
VOC
Radiello
ThermoThermodesorption desorption
UFZ
Time of Aldehyd Time of
measurem
es
measurem
ent
Radiello
ent
[days]
[days]
UFZ
UFZ
7
7
7
UFZ
UFZ
7
UFZ
UFZ
JRC(3d)
VOC 3M
VOC
Tenax
VOC
Radiello
7
JRC
JRC
JRC,
UFZ
JRC,UF
Z
JRC
7
7
7
7
3
Kindergartens
VOC
Radiello
(CS2Elution)
Outside Building
JRC
Classroom
JRC, UFZ
Home of
Volunteer
Teacher
3.3
JRC, UFZ
(CS2Elution)
UFZ
UFZ
ThermoThermodesorption desorption
UFZ
UFZ
UFZ
UFZ
UFZ
UFZ
Time of Aldehyd Time of
measurem
es
measurem
ent
Radiello
ent
[days]
[days]
7
7
7
JRC(3d)
7
JRC
JRC,
UFZ
JRC,
UFZ
JRC
7
7
7
3
Comparison of the used measurement methods
Medium VOC concentrations received with different samplers from 14 parallel measurements
are shown in figure 3.
With the Mann-Whitney-U-Test it was determined if there a significant difference exists in
the results gained with different passive samplers.
conc. [µg/m³]
30
25
Rad. UFZ CS2 (n=14)
Rad. Ispra CS2 (n=14)
20
3M UFZ (n=14)
Tenax UFZ (n=14)
15
10
5
0
e
z en
ben
ne
ene
ene
xy le
tol u
e nz
b
l
p
y
m+
eth
e
ren
s ty
y
o-x
e
e
ne
nen
z en
in e
i mo
ben
a-p
l
l
y
eth
-trim
4
,
1,2
e
len
Fig. 3: VOC concentrations with different passive samplers
The results show that the results received by both institutes with Radiello DNPH samplers fit
best and that in the results gained with Radiello VOC CS2 samplers from JRC (RIspCS2) and
3M samplers from the UFZ there were only 2 significant differences form 9 measured
components. That is the proof that results gained in former measurements by both institutes
are comparable and can be used for further investigations as well as in pooled studies.
However the data achieved during the measurement campaign show comparable values to the
results achieved during measurement campaigns in frame of the AIRMEX project at
comparable sites. BTEX concentrations in public building of Nijmegen and Arnhem ranged
e.g. for toluene between 3 and 11 μg/m3.
Because of organizational reasons there will be only two measurement campaigns for further
investigation of the seasonal pattern in further European cities per city and year. In these
further campaigns the measured VOC spectrum will be reduced to 8 main components
(Table 4). The results received with these 8 components in different cities in the scope of the
AIRMEX project will be included in the analysis.
Table 4: 8 VOC list
3.4
benzene
styrene
toluene
o - xylene
ethylbenzene
 -pinene
m+p - xylene
limonene
Seasonal pattern of the VOC spectrum
When examining if the seasonal pattern of the reduced VOC spectrum can fulfil the described
function of the 30 VOC, too, a positive match has been found (Fig. ).
The model identified for the 8 VOC sum concentration measured at all apartments is
log(med(8VOC(m))=4.32 + 0.41 cos(2πm/12) + 0.16 sin(2πm/12)
(2)
with R²=0.97
Fig. 4: Seasonal variation of 8 VOC sum concentration of 2103 indoor measurements
(median with 95% confidence interval).
The calculated adjusting factors of the 8 VOCsum to normalize the seasonal changes in the
indoor air measurements are comparable with those of the 30 VOC sum, too (Table 5).
Table 5: Factors for seasonal adjustment of indoor 30 VOC and 8 VOC
concentrations
Month
30VOC
8VOC
Jan
1.0
1.0
Feb
1.1
1.1
Mar Apr Mai Jun
1.2 1.5 1.8 2.1
1.3 1.7 2.0 2.4
Jul Aug Sep
2.2 2.1 1.8
2.4 2.2 1.8
Oct Nov Dec
1.5 1.2 1.1
1.5 1.2 1.0
3.5 Spatial variability of human exposure related VOC in different types of rooms
Previous studies (paragraph 2) showed that you can find seasonal fluctuations both in
children's rooms and in other room categories/types. It is still impossible to make a conclusion
about the absolute exposure in the individual room types and the personal exposure.
Comparing the data of the VOC exposure in the different kinds of rooms and the personal
VOC exposure collected in the joint measuring campaign of JRC and UFZ in April in Leipzig
it could be stated that significantly different exposure at different places exists. The personal
exposure is reflected best by the exposure at home as expected according to the duration of
stay (Fig. 4).
120
100
VOC Sum
80
60
40
20
m ean
m ean±0,95 CI
0
hom e
work
personal
Fig. 5 mean VOC concentration at different places
With the further differentiation of room types it could be stated that the VOC concentrations
in the kindergartens are lower than those in the offices and homes (Fig. 5). With the analysis
of data of parallel running studies further differentiations between children's rooms and living
rooms we possible, whereby children's rooms seemed to be more highly exposed than the
living rooms.
It won’t be possible in every case to measure the personal exposure directly at the person. It is
acceptable to assess the VOC exposure in the dwelling to determine the available personal
exposure.
120
100
VOC Sum [µg/m³]
80
60
40
20
0
mean
mean±0,95 CI
-20
kindergarten
office
living rooom
Fig. 6 different types of rooms
4
Conclusions
The result of our pilot study can be summarised as follows:
(i)
a seasonal pattern was observed in VOC data gathered in Germany; a model and
adjustment factors are provided.
(ii)
8 VOC components have been selected, which ensure comparability of UFZ and
JRC measurements.
(iii)
the seasonality is obvious also for the selected 8 VOC components; a model and
adjustment factors are provided.
(iv)
different room types have different VOC exposure, on the average children's
rooms and living rooms are more burdened than office rooms, kindergartens show
the lowest VOC concentrations.
On the basis of our previous and extended investigations we conclude that
(a) the AIRMEX data can be combined with UFZ data in order to create a database that
represents different European regions.
(b) this database shall be used in the future NoMiracle project work to analyse the annual
pattern in regions having different climatic conditions.
An interesting question is if the amplitude of the seasonality depends on the latitude of the
sampled region. In addition it is of interest whether the VOC load in different types of rooms
can be distinguished also in other countries or societies similarly.