Volatile organic compounds (VOCs) play an important role in indoor and outdoor air pollutants. In the present study, samples were analyzed from indoor (schools and houses) and outdoor air in urban, industrial, semi-rural and residential areas from Argentina (La Plata region) and Mexico (Mexico City region) to consider VOC exposure in different types of environments. VOCs were sampled using a passive sampling method with passive 3M monitors. Samples were extracted with CS2 and analyzed by GC/MS detectors.
The results show significant differences in concentration and distribution between indoor and outdoor samples, depending on the study area. Most VOCs predominantly originated indoors influenced by local outdoor emissions (traffic and industry).Facultad de Ciencias Exacta

Herbarth, O.

Massolo, Laura Andrea

Mller, A.

Tovalin, H.

SEDICI - Repositorio de la UNLP

Air Pollution XVI 467
Comparative study of indoor-outdoor exposure 
against volatile organic compounds in
South and Middle America
O. Herbarth1, A. Müller2, L. Massolo3 & H. Tovalin4
1 Department Environmental Medicine and Hygiene, Faculty of Medicine, 
University of Leipzig, D-04103 Leipzig, Germany 
2UFZ-Centre for Environmental Research,
Department of Human Exposure Research and Epidemiology, 
D-04318 Leipzig, Germany
3Centro de Investigaciones del Medio Ambiente,
Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 
Argentina
4División de Estudios de Posgrado e Investigación, FES-Zaragoza, 
Universidad Nacional Autónoma de México (UNAM), México D.F., 
Mexico
Abstract
Volatile organic compounds (VOCs) play an important role in indoor and 
outdoor air pollutants. In the present study, samples were analyzed from indoor 
(schools and houses) and outdoor air in urban, industrial, semi-rural and 
residential areas from Argentina (La Plata region) and Mexico (Mexico City 
region) to consider VOC exposure in different types of environments. VOCs 
were sampled using a passive sampling method with passive 3M monitors. 
Samples were extracted with CS2 and analyzed by GC/MS detectors.
The results show significant differences in concentration and distribution 
between indoor and outdoor samples, depending on the study area. Most VOCs 
predominantly originated indoors influenced by local outdoor emissions (traffic 
and industry).
Keywords: VOCs, indoor-outdoor ratio, urban and industrial burdens, indoor 
sources.
WIT Transactions on Ecology and the Environment, Vol 116, © 2008 WIT Press
www.witpress.com, ISSN 1743-3541 (on-line)
doi:10.2495/AIR080471
468 Air Pollution XVI
1 Introduction
Volatile organic compounds (VOCs), arising from natural and anthropogenic 
processes represent an important group of indoor and outdoor air pollutants, 
because they are ubiquitous and associated with increased long-term health risks 
[1, 2], for the general population and those people that stay outdoors for a long 
time [3], Vehicular and industrial emissions are the major sources of outdoor 
VOCs. It has been estimated that 35% of total VOC emissions are due to vehicle 
exhaust and evaporative losses [4-6],
Indoor VOC exposure is thought to be of greater concern in the community 
because indoor concentrations of many pollutants are often higher than those 
typically encountered outdoors. At the same time, indoor VOC concentration 
may be the dominant contributor to personal exposure because most people 
spend over 80% of their time indoors, either in the home or in the work place 
[7, 8], Measurement of VOCs in the indoor environment has received substantial 
research attention for several years because indoor VOC levels may pose 
potential health effects to occupants of dwellings. While some VOCs may be 
present at concentrations that are not considered acutely harmful to human health 
with short-term exposure, long-term exposure may result in mutagenic and 
carcinogenic effects.
The occurrence and concentrations of VOCs in residences can be affected by 
outdoor atmospheric conditions, indoor sources, indoor volume, human 
activities, chemical reactions, ventilation rates, and seasonal factors [9, 10],
Indoor sources are quite numerous including combustion products, cooking, 
construction materials, furnishings, paints, varnishes and solvents, adhesives and 
caulks, office equipment and consumer products [11-13],
To consider the VOC exposure in the different types of environments, 
measurements of VOC concentrations were carried out indoors and outdoors in 
areas influenced by industrial emissions, in an urban area influenced by traffic, 
as well as in semi-rural and residential areas as control and as an area influenced 
by emissions coming from the (mega)-city. The indoor-outdoor ratios were 
calculated to get an impression regarding the sources of VOC exposure and the 
impact of outdoor-related air pollution on the indoor environment.
2 Methods
2.1 Measurement sites
The study region, La Plata and neighboring areas, located northeast of Buenos 
Aires province (Argentina), has a population around 700,000 inhabitants. Four 
sampling zones were considered: industrial (I), urban (U), semi-rural (SR) and 
residential (R) areas (Figure 1).
The industrial area holds the country’s main oil refinery (total crude oil 
distillation capacity: 38,000 m3/day_1) located next to six petrochemical plants 
producing diverse compounds such as aromatics (benzene, toluene, xylenes), 
aliphatic solvents (n-pentane, n-hexane, n-heptane), polypropylene, polybutene, 
WIT Transactions on Ecology and the Environment, Vol 116, © 2008 WIT Press
www.witpress.com, ISSN 1743-3541 (on-line)
Air Pollution XVI 469
maleic anhydride, cyclohexane, methanol, methyl tertiary butyl ether, and 
petroleum coke. This industrial complex is approximately 10 km north-northeast 
of the main urban sector of the city.
The urban area is characterized by heavy traffic; the number of vehicles 
registered is approximately 200,000. The semi-rural and residential sites, places 
with low traffic, were considered control areas.
Figure 1 : Sampling points in La Plata (I, industrial; U, urban; SR, semi- 
rural; R, residential).
Figure 2: Sampling points in Mexico (TOurban, T1 suburban, T2 rural).
WTT Transactions on Ecology and the Environment, Vol 116, © 2008 WIT Press
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470 Air Pollution XVI
The Mexico study is part of the MIL AGRO project (Megacity Initiative: 
Local and Global Research Observations) [16], The air pollution problem in 
megacities is influenced by several factors that include the topography, 
meteorology, demographic growth, industrial growth and urban expansion.
The Mexico City Metropolitan Area (MCMA) - the second largest megacity 
in the world - has an estimated population of 18 million people and covers an 
urbanized area that totals 1,500 km2, encompassing the 16 delegations of the 
Federal District, 37 municipalities of the State of Mexico and 1 municipality of 
the State of Hidalgo. In the MCMA, emissions of pollutants reach millions of 
tons per year, and atmospheric concentrations of ozone and particulate matter 
routinely exceed the standards recommended by the World Health Organization
[6],  As a result, there has been an increase in diagnosed incidences of chronic 
bronchitis, asthma, reduction of pulmonary capacity, and in premature mortality 
rates among the citizens. The study region, Mexico City and the neighboring 
areas in main wind direction (SW to NE) includes three different sites (TO, Tl, 
T2): TO - within MCMA located at Iztapalapa, Tl - at the Universidad 
Tecnologica de Tecamac in the State of Mexico, T2 in Rancho La Bisnaga, north 
of Tizayuca in the State of Hidalgo (Figure 2). The designations refer to transport 
of the urban plume to different points in space and time. The selected VOC 
represent alkanes, cycloalkanes and aromatics, chloroaromatics, terpenes.
2.2 Sampling design and measurement method
Sampling was carried out in indoor and outdoor air using passive sampler (3M 
OVM 3500, 1986) [14], A sampling period of four weeks was selected, since an 
integrative sampling described a mean load relative to personal exposure. Using 
this procedure, it can be assumed that the human exposure is more selectively 
described compared with a short time measurement. Indoor samples were 
collected in kindergartens, schools, offices and in the selected homes of children, 
while outdoor samples were collected in representative sites parallel to the 
indoor measurement. The outdoor monitors were placed at rain-protected 
positions. Indoors, the passive monitors were placed in the middle of the room at 
a 1.5-2 m height with a minimum distance of 50 cm to the ceiling [7, 15],
According to their structure and composition the VOC belong to the 
following groups: alkanes (hexane, heptane, octane, nonane, decane, undecane, 
dodecane, tridecane); cycloalkanes (methylcyclopentane, cyclohexane, 
methylcyclohexane); aromatic hydrocarbons (benzene, toluene, ethylbenzene, 
m+p-xylene, styrene, o-xylene, 4-ethyltoluene, 3-ethyltoluene, 2-ethyltoluene, 
naphthalene); chlorinated hydrocarbons (chlorbenzene, trichlorethylene, 
tetrachlorethylene); terpenes (a-pinene, b-pinene, 2-carene, 3-carene, limonene).
After exposure, the VOCs were desorbed from the adsorption layers (charcoal 
pads) by means of 1.5 ml of carbon disulfide (with low benzene, from Merck) 
containing 1% of methanol. The VOC analysis was performed on a PerkinElmer 
gas chromatograph with a masspectrometrical detector, equipped with an RTX-1 
column (60 m 0.32 mm I.D., 1.0 pm film thickness; Restek). The oven 
temperature was held at 43 °C for 5 min, and then programmed to 200 °C at a 
rate of 2.5 °C min1. The injector temperature was held at 250 °C as well as the 
WIT Transactions on Ecology and the Environment, Vol 116, © 2008 WIT Press
www.witpress.com, ISSN 1743-3541 (on-line)
Air Pollution XVI 471
transfer line temperature. An electron energy of 70 eV was used for ionization. 
The source temperature was held at 200 °C. A sample volume of 1 pl was 
splitless injected. Integrated areas of selected fragment ions from each of the 29 
VOCs were obtained with the software Turbomass, Version 4.4 (PerkinElmer) 
[7, 10],
2.3 Quantification and statistical analysis
Recovery coefficients were determined by direct injection of a known amount of 
the standard into a 3M sampler and subsequent extraction with carbon disulfide 
containing 1% methanol. The recovery was between 98% and 102%. For the 
studied VOCs, the background amounts contained in the monitors and in the 
carbon disulfide were determined for each charge of the samplers and chemicals 
and were subtracted from the sample results. The detection limits for the 
components were estimated as the three-fold standard deviation of five replicate 
measurements of monitor blanks. For components with blank values too low to 
be registered, it is usual practice to use the three-fold standard deviation of 
replicate measurements of a low-level standard solution [15], The average 
concentration of each component over the sampling interval (in pg m-3) was 
calculated according to the equation adopted from 3M [14], using the adsorption 
coefficients in charcoal. The detection limits were found to be between 0.01 and 
0.05 mg m-3 regarding a sampling interval of 4 weeks.
A non-parametric method (Mann-Whitney U-Test) was used for statistical 
analysis of results, according to the non-symmetrical distribution of the data. 
Statistical analysis and plots of median values were prepared using Statistica 7.1
[17] , A p-valuc below 0.05 was regarded to be statistically significant.
3 Results and discussion
3.1 Total VOCs load
The concentration levels of the total indoor and outdoor VOC content per study 
area is shown in Figure 3a and 3b.
Significantly higher concentrations of indoor VOCs were observed 
independent from the study and local area.
3.2 Indoor-outdoor ratio
Since most people spend over 80 percent of their time indoors [10], indoor VOCs 
are thought to be of greater concern considering potential health effects because 
the indoor concentrations of these compounds are often higher than those 
typically encountered outdoors. On the one hand the indoor-outdoor ratio (I/O) is 
generally used to infer penetration to indoor environments and indoor sources
[18] , On the other hand this ratio will be determined also by the use of the 
buildings. It makes a difference whether the building is mainly used for 
apartments or for public demands. An I/O ratio lower and close to one indicates 
WIT Transactions on Ecology and the Environment, Vol 116, © 2008 WIT Press
www.witpress.com, ISSN 1743-3541 (on-line)
472 Air Pollution XVI
more outdoor sources. Significant differences between indoor and outdoor 
concentrations indicate mainly indoor sources for the VOC compounds.
The I/O ratio of the apartments in the urban and suburban areas is similar 
(between 2.5 and 2.7).
The ratio is lower for the schools/offices than for the apartments. This reflects 
the lower indoor exposure in the public building coming from a reduced use of 
indoor exposure causing materials and maybe from a reduced redecoration 
activity but a better air exchange rate.
□ indoor
□ outdoor
(a)
□ indoor
□ outdoor
(b)
Figure 3: (a) Indoor and outdoor concentration of VOC (sum of measured
VOC) in La Plata and surroundings (mean values), (b) Indoor and 
outdoor concentration of VOC (sum of measured VOC) in 
different building types in Mexico City and surroundings (mean 
values).
WIT Transactions on Ecology and the Environment, Vol 116, © 2008 WIT Press
www.witpress.com, ISSN 1743-3541 (on-line)
Air Pollution XVI 473
The main sources are the industrial complex and the traffic. The highest 
outdoor exposure was measured in the industrial area of La Plata following by 
the traffic dominated exposure in the urban area of Mexico City. The lowest load 
was recorded in the mral respectively semi-rural sites of both study areas.
4 Conclusions
Ambient air in the vicinity of the industrial and urban site is significantly 
different than the air quality found in the semi-rural and suburban residential 
areas. Whereas traffic was identified as the main source of outdoor VOC 
exposure in the urban and residential areas, in the industrial area, outdoor as well 
indoor air is strongly affected by emissions of the local industry.
Total VOCs in the urban, residential and semi-rural areas are equivalent to 
those reported for other major cities worldwide, indicating comparable burdens, 
although non-equivalent distribution patterns could be a result of different 
lifestyles and habits.
Indoor/outdoor ratios suggest higher indoor burdens in all places and 
demonstrate an exceptional importance of indoor exposure.
The high outdoor VOC content in the industrial and “high” traffic loaded 
area, together with the lifestyle quality, very strongly affected the indoor 
exposure for these inhabitants.
Further research will be necessary to evaluate the environmental impact of 
VOCs and the assessment of effects of the different volatile compounds on 
human health.
Acknowledgements
Parts of this study were supported by the International Bureau of the German 
Federal Ministry of Education and Research, the Secretary of Science and 
Technology and Province Research Council of the Province of Buenos Aires 
(CICPBA), the National Research Council of Argentina (CONICET), the 
Metropolitan Environmental Commission of México City and the Molina Center 
for Energy and the Environment. The authors would also like to thank Brigitte 
Winkler for her excellent assistance in the chemical analyses, and Jephte Cruz 
for her assistance during the monitoring.
References
[1] WHO (World Health Organization). Protection of the Human Environment. 
The health effects of indoor air pollution exposure in developing countries, 
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[2] Brown, S.K. Volatile organic compounds in new and established buildings 
in Melbourne, Australia. Indoor Air. 12:55-63, 2002.
[3] Tovalin, H., Whitehead, L. Personal exposure to volatile organic 
compounds among outdoor and indoor workers in two Mexican cities. 
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[4] Herbarth, O., Rehwagen, M., Ronco, A. The Influence of Localized 
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O. Seasonal cycle of indoor-VOCs: comparison of apartments and cities. 
Atmos Environ. 38: 1181-1190, 2004.
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[15] Begerow J, Jermann E, Kelles T, Ranft U, Dunemann L. Passive sampling 
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[16] MILAGRO-Factsheet 2006: http://www.eol.ucar.edu/projects/milagro/ 
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English

Comparative study of indoor-outdoor exposure against volatile organic compounds in South and Middle America

Servicio de Difusión de la Creación Intelectual

Air Pollution XVI 467Comparative study of indoor-outdoor exposure against volatile organic compounds inSouth and Middle AmericaO. Herbarth1, A. Müller2, L. Massolo3 & H. Tovalin41 Department Environmental Medicine and Hygiene, Faculty of Medicine, University of Leipzig, D-04103 Leipzig, Germany 2UFZ-Centre for Environmental Research,Department of Human Exposure Research and Epidemiology, D-04318 Leipzig, Germany3Centro de Investigaciones del Medio Ambiente,Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina4División de Estudios de Posgrado e Investigación, FES-Zaragoza, Universidad Nacional Autónoma de México (UNAM), México D.F., MexicoAbstractVolatile organic compounds (VOCs) play an important role in indoor and outdoor air pollutants. In the present study, samples were analyzed from indoor (schools and houses) and outdoor air in urban, industrial, semi-rural and residential areas from Argentina (La Plata region) and Mexico (Mexico City region) to consider VOC exposure in different types of environments. VOCs were sampled using a passive sampling method with passive 3M monitors. Samples were extracted with CS2 and analyzed by GC/MS detectors.The results show significant differences in concentration and distribution between indoor and outdoor samples, depending on the study area. Most VOCs predominantly originated indoors influenced by local outdoor emissions (traffic and industry).Keywords: VOCs, indoor-outdoor ratio, urban and industrial burdens, indoor sources.WIT Transactions on Ecology and the Environment, Vol 116, © 2008 WIT Presswww.witpress.com, ISSN 1743-3541 (on-line)doi:10.2495/AIR080471468 Air Pollution XVI1 IntroductionVolatile organic compounds (VOCs), arising from natural and anthropogenic processes represent an important group of indoor and outdoor air pollutants, because they are ubiquitous and associated with increased long-term health risks [1, 2], for the general population and those people that stay outdoors for a long time [3], Vehicular and industrial emissions are the major sources of outdoor VOCs. It has been estimated that 35% of total VOC emissions are due to vehicle exhaust and evaporative losses [4-6],Indoor VOC exposure is thought to be of greater concern in the community because indoor concentrations of many pollutants are often higher than those typically encountered outdoors. At the same time, indoor VOC concentration may be the dominant contributor to personal exposure because most people spend over 80% of their time indoors, either in the home or in the work place [7, 8], Measurement of VOCs in the indoor environment has received substantial research attention for several years because indoor VOC levels may pose potential health effects to occupants of dwellings. While some VOCs may be present at concentrations that are not considered acutely harmful to human health with short-term exposure, long-term exposure may result in mutagenic and carcinogenic effects.The occurrence and concentrations of VOCs in residences can be affected by outdoor atmospheric conditions, indoor sources, indoor volume, human activities, chemical reactions, ventilation rates, and seasonal factors [9, 10],Indoor sources are quite numerous including combustion products, cooking, construction materials, furnishings, paints, varnishes and solvents, adhesives and caulks, office equipment and consumer products [11-13],To consider the VOC exposure in the different types of environments, measurements of VOC concentrations were carried out indoors and outdoors in areas influenced by industrial emissions, in an urban area influenced by traffic, as well as in semi-rural and residential areas as control and as an area influenced by emissions coming from the (mega)-city. The indoor-outdoor ratios were calculated to get an impression regarding the sources of VOC exposure and the impact of outdoor-related air pollution on the indoor environment.2 Methods2.1 Measurement sitesThe study region, La Plata and neighboring areas, located northeast of Buenos Aires province (Argentina), has a population around 700,000 inhabitants. Four sampling zones were considered: industrial (I), urban (U), semi-rural (SR) and residential (R) areas (Figure 1).The industrial area holds the country’s main oil refinery (total crude oil distillation capacity: 38,000 m3/day_1) located next to six petrochemical plants producing diverse compounds such as aromatics (benzene, toluene, xylenes), aliphatic solvents (n-pentane, n-hexane, n-heptane), polypropylene, polybutene, WIT Transactions on Ecology and the Environment, Vol 116, © 2008 WIT Presswww.witpress.com, ISSN 1743-3541 (on-line)Air Pollution XVI 469maleic anhydride, cyclohexane, methanol, methyl tertiary butyl ether, and petroleum coke. This industrial complex is approximately 10 km north-northeast of the main urban sector of the city.The urban area is characterized by heavy traffic; the number of vehicles registered is approximately 200,000. The semi-rural and residential sites, places with low traffic, were considered control areas.Figure 1 : Sampling points in La Plata (I, industrial; U, urban; SR, semi- rural; R, residential).Figure 2: Sampling points in Mexico (TOurban, T1 suburban, T2 rural).WTT Transactions on Ecology and the Environment, Vol 116, © 2008 WIT Presswww.witpress.com, ISSN 1743-3541 (on-line)470 Air Pollution XVIThe Mexico study is part of the MIL AGRO project (Megacity Initiative: Local and Global Research Observations) [16], The air pollution problem in megacities is influenced by several factors that include the topography, meteorology, demographic growth, industrial growth and urban expansion.The Mexico City Metropolitan Area (MCMA) - the second largest megacity in the world - has an estimated population of 18 million people and covers an urbanized area that totals 1,500 km2, encompassing the 16 delegations of the Federal District, 37 municipalities of the State of Mexico and 1 municipality of the State of Hidalgo. In the MCMA, emissions of pollutants reach millions of tons per year, and atmospheric concentrations of ozone and particulate matter routinely exceed the standards recommended by the World Health Organization[6],  As a result, there has been an increase in diagnosed incidences of chronic bronchitis, asthma, reduction of pulmonary capacity, and in premature mortality rates among the citizens. The study region, Mexico City and the neighboring areas in main wind direction (SW to NE) includes three different sites (TO, Tl, T2): TO - within MCMA located at Iztapalapa, Tl - at the Universidad Tecnologica de Tecamac in the State of Mexico, T2 in Rancho La Bisnaga, north of Tizayuca in the State of Hidalgo (Figure 2). The designations refer to transport of the urban plume to different points in space and time. The selected VOC represent alkanes, cycloalkanes and aromatics, chloroaromatics, terpenes.2.2 Sampling design and measurement methodSampling was carried out in indoor and outdoor air using passive sampler (3M OVM 3500, 1986) [14], A sampling period of four weeks was selected, since an integrative sampling described a mean load relative to personal exposure. Using this procedure, it can be assumed that the human exposure is more selectively described compared with a short time measurement. Indoor samples were collected in kindergartens, schools, offices and in the selected homes of children, while outdoor samples were collected in representative sites parallel to the indoor measurement. The outdoor monitors were placed at rain-protected positions. Indoors, the passive monitors were placed in the middle of the room at a 1.5-2 m height with a minimum distance of 50 cm to the ceiling [7, 15],According to their structure and composition the VOC belong to the following groups: alkanes (hexane, heptane, octane, nonane, decane, undecane, dodecane, tridecane); cycloalkanes (methylcyclopentane, cyclohexane, methylcyclohexane); aromatic hydrocarbons (benzene, toluene, ethylbenzene, m+p-xylene, styrene, o-xylene, 4-ethyltoluene, 3-ethyltoluene, 2-ethyltoluene, naphthalene); chlorinated hydrocarbons (chlorbenzene, trichlorethylene, tetrachlorethylene); terpenes (a-pinene, b-pinene, 2-carene, 3-carene, limonene).After exposure, the VOCs were desorbed from the adsorption layers (charcoal pads) by means of 1.5 ml of carbon disulfide (with low benzene, from Merck) containing 1% of methanol. The VOC analysis was performed on a PerkinElmer gas chromatograph with a masspectrometrical detector, equipped with an RTX-1 column (60 m 0.32 mm I.D., 1.0 pm film thickness; Restek). The oven temperature was held at 43 °C for 5 min, and then programmed to 200 °C at a rate of 2.5 °C min1. The injector temperature was held at 250 °C as well as the WIT Transactions on Ecology and the Environment, Vol 116, © 2008 WIT Presswww.witpress.com, ISSN 1743-3541 (on-line)Air Pollution XVI 471transfer line temperature. An electron energy of 70 eV was used for ionization. The source temperature was held at 200 °C. A sample volume of 1 pl was splitless injected. Integrated areas of selected fragment ions from each of the 29 VOCs were obtained with the software Turbomass, Version 4.4 (PerkinElmer) [7, 10],2.3 Quantification and statistical analysisRecovery coefficients were determined by direct injection of a known amount of the standard into a 3M sampler and subsequent extraction with carbon disulfide containing 1% methanol. The recovery was between 98% and 102%. For the studied VOCs, the background amounts contained in the monitors and in the carbon disulfide were determined for each charge of the samplers and chemicals and were subtracted from the sample results. The detection limits for the components were estimated as the three-fold standard deviation of five replicate measurements of monitor blanks. For components with blank values too low to be registered, it is usual practice to use the three-fold standard deviation of replicate measurements of a low-level standard solution [15], The average concentration of each component over the sampling interval (in pg m-3) was calculated according to the equation adopted from 3M [14], using the adsorption coefficients in charcoal. The detection limits were found to be between 0.01 and 0.05 mg m-3 regarding a sampling interval of 4 weeks.A non-parametric method (Mann-Whitney U-Test) was used for statistical analysis of results, according to the non-symmetrical distribution of the data. Statistical analysis and plots of median values were prepared using Statistica 7.1[17] , A p-valuc below 0.05 was regarded to be statistically significant.3 Results and discussion3.1 Total VOCs loadThe concentration levels of the total indoor and outdoor VOC content per study area is shown in Figure 3a and 3b.Significantly higher concentrations of indoor VOCs were observed independent from the study and local area.3.2 Indoor-outdoor ratioSince most people spend over 80 percent of their time indoors [10], indoor VOCs are thought to be of greater concern considering potential health effects because the indoor concentrations of these compounds are often higher than those typically encountered outdoors. On the one hand the indoor-outdoor ratio (I/O) is generally used to infer penetration to indoor environments and indoor sources[18] , On the other hand this ratio will be determined also by the use of the buildings. It makes a difference whether the building is mainly used for apartments or for public demands. An I/O ratio lower and close to one indicates WIT Transactions on Ecology and the Environment, Vol 116, © 2008 WIT Presswww.witpress.com, ISSN 1743-3541 (on-line)472 Air Pollution XVImore outdoor sources. Significant differences between indoor and outdoor concentrations indicate mainly indoor sources for the VOC compounds.The I/O ratio of the apartments in the urban and suburban areas is similar (between 2.5 and 2.7).The ratio is lower for the schools/offices than for the apartments. This reflects the lower indoor exposure in the public building coming from a reduced use of indoor exposure causing materials and maybe from a reduced redecoration activity but a better air exchange rate.□ indoor□ outdoor(a)□ indoor□ outdoor(b)Figure 3: (a) Indoor and outdoor concentration of VOC (sum of measuredVOC) in La Plata and surroundings (mean values), (b) Indoor and outdoor concentration of VOC (sum of measured VOC) in different building types in Mexico City and surroundings (mean values).WIT Transactions on Ecology and the Environment, Vol 116, © 2008 WIT Presswww.witpress.com, ISSN 1743-3541 (on-line)Air Pollution XVI 473The main sources are the industrial complex and the traffic. The highest outdoor exposure was measured in the industrial area of La Plata following by the traffic dominated exposure in the urban area of Mexico City. The lowest load was recorded in the mral respectively semi-rural sites of both study areas.4 ConclusionsAmbient air in the vicinity of the industrial and urban site is significantly different than the air quality found in the semi-rural and suburban residential areas. Whereas traffic was identified as the main source of outdoor VOC exposure in the urban and residential areas, in the industrial area, outdoor as well indoor air is strongly affected by emissions of the local industry.Total VOCs in the urban, residential and semi-rural areas are equivalent to those reported for other major cities worldwide, indicating comparable burdens, although non-equivalent distribution patterns could be a result of different lifestyles and habits.Indoor/outdoor ratios suggest higher indoor burdens in all places and demonstrate an exceptional importance of indoor exposure.The high outdoor VOC content in the industrial and “high” traffic loaded area, together with the lifestyle quality, very strongly affected the indoor exposure for these inhabitants.Further research will be necessary to evaluate the environmental impact of VOCs and the assessment of effects of the different volatile compounds on human health.AcknowledgementsParts of this study were supported by the International Bureau of the German Federal Ministry of Education and Research, the Secretary of Science and Technology and Province Research Council of the Province of Buenos Aires (CICPBA), the National Research Council of Argentina (CONICET), the Metropolitan Environmental Commission of México City and the Molina Center for Energy and the Environment. The authors would also like to thank Brigitte Winkler for her excellent assistance in the chemical analyses, and Jephte Cruz for her assistance during the monitoring.References[1] WHO (World Health Organization). Protection of the Human Environment. The health effects of indoor air pollution exposure in developing countries, Geneva, 2004.[2] Brown, S.K. Volatile organic compounds in new and established buildings in Melbourne, Australia. Indoor Air. 12:55-63, 2002.[3] Tovalin, H., Whitehead, L. Personal exposure to volatile organic compounds among outdoor and indoor workers in two Mexican cities. Science of the Total Environment. 376, 60-71, 2007.WIT Transactions on Ecology and the Environment, Vol 116, © 2008 WIT Presswww.witpress.com, ISSN 1743-3541 (on-line)474 Air Pollution XVI[4] Herbarth, O., Rehwagen, M., Ronco, A. The Influence of Localized Emittants on the Concentration of Volatile Organic Compounds in the Ambient Air Measured Close to Ground Level. Environ Toxicol Water Qual. 12:31-37, 1997.[5] Chan, C., Chan, L., Wang, X., Liu, Y., Lee, Y., Zou, S., Sheng, G., Fu, J. Volatile organic compounds in roadside microenvironments of metropolitan Hong Kong. Atmos Environ. 36 (12):2039-2047, 2002.[6] SMA - Secretaria del Medio Ambiente. Inventario de contaminantes tóxicos del aire en la ZMVM (MCMA Air toxics inventory). Gobierno del Distrito Federal. México. 2006.[7] Rehwagen, M., Schlink, U., Herbarth, O. Seasonal cycle of VOCs in apartments. Indoor Air 13:1-9, 2003.[8] Guo, H., Lee, S., Chan, L., Li, W. Risk assessment of exposure to volatile organic compounds in different indoor environments. Environ Res. 94:57- 66, 2004.[9] Son, B., Breysse, P., Yang, W. Volatile organic compounds concentration in residential indoor and outdoor and its personal exposure in Korea. EnvironInt. 29:79-85,2003.[10] Schlink, U., Rehwagen, M., Damm, M., Richter, M., Borte, M., Herbarth, O. Seasonal cycle of indoor-VOCs: comparison of apartments and cities. Atmos Environ. 38: 1181-1190, 2004.[11] Jones, A. Indoor air quality and health. Atmos Environ. 33:4535-4564, 1999.[12] Watson, J., Chow, J., Fujita, E. Review of volatile organic compound source apportionment by chemical mass balance. Atmos Environ. 35:1567- 1584, 2001.[13] Guo, H., Lee, S., Li, W., Cao, J. Source characterization of BTEX in indoor microenvironments in Hong Kong. Atmos Environ. 37:73-82, 2003.[14] 3M Deutschland GmbH Technische Informationen 3M Monitore, 1986[15] Begerow J, Jermann E, Kelles T, Ranft U, Dunemann L. Passive sampling for Volatile Organic Compounds (VOCs) in air at environmentally relevant concentration levels. Fresenius Journal of Analytical Chemistry 351: 549- 554, 1995.[16] MILAGRO-Factsheet 2006: http://www.eol.ucar.edu/projects/milagro/ media/MILAGRO-Factsheet-Final.pdf[17] StatSoft, Inc. (2005). STATISTICA fiir Windows [Software-System fiir Datenanalyse] Version 7.1. www.statsoft.com[18] Tang, J., Chan, C.Y., Wang, X., Chan, L.Y., Sheng, G., Fu, J. Volatile organic compounds in a multi-storey shopping mall in Guangzhou, South China. Atmos Environ. 39:7374-7383, 2005.WIT Transactions on Ecology and the Environment, Vol 116, © 2008 WIT Presswww.witpress.com, ISSN 1743-3541 (on-line)

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Comparative study of indoor-outdoor exposure against volatile organic compounds in South and Middle America

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