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Tijdens de opfok van vleeskuikenouderdieren heeft het Praktijkonderzoek Pluim-veehouderij (PP) 'Het Spelderholt' onderzoek gedaan naar het gebruik van de spinfeeder. Hierbij moeten de dieren het voer uit het strooisel pikken. Het voedselzoekgedrag wordt door deze manier van voerverstrekken gestimuleerd, maar er wordt ook veel stof in de stal in beweging gebracht. Gevolg hiervan zijn hoge stofconcentraties.

Tijdens de internationale conferentie DustConf 2007 te Maasticht (23 en 24 april) presenteerden wetenschappers uit diverse landen hun nieuwste manieren om de uitstoot van fijn stof te verminderen

Na een inventarisatie naar de verschillende mogelijkheden om de stofconcentratie in de stallucht te verlagen (zie periodiek 97/4), is in een eerste oriënterende proef gekeken naar het effect van het vernevelen van water. Dit bleek slechts een minimaleverlaging te geven. In dit artikel gaan we in op een vervolgproef waarbij olie is toegevoegd aan het water.

This brochure describes the underlying principles that form a basis for better-informed choices with regards to the management of trees and shrubs in cities and the design of functional planting schemes.

This brochure describes the underlying principles that form a basis for better-informed choices with regards to the management of trees and shrubs in cities and the design of functional planting schemes. Mogelijkheden ter bestrijding van fijnstof

Tijdens de internationale conferentie DustConf 2007 te Maasticht (23 en 24 april) presenteerden wetenschappers uit diverse landen hun nieuwste manieren om de uitstoot van fijn stof te verminderen

Tijdens de internationale conferentie DustConf 2007 te Maasticht (23 en 24 april) presenteerden wetenschappers uit diverse landen hun nieuwste manieren om de uitstoot van fijn stof te verminderen

De agrarische sector draagt naar schatting ongeveer 20% bij aan de primaire emissie van fijn stof in Nederland, waarbij de intensieve veehouderij (varkens en pluimvee) de belangrijkste bronnen zijn. De doelstelling van deze deskstudie was om vast te stellen welke processen en factoren van invloed zijn op stofvorming en emissies in de veehouderij. Tevens is aangegeven hoe deze processen en factoren kunnen worden beïnvloed om de emissie van fijn stof te reduceren

De agrarische sector draagt naar schatting ongeveer 20% bij aan de primaire emissie van fijn stof in Nederland, waarbij de intensieve veehouderij (varkens en pluimvee) de belangrijkste bronnen zijn. De doelstelling van deze deskstudie was om vast te stellen welke processen en factoren van invloed zijn op stofvorming en emissies in de veehouderij. Tevens is aangegeven hoe deze processen en factoren kunnen worden beïnvloed om de emissie van fijn stof te reduceren

De aanwezigheid van fijn stof (deeltjes kleiner dan 10 ~S^~m) in de buitenlucht kan gezondheidsproblemen veroorzaken. Om deze reden zijn in EU-verband normen voor fijn stof gesteld. Voor het bestrijden van de emissie van fijn stof is het van belang om deomvang van de verschillende bronnen te kennen. Over de emissie vanuit de landbouw bestond een aantal onduidelijkheden. De afdeling Monitoring en Informatiemanagement van het Ministerie van VROM heeft een opdracht gegeven aan Alterra om in samenwerking met RIVM de methodiek van emissieschatting te verbeteren. Het project heeft bestaan uit literatuuronderzoek en het bespreken van de problematiek met een aantal deskundigen tijdens een discussiedag. Uit het onderzoek blijkt dat stallen waarschijnlijk de grootste emissiebron vormen van fijn stof vanuit de landbouw. Daarnaast is er een aantal relatief kleine posten, met als belangrijkste de toediening van bestrijdingsmiddelen en kunstmest en de aanvoer van krachtvoer op het agrarisch bedrijf. Winderosie is vermoedelijk ook een grote bron, die variabel is in de tijd. De omvang ervan is echter moeilijk te schatten.

De aanwezigheid van fijn stof (deeltjes kleiner dan 10 ~S^~m) in de buitenlucht kan gezondheidsproblemen veroorzaken. Om deze reden zijn in EU-verband normen voor fijn stof gesteld. Voor het bestrijden van de emissie van fijn stof is het van belang om deomvang van de verschillende bronnen te kennen. Over de emissie vanuit de landbouw bestond een aantal onduidelijkheden. De afdeling Monitoring en Informatiemanagement van het Ministerie van VROM heeft een opdracht gegeven aan Alterra om in samenwerking met RIVM de methodiek van emissieschatting te verbeteren. Het project heeft bestaan uit literatuuronderzoek en het bespreken van de problematiek met een aantal deskundigen tijdens een discussiedag. Uit het onderzoek blijkt dat stallen waarschijnlijk de grootste emissiebron vormen van fijn stof vanuit de landbouw. Daarnaast is er een aantal relatief kleine posten, met als belangrijkste de toediening van bestrijdingsmiddelen en kunstmest en de aanvoer van krachtvoer op het agrarisch bedrijf. Winderosie is vermoedelijk ook een grote bron, die variabel is in de tijd. De omvang ervan is echter moeilijk te schatten.

Varkenshouders hebben relatief veel respiratoire klachten, wat voor een belangrijk deel wordt toegeschreven aan de luchtkwaliteit in de stallen. Een van de risicofactoren die deze klachten kunnen veroorzaken is het stof dat doorgaans in stallucht aanwezig is. Het voer en de voermethode hebben veel invloed op de stofconcentratie in stallen. Daarom is in de stal voor gespeende biggen op het varkensproefbedrijf in Rosmalen in 1994 en 1999 onderzoek verricht naar de invloed van het afdekken van droogvoerbakken op de stofconcentratie in de stallucht. De vulopening van de voerbakken werd afgedekt met een plaat waar de vulpijpen van de voerinstallatie precies doorheen pasten. Uit het onderzoek blijkt dat het afdekken van de voerbakken geen significante invloed heeft op de gemiddelde concentraties inhaleerbaar stof

Tijdens de opfok van vleeskuikenouderdieren heeft het Praktijkonderzoek Pluim-veehouderij (PP) 'Het Spelderholt' onderzoek gedaan naar het gebruik van de spinfeeder. Hierbij moeten de dieren het voer uit het strooisel pikken. Het voedselzoekgedrag wordt door deze manier van voerverstrekken gestimuleerd, maar er wordt ook veel stof in de stal in beweging gebracht. Gevolg hiervan zijn hoge stofconcentraties.

Tijdens de opfok van vleeskuikenouderdieren heeft het Praktijkonderzoek Pluim-veehouderij (PP) 'Het Spelderholt' onderzoek gedaan naar het gebruik van de spinfeeder. Hierbij moeten de dieren het voer uit het strooisel pikken. Het voedselzoekgedrag wordt door deze manier van voerverstrekken gestimuleerd, maar er wordt ook veel stof in de stal in beweging gebracht. Gevolg hiervan zijn hoge stofconcentraties.

Varkenshouders hebben relatief veel respiratoire klachten, wat voor een belangrijk deel wordt toegeschreven aan de luchtkwaliteit in de stallen. Een van de risicofactoren die deze klachten kunnen veroorzaken is het stof dat doorgaans in stallucht aanwezig is. Het voer en de voermethode hebben veel invloed op de stofconcentratie in stallen. Daarom is in de stal voor gespeende biggen op het varkensproefbedrijf in Rosmalen in 1994 en 1999 onderzoek verricht naar de invloed van het afdekken van droogvoerbakken op de stofconcentratie in de stallucht. De vulopening van de voerbakken werd afgedekt met een plaat waar de vulpijpen van de voerinstallatie precies doorheen pasten. Uit het onderzoek blijkt dat het afdekken van de voerbakken geen significante invloed heeft op de gemiddelde concentraties inhaleerbaar stof

In Denemarken is een internationaal symposium gehouden met als thema stof in stallen. De huidige houderijvormen in de intensieve veehouderij worden over de hele wereld gezien als een ernstige bedreiging voor de gezondheid van degenen die in de stallenwerken

In Denemarken is een internationaal symposium gehouden met als thema stof in stallen. De huidige houderijvormen in de intensieve veehouderij worden over de hele wereld gezien als een ernstige bedreiging voor de gezondheid van degenen die in de stallenwerken

This thesis discusses properties of ambient aerosols in the Netherlands which are controlling the magnitude of the local aerosol radiative forcing. Anthropogenic aerosols influence climate by changing the radiative transfer through the atmosphere via two effects, one is direct and a second is indirect. Due to the scattering of solar light on aerosol particles the Earth surface receives less radiation and thus cools, which is called the direct aerosol effect.The indirect effect includes processes by which aerosols influence the radiation balance indirectly - via clouds. The indirect effect includes mechanisms by which anthropogenic aerosol particles enhance the reflectivity and prolong the life time of marine stratoform clouds by increasing their droplet number concentration. Anthropogenic aerosols were demonstrated to have a considerable cooling effect on climate, comparable in magnitude to that of the greenhouse gases, but opposite in sign. However, calculation of the aerosol radiative forcing is much more complex than that for the green house gases. This results in high uncertainties in the estimates of the effects of anthropogenic aerosols on climate.Both types of the aerosol radiative forcing and their magnitude, as estimated by the Intergovernmental Panel on Climate Change (IPCC), are discussed in Chapter 1. The aerosol radiative forcing is a regional phenomenon because of the limited life time of aerosols in the atmosphere. Thus, the aerosol effects should be assessed locally.In Chapter 2 chemical composition of local ambient aerosols in the size range relevant to the radiative forcing is discussed. It is shown that ammonium nitrate, which is omitted by the IPCC, is a major contributor to the direct, and perhaps to the indirect forcing. The contribution of this compound to the local direct forcing is equal to that of anthropogenic sulfate aerosols. Measurements of ammonium nitrate content in submicrometer aerosol are subject to artifacts due to the volatility of this compound. Automated techniques which were developed for artifact-free measurements of chemical composition of ambient aerosols are described.Aerosol particles composed of water-soluble salts increase their size at elevated relative humidities. The increase in size enhances light scattering by aerosol particles which in turn enhances the direct radiative forcing. Hygroscopic properties of aerosol particles also play a central role in cloud droplet formation and thus are also relevant for the indirect aerosol effect. Chapter 2 discusses the hygroscopic size changes and characteristic growth times. It is also demonstrated that hygroscopic growth may substantially enhance dry deposition of aerosol particles to forests.According to the IPCC the indirect aerosol effect is the most uncertain factor in the anthropogenic perturbation of the climate, with an uncertainty of the same magnitude as the total radiative effect by the greenhouse gases. One of the major uncertainties in the indirect effect is the unknown relation between the concentration of anthropogenic aerosol particles and the increase in droplet number concentration in clouds. In Europe only few measurements of the relation between the number of particles and the number of cloud droplets have been performed.It should be also noted that those measurements were performed with instruments that did not span the full range of aerosol sizes that is relevant for cloud formation. For this reason, the major part of the thesis was devoted to an experimental assessment of the cloud forming properties of ambient aerosol in the Netherlands. The indirect effect as well as factors controlling cloud droplet formation are discussed in Chapter 3.Chapter 4 describes the large flow-through cloud chamber in which cloud forming properties of ambient aerosol were studied. The advantage of a cloud chamber over in-situ measurements is the use of instrumentation which is too delicate for use in aircraft and the possibility to compare, simultaneously, the aerosol before and after cloud processing. The aerosol was characterized both in terms of its number concentration and size as well as its chemical composition with the emphasis on the amount of soluble material. The unique feature of the cloud chamber is its reproducible stable low supersaturations (around 0.1%) common for marine clouds.Aerosol monitors were used that measure the concentration of particles in the full range of sizes relevant for cloud formation. The unique large size and the high throughput flow of the chamber allowed unperturbed use of conventional cloud instrumentation for sizing and counting of droplets. Also high-flow cascade impactors for chemical analysis of aerosol were used. The cloud chamber was calibrated with artificially generated ammonium sulfate aerosol. This aerosol was selected because in anthropogenically influenced air in Western Europe most particles should consist of this compound. Experiments were done at different total aerosol number concentrations to check its influence on the number of resulting cloud droplets. A sub-linear relation between the aerosol and the droplet number concentrations was observed. The results of the tests with the reference aerosol were used for the interpretation of experiments with ambient aerosols.The cloud activation tests on ambient aerosol are discussed in Chapter 5. The cloud forming efficiency of the aerosols was assessed by comparing the number concentration of droplets formed in the cloud chamber with that found during the tests with the reference ammonium sulfate aerosol at the same number concentration. Similarly to the reference sulfate aerosol, a sub-linear relation between the aerosol and droplet number concentrations was observed. However, the deviation from a linear relation was stronger in the ambient aerosol. This suggested that about one third of the (anthropogenic) particles was water-insoluble. The measurements of the composition supported this hypothesis. This demonstrates the importance of hygroscopicity for cloud formation. It also shows that measurements of the solubility of (individual) particles should be done along with conventional measurements of aerosol size and number.The results of experiments discussed in Chapter 5 were used for an estimate of the local indirect aerosol radiative effect (Chapter 6). The difference between the droplet number concentration in clean marine air and the average droplet number concentration in polluted air was used to estimate the corresponding increase in cloud reflectivity which, in turn, was translated into local indirect aerosol effect. The data on the aerosol light scattering discussed in Chapter 2 are used to estimate the local direct radiative forcing. The estimated total (direct plus indirect) local aerosol radiative forcing is about 4 times higher than the forcing by the anthropogenic greenhouse gases but opposite in sign.

This thesis discusses properties of ambient aerosols in the Netherlands which are controlling the magnitude of the local aerosol radiative forcing. Anthropogenic aerosols influence climate by changing the radiative transfer through the atmosphere via two effects, one is direct and a second is indirect. Due to the scattering of solar light on aerosol particles the Earth surface receives less radiation and thus cools, which is called the direct aerosol effect.The indirect effect includes processes by which aerosols influence the radiation balance indirectly - via clouds. The indirect effect includes mechanisms by which anthropogenic aerosol particles enhance the reflectivity and prolong the life time of marine stratoform clouds by increasing their droplet number concentration. Anthropogenic aerosols were demonstrated to have a considerable cooling effect on climate, comparable in magnitude to that of the greenhouse gases, but opposite in sign. However, calculation of the aerosol radiative forcing is much more complex than that for the green house gases. This results in high uncertainties in the estimates of the effects of anthropogenic aerosols on climate.Both types of the aerosol radiative forcing and their magnitude, as estimated by the Intergovernmental Panel on Climate Change (IPCC), are discussed in Chapter 1. The aerosol radiative forcing is a regional phenomenon because of the limited life time of aerosols in the atmosphere. Thus, the aerosol effects should be assessed locally.In Chapter 2 chemical composition of local ambient aerosols in the size range relevant to the radiative forcing is discussed. It is shown that ammonium nitrate, which is omitted by the IPCC, is a major contributor to the direct, and perhaps to the indirect forcing. The contribution of this compound to the local direct forcing is equal to that of anthropogenic sulfate aerosols. Measurements of ammonium nitrate content in submicrometer aerosol are subject to artifacts due to the volatility of this compound. Automated techniques which were developed for artifact-free measurements of chemical composition of ambient aerosols are described.Aerosol particles composed of water-soluble salts increase their size at elevated relative humidities. The increase in size enhances light scattering by aerosol particles which in turn enhances the direct radiative forcing. Hygroscopic properties of aerosol particles also play a central role in cloud droplet formation and thus are also relevant for the indirect aerosol effect. Chapter 2 discusses the hygroscopic size changes and characteristic growth times. It is also demonstrated that hygroscopic growth may substantially enhance dry deposition of aerosol particles to forests.According to the IPCC the indirect aerosol effect is the most uncertain factor in the anthropogenic perturbation of the climate, with an uncertainty of the same magnitude as the total radiative effect by the greenhouse gases. One of the major uncertainties in the indirect effect is the unknown relation between the concentration of anthropogenic aerosol particles and the increase in droplet number concentration in clouds. In Europe only few measurements of the relation between the number of particles and the number of cloud droplets have been performed.It should be also noted that those measurements were performed with instruments that did not span the full range of aerosol sizes that is relevant for cloud formation. For this reason, the major part of the thesis was devoted to an experimental assessment of the cloud forming properties of ambient aerosol in the Netherlands. The indirect effect as well as factors controlling cloud droplet formation are discussed in Chapter 3.Chapter 4 describes the large flow-through cloud chamber in which cloud forming properties of ambient aerosol were studied. The advantage of a cloud chamber over in-situ measurements is the use of instrumentation which is too delicate for use in aircraft and the possibility to compare, simultaneously, the aerosol before and after cloud processing. The aerosol was characterized both in terms of its number concentration and size as well as its chemical composition with the emphasis on the amount of soluble material. The unique feature of the cloud chamber is its reproducible stable low supersaturations (around 0.1%) common for marine clouds.Aerosol monitors were used that measure the concentration of particles in the full range of sizes relevant for cloud formation. The unique large size and the high throughput flow of the chamber allowed unperturbed use of conventional cloud instrumentation for sizing and counting of droplets. Also high-flow cascade impactors for chemical analysis of aerosol were used. The cloud chamber was calibrated with artificially generated ammonium sulfate aerosol. This aerosol was selected because in anthropogenically influenced air in Western Europe most particles should consist of this compound. Experiments were done at different total aerosol number concentrations to check its influence on the number of resulting cloud droplets. A sub-linear relation between the aerosol and the droplet number concentrations was observed. The results of the tests with the reference aerosol were used for the interpretation of experiments with ambient aerosols.The cloud activation tests on ambient aerosol are discussed in Chapter 5. The cloud forming efficiency of the aerosols was assessed by comparing the number concentration of droplets formed in the cloud chamber with that found during the tests with the reference ammonium sulfate aerosol at the same number concentration. Similarly to the reference sulfate aerosol, a sub-linear relation between the aerosol and droplet number concentrations was observed. However, the deviation from a linear relation was stronger in the ambient aerosol. This suggested that about one third of the (anthropogenic) particles was water-insoluble. The measurements of the composition supported this hypothesis. This demonstrates the importance of hygroscopicity for cloud formation. It also shows that measurements of the solubility of (individual) particles should be done along with conventional measurements of aerosol size and number.The results of experiments discussed in Chapter 5 were used for an estimate of the local indirect aerosol radiative effect (Chapter 6). The difference between the droplet number concentration in clean marine air and the average droplet number concentration in polluted air was used to estimate the corresponding increase in cloud reflectivity which, in turn, was translated into local indirect aerosol effect. The data on the aerosol light scattering discussed in Chapter 2 are used to estimate the local direct radiative forcing. The estimated total (direct plus indirect) local aerosol radiative forcing is about 4 times higher than the forcing by the anthropogenic greenhouse gases but opposite in sign.

Na een inventarisatie naar de verschillende mogelijkheden om de stofconcentratie in de stallucht te verlagen (zie periodiek 97/4), is in een eerste oriënterende proef gekeken naar het effect van het vernevelen van water. Dit bleek slechts een minimaleverlaging te geven. In dit artikel gaan we in op een vervolgproef waarbij olie is toegevoegd aan het water.

Na een inventarisatie naar de verschillende mogelijkheden om de stofconcentratie in de stallucht te verlagen (zie periodiek 97/4), is in een eerste oriënterende proef gekeken naar het effect van het vernevelen van water. Dit bleek slechts een minimaleverlaging te geven. In dit artikel gaan we in op een vervolgproef waarbij olie is toegevoegd aan het water.

Het Praktijkonderzoek Pluimveehouderij 'Het Spelderholt' (PP) en het Instituut voor Milieu-en Agritechniek (IMAG-DLO) hebben gezamenlijk onderzoek opgestart naar verlaging van de stofconcentratie in pluimveestallen. Dit heeft geresulteerd in het project 'Effecten van het vernevelen van vloeistoffen ter verlaging van de stofconcentratie in pluimveestallen'. Op basis van een literatuurstudie is binnen dit project gekozen om het terugdringen van de stofconcentratie in pluimveestallen door middel van hetvernevelen van vloeistoffen nader te bekijken.

Het Praktijkonderzoek Pluimveehouderij 'Het Spelderholt' (PP) en het Instituut voor Milieu-en Agritechniek (IMAG-DLO) hebben gezamenlijk onderzoek opgestart naar verlaging van de stofconcentratie in pluimveestallen. Dit heeft geresulteerd in het project 'Effecten van het vernevelen van vloeistoffen ter verlaging van de stofconcentratie in pluimveestallen'. Op basis van een literatuurstudie is binnen dit project gekozen om het terugdringen van de stofconcentratie in pluimveestallen door middel van hetvernevelen van vloeistoffen nader te bekijken.

Om de uitstoot van ammoniak uit pluimveestallen te beperken kunnen een aantal maatregelen worden genomen. Bijvoorbeeld het toepassen van droge luchtwassers. Voor het wassen van de lucht wordt bij droge wassers de stallucht door filtermateriaal gezogen of geblazen. Het filtermateriaal moet de ammoniak absorberen. Deze wijze van luchtwassen kan worden toegepast bij de lucht die via de ventilatoren wordt afgezogen. Bij droge luchtwassers is het ook mogelijk om de stallucht te circuleren en te wassen, zonder dat dit een nadelig effect heeft op de relatieve luchtvochtigheid in de stal. Momenteel wordt in de pluimveehouderij het droog wassen van stallucht nauwelijks toegepast. Er is dan ook weinig bekend over het absorptievermogen van droge luchtwassers in pluimveestallen. Stallucht in pluimveestallen is nogal stoffig en het is niet bekend of dit stof de werking van droge luchtwassers beïnvloedt. In samenwerking met de provincie Gelderland is bij het Pluimvee Praktijkonderzoek onderzoek uitgevoerd naar de werking van droge luchtwassers in een vieeskuikenouderdierenstal. In dit verslag worden de resultaten van dit onderzoek besproken

Om de uitstoot van ammoniak uit pluimveestallen te beperken kunnen een aantal maatregelen worden genomen. Bijvoorbeeld het toepassen van droge luchtwassers. Voor het wassen van de lucht wordt bij droge wassers de stallucht door filtermateriaal gezogen of geblazen. Het filtermateriaal moet de ammoniak absorberen. Deze wijze van luchtwassen kan worden toegepast bij de lucht die via de ventilatoren wordt afgezogen. Bij droge luchtwassers is het ook mogelijk om de stallucht te circuleren en te wassen, zonder dat dit een nadelig effect heeft op de relatieve luchtvochtigheid in de stal. Momenteel wordt in de pluimveehouderij het droog wassen van stallucht nauwelijks toegepast. Er is dan ook weinig bekend over het absorptievermogen van droge luchtwassers in pluimveestallen. Stallucht in pluimveestallen is nogal stoffig en het is niet bekend of dit stof de werking van droge luchtwassers beïnvloedt. In samenwerking met de provincie Gelderland is bij het Pluimvee Praktijkonderzoek onderzoek uitgevoerd naar de werking van droge luchtwassers in een vieeskuikenouderdierenstal. In dit verslag worden de resultaten van dit onderzoek besproken

The mutagenicity of indoor and outdoor airborne particulate matter (APM) has been demonstrated by previous in vitro studies (Alink et al., 1983; Van Houdt et al., 1984, 1986, 1987). The aim of the present thesis was to contribute to a better understanding of the mode of action of AIM in the pathogenesis of lung cancer by expanding the scope to the in vivo initiating (Chapter 3 and 4), tumor promoting (Chapter 5 and 6) and carcinogenic (Chapter 7) potential of APM.The aromatic DNA adduct level in white blood cells was used as a biomarker for measuring the exposure of man to residential wood combustion particulate matter under conditions which most likely reflect the pattern of use of open fire places in The Netherlands (Chapter 3). Although indoor air mutagenicity and benzo(a)pyrene (BaP) and pyrene levels were increased, no combustionrelated increase in the amount of adducts was observed. This indicates that these levels of aromatic compounds are probably not an important source of genotoxic damage to DNA.In Chapter 4 experiments are described in which outdoor as well as indoor AIM extracts were tested for in vivo genotoxicity in the DNA-repair host-mediated assay. Although the APM extracts were genotoxic in vitro, high doses of APM induced no genotoxic activity in mice. Because polycyclic aromatic hydrocarbons (PAHs) and nitroPAHs are known to contribute to the mutagenicity of APM, BaP and 2-nitrofluorene (NF) were used as positive controls. High concentrations of BaP caused a moderate effect in mice whereas NF was not genotoxic at all in vivo. It was concluded that the DNA-repair host-mediated assay is (relative) insensitive for PAHs and nitroPAHs. In addition, deactivation of APM in vivo might be responsible for the lack of genotoxicity observed.Because it is generally accepted that carcinogenesis is a multi-step process we also studied the tumor promoting potential of APM. Inhibition of gap-junctional intercellular communication (GJIC) was used for measuring tumor promoting effects (Chapter 5). We showed that outdoor as well as indoor APM strongly inhibited GJIC in V79 Chinese hamster lung fibroblasts. Mutagenicity data, obtained with Salmonella typhimurium TA 98, and the data on inhibition of GJIC were correlated, and the concentrations at which a positive effect was found, were in the same range. V79 cells lack the capacity to metabolize foreign compounds. Thus the effects on communication were caused by unmetabolized compounds. We also showed that communication was strongly inhibited in primary cultures of rat alveolar type II cells, a target cell for inhaled particles. Type II cells do have the capacity to metabolize foreign compounds, but it is unknown whether parent compounds and/or their metabolites inhibited IC.Because vitamin A is an important regulator of normal epithelial differentiation and proliferation and a disturbance in its kinetics might influence the process of carcinogenesis, interactions of APM with the kinetics of vitamin A were studied (Chapter 6). A single high dose of APM extract increased plasma retinol levels in rats whereas lung vitamin A levels were depleted. Such a depletion might indicate an increased susceptibility for the development of lung tumors.Finally, the carcinogenicity of outdoor APM in the newborn mouse bioassay was studied (Chapter 7). The APM samples were taken under conditions of increased air pollution. Because man is exposed to such high pollution levels only for a limited amount of time, the dose levels of APM applied in this animal model were an overestimation compared to the actual cumulative dose man is exposed to. BaP, used as a positive control, significantly increased the lung tumor incidence. On the contrary no evidence was found for a carcinogenic response to APM.In a recent assessment of the state of the art in chemical carcinogenesis by Gori (1992) it is mentioned that initiation may not solely be of a mutagenic nature, but may more reflect a shift of the normal behavior of cells towards an adaptation to stressors adverse to cell and organism homeostasis, mediated by epigenetic events. It is further stated in that study that "initiation may be a trivial step in carcinogenesis, given that all cells in an organism are exposed since embryonic development to multiple initiator stresses, either physiologically generated of from the myriad of naturally ocurring external encounters." The idea of Gori implicates also that the initiating properties of chemicals might be of less importance then generally is assumed. All this would plead for a more important role of tumor promotion in the process of carcinogenesis. For cigarette smoking this indeed seems to be the case. For people who stop smoking the risk freezes at the time of quitting without further advantages, suggesting a promotional role of smoking. Upon smoking cessation the effects of nongenotoxic promoting agents abruptly stop. As a consequence preneoplastic lesions remain static or regress, whereas in the continuing smoker they progress (Doll and Peto, 1978; Weisburger, 1990). Furthermore, from epidemiological data of cigarette smoking and lung cancer it can be concluded that a threshold exists at measurable doses, again pleading for an important role of tumor promotion (Gori and Mantel, 1991).As in the studies described in this thesis no evidence is found for an in vivo initiating or carcinogenic potential of APM, it might be that analogous with cigarette smoke also for APM the tumor promoting potential might be of more importance than the initiating potential. Therefore it is concluded that exposure to APM alone probably does not pose an important cancer risk to man. However, in combination with other factors a contribution of APM to the development of cancer can not be excluded.

The mutagenicity of indoor and outdoor airborne particulate matter (APM) has been demonstrated by previous in vitro studies (Alink et al., 1983; Van Houdt et al., 1984, 1986, 1987). The aim of the present thesis was to contribute to a better understanding of the mode of action of AIM in the pathogenesis of lung cancer by expanding the scope to the in vivo initiating (Chapter 3 and 4), tumor promoting (Chapter 5 and 6) and carcinogenic (Chapter 7) potential of APM.The aromatic DNA adduct level in white blood cells was used as a biomarker for measuring the exposure of man to residential wood combustion particulate matter under conditions which most likely reflect the pattern of use of open fire places in The Netherlands (Chapter 3). Although indoor air mutagenicity and benzo(a)pyrene (BaP) and pyrene levels were increased, no combustionrelated increase in the amount of adducts was observed. This indicates that these levels of aromatic compounds are probably not an important source of genotoxic damage to DNA.In Chapter 4 experiments are described in which outdoor as well as indoor AIM extracts were tested for in vivo genotoxicity in the DNA-repair host-mediated assay. Although the APM extracts were genotoxic in vitro, high doses of APM induced no genotoxic activity in mice. Because polycyclic aromatic hydrocarbons (PAHs) and nitroPAHs are known to contribute to the mutagenicity of APM, BaP and 2-nitrofluorene (NF) were used as positive controls. High concentrations of BaP caused a moderate effect in mice whereas NF was not genotoxic at all in vivo. It was concluded that the DNA-repair host-mediated assay is (relative) insensitive for PAHs and nitroPAHs. In addition, deactivation of APM in vivo might be responsible for the lack of genotoxicity observed.Because it is generally accepted that carcinogenesis is a multi-step process we also studied the tumor promoting potential of APM. Inhibition of gap-junctional intercellular communication (GJIC) was used for measuring tumor promoting effects (Chapter 5). We showed that outdoor as well as indoor APM strongly inhibited GJIC in V79 Chinese hamster lung fibroblasts. Mutagenicity data, obtained with Salmonella typhimurium TA 98, and the data on inhibition of GJIC were correlated, and the concentrations at which a positive effect was found, were in the same range. V79 cells lack the capacity to metabolize foreign compounds. Thus the effects on communication were caused by unmetabolized compounds. We also showed that communication was strongly inhibited in primary cultures of rat alveolar type II cells, a target cell for inhaled particles. Type II cells do have the capacity to metabolize foreign compounds, but it is unknown whether parent compounds and/or their metabolites inhibited IC.Because vitamin A is an important regulator of normal epithelial differentiation and proliferation and a disturbance in its kinetics might influence the process of carcinogenesis, interactions of APM with the kinetics of vitamin A were studied (Chapter 6). A single high dose of APM extract increased plasma retinol levels in rats whereas lung vitamin A levels were depleted. Such a depletion might indicate an increased susceptibility for the development of lung tumors.Finally, the carcinogenicity of outdoor APM in the newborn mouse bioassay was studied (Chapter 7). The APM samples were taken under conditions of increased air pollution. Because man is exposed to such high pollution levels only for a limited amount of time, the dose levels of APM applied in this animal model were an overestimation compared to the actual cumulative dose man is exposed to. BaP, used as a positive control, significantly increased the lung tumor incidence. On the contrary no evidence was found for a carcinogenic response to APM.In a recent assessment of the state of the art in chemical carcinogenesis by Gori (1992) it is mentioned that initiation may not solely be of a mutagenic nature, but may more reflect a shift of the normal behavior of cells towards an adaptation to stressors adverse to cell and organism homeostasis, mediated by epigenetic events. It is further stated in that study that "initiation may be a trivial step in carcinogenesis, given that all cells in an organism are exposed since embryonic development to multiple initiator stresses, either physiologically generated of from the myriad of naturally ocurring external encounters." The idea of Gori implicates also that the initiating properties of chemicals might be of less importance then generally is assumed. All this would plead for a more important role of tumor promotion in the process of carcinogenesis. For cigarette smoking this indeed seems to be the case. For people who stop smoking the risk freezes at the time of quitting without further advantages, suggesting a promotional role of smoking. Upon smoking cessation the effects of nongenotoxic promoting agents abruptly stop. As a consequence preneoplastic lesions remain static or regress, whereas in the continuing smoker they progress (Doll and Peto, 1978; Weisburger, 1990). Furthermore, from epidemiological data of cigarette smoking and lung cancer it can be concluded that a threshold exists at measurable doses, again pleading for an important role of tumor promotion (Gori and Mantel, 1991).As in the studies described in this thesis no evidence is found for an in vivo initiating or carcinogenic potential of APM, it might be that analogous with cigarette smoke also for APM the tumor promoting potential might be of more importance than the initiating potential. Therefore it is concluded that exposure to APM alone probably does not pose an important cancer risk to man. However, in combination with other factors a contribution of APM to the development of cancer can not be excluded.

In this thesis the acute effects of air pollution episodes on respiratory health of seven to eleven year old children living in non-urban communities in the Netherlands are discussed. Repeated measurements of pulmonary function (spirometry) and the occurrence of acute respiratory symptoms using a daily diary, were conducted to detect health effects. Exposure to air pollution was characterized by the ambient concentration of several pollutants, including ozone, PM 10 and acid aerosol, measured at fixed sites. Data were collected for a period of three and a half year, including two summer and three winter periods, from 1851 children.In the summer of 1989 several photochemical episodes occurred with one hour maximum ozone concentrations between 160 and 240μg/m 3. During these episodes small decrements of pulmonary function persisting for at least one day were found. No evidence of increased respiratory symptoms was found during these episodes. No major winter air pollution episode occurred, but significant associations of pulmonary function with the concentration of particles smaller than 10μm (PM 10 ) were found. These associations were not explained by exposure to acid aerosol, because concentration levels of acid aerosol were low during both the winter and the summer periods. For the general population samples of children, respiratory symptom prevalence was not associated with air pollution levels. For a panel of children with chronic respiratory symptoms, prevalence of wheeze and bronchodilator use was associated with the PM 10 concentration. For all study populations differences in pulmonary function response between individual children were found. However, determined characteristics of the children (age, gender, presence of chronic respiratory symptoms) did not explain the magnitude of the response to air pollution.The findings of the present study in combination with other recent studies support a revision of present guidelines for ozone and particulate matter.

Tijdens het voeren met een voerdoseerwagen komt er stof vrij. Met behulp van een stofzuiger op de voerdoseerwagen die het stof bij het afstortpunt wegzuigt, kan het stofgehalte in de stallucht tijdens het voeren gereduceerd worden.

In this thesis the acute effects of air pollution episodes on respiratory health of seven to eleven year old children living in non-urban communities in the Netherlands are discussed. Repeated measurements of pulmonary function (spirometry) and the occurrence of acute respiratory symptoms using a daily diary, were conducted to detect health effects. Exposure to air pollution was characterized by the ambient concentration of several pollutants, including ozone, PM 10 and acid aerosol, measured at fixed sites. Data were collected for a period of three and a half year, including two summer and three winter periods, from 1851 children.In the summer of 1989 several photochemical episodes occurred with one hour maximum ozone concentrations between 160 and 240μg/m 3. During these episodes small decrements of pulmonary function persisting for at least one day were found. No evidence of increased respiratory symptoms was found during these episodes. No major winter air pollution episode occurred, but significant associations of pulmonary function with the concentration of particles smaller than 10μm (PM 10 ) were found. These associations were not explained by exposure to acid aerosol, because concentration levels of acid aerosol were low during both the winter and the summer periods. For the general population samples of children, respiratory symptom prevalence was not associated with air pollution levels. For a panel of children with chronic respiratory symptoms, prevalence of wheeze and bronchodilator use was associated with the PM 10 concentration. For all study populations differences in pulmonary function response between individual children were found. However, determined characteristics of the children (age, gender, presence of chronic respiratory symptoms) did not explain the magnitude of the response to air pollution.The findings of the present study in combination with other recent studies support a revision of present guidelines for ozone and particulate matter.

Tijdens het voeren met een voerdoseerwagen komt er stof vrij. Met behulp van een stofzuiger op de voerdoseerwagen die het stof bij het afstortpunt wegzuigt, kan het stofgehalte in de stallucht tijdens het voeren gereduceerd worden.