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The built environment is associated with various environmental exposures such as air pollution, noise, and fast-food outlets. In this thesis, we use environmental data at fine resolution and we integrate time-activity information in exposure assessment methodologies to study the relations between environmental factors and health, and to investigate the distribution of exposures among groups with different socio-economic status (SES). To test the exposure methodologies and examine the associations between environmental exposures and health we applying them in existing cohorts. The thesis is divided into three parts. In the first part, the associations between air pollution and health in children are examined by using exposure assessment methodologies which incorporate time-activity patterns. We showed that air pollution exposures are consistently associated with decreased carotid artery distensibility in children 5 years old. Furthermore, by comparing the associations between air pollution and lung function, by using four exposure assessment methodologies, we concluded that the annual average exposure to air pollution for 8-year-old children in the Netherlands is sufficiently captured by the residential exposures. In the second part of the thesis we studied the associations between fast-food environment and cardio-metabolic diseases. Individual level analysis showed that the presence of fast-food outlets near the residential address showed significant associations with the presence of both cardiovascular diseases (CVD) and diabetes. The strength of the associations varied among the network buffer-sizes used in the exposure assessment. The smaller buffer (500m) showed the strongest associations between fast-food outlet environment and CVD in the urban environment. The presence indicator (exposed or not to fast-food outlets) in urban areas showed the most consistent associations among the buffer sizes. In the third part, disparities in environmental exposures and exposure response among social groups in the Netherlands were investigated. We showed that unfavourable environmental exposures were higher for neighbourhoods in the highest and lowest quartiles of SES score and individual income compared to the two mid-quartiles. Neighbourhoods with a higher proportion of impoverished residents are characterised by higher levels of air pollution, noise and green space.

Though numerous epidemiological studies have observed consistent associations between exposure to ambient air pollution and adverse health effects, the underlying mechanisms of these effects have not yet been fully established. Ambient particulate matter (PM) is currently regulated on a mass basis, but not every component in the PM mixture is equally important. As PM toxicity is most likely to reflect exposure to the sum of multiple toxic components, oxidative potential (OP), which measures the inherent capacity of PM to oxidize target molecules, has been proposed as an additional exposure metric alongside PM mass concentrations. Whilst OP is considered a promising metric, actual application in epidemiological studies is limited. This thesis evaluates the value of oxidative potential (OP) of particulate matter (PM) as a health-related exposure metric for air quality assessment, with these specific aims: 1) 1) To compare OP assays and evaluate the impact of extraction solvent and filter type on these OP assays 2) 2) To assess the spatial and temporal variation of OP in ambient air 3) 3) To evaluate the relationships of ambient OP with indoor and personal exposure 4) 4) To evaluate the relationship of long-term exposure to OP of PM with respiratory health in children. Our findings suggest that the choice of filter type has a stronger influence on measured OP than extraction solvent; however, the relative OP reactivity is not influenced by filter type or extraction solvent. OP has high spatial and temporal variations, with road traffic being a major source of OP. Measurements of OP at a central monitoring site were found to represent wider surroundings. Furthermore, central site OP measurements were a reasonable surrogate for personal exposure in assessing short-term health effects of OP. Land use regression model could well predict the spatial variation of OP. These models were used to investigate the relationship between the OP and the respiratory health effects of children. The OP of particulate matter was significantly correlated with respiratory symptoms and reduced lung function in children.

Within the framework of the ESCAPE project (European Study of Cohorts for Air Pollution Effects), we aimed to characterize and explain spatial contrasts in ambient air pollution within and between European study areas. Following a standard protocol, project partners selected “street” and “background” measurement sites in 36 study areas, and measured using identical equipment. NO2 and NOX measurements were available from 40 different sites in each area (80 in The Netherlands/Belgium and Catalunya). PM2.5 (particles

The first part of this thesis is about the VE3SPA project. Land use regression (LUR) models are often used to predict the outdoor air pollution at the home address of study participants, to study long-term effects of air pollution. While several studies have documented that PM2.5 mass measured at a central site correlates well in time with personal exposure, little is known about how well spatial variation of home outdoor concentration predictions represent personal exposure. For this project, outdoor and indoor concentrations were measured at 15 participants in Utrecht (the Netherlands), Helsinki (Finland) and Barcelona (Spain). Simultaneously, the personal exposure was measured for these 45 participants using pump units in small backpacks. Measurements were conducted for 6 times 96 hours (Monday- Friday) in three different seasons (winter, summer and spring/autumn). The aim was to assess the association between LUR predicted home outdoor concentrations and measured personal exposure of particulate matter with a diameter of

People spend a substantial proportion of their time in traffic. In Europe, the average daily time in traffic is one to one and a half hour. Because of high in-traffic exposures and because most of the journeys are made during rush hours, the one to one and a half hour in traffic contributes disproportionately to total daily exposure to traffic related air pollution. So far a limited number of studies compared particulate matter exposures of different groups of commuters. There is limited evidence of health effects of the typically short but high exposures in traffic. Long-term exposure to traffic-related air pollution as well as short-term (daily) changes in traffic-related pollutants are related to cardiopulmonary mortality and morbidity. The TRAVEL study (Transport Related Air pollution, Variance in commuting, Exposure and Lung function) examined air pollution exposures of different groups of commuters and acute health effects of typical short exposures in traffic. In-traffic exposures of particle number (PN), PM2.5, PM10 and soot were measured in the city of Arnhem during morning rush hour. Exposures were measured in diesel and in electric trolleybuses, in diesel and in petrol cars, and along a high- and low-traffic bicycle route. Exposure levels in diesel buses were 20 to 40% higher than in electric trolley buses, though not for PM10, that mainly derives from other sources than diesel exhaust. Exposure levels between new diesel and new petrol cars did not differ. Cyclists air pollution exposure was 40 and 35% lower on the low-traffic route compared to the high-traffic route for ultrafine particles and soot, respectively, not for PM10 or PM2.5. PM10 and soot exposures of cyclists were lowest, whereas PN exposure in electric buses was lowest. Because of their increased minute ventilation, the inhaled doses of all studied air pollutants were highest for cyclists. Inhaled doses of electric bus passengers were lowest for all studied air pollutants except for PM10. Lung function, airway resistance, exhaled NO (nitric oxide, marker for airway inflammation) were measured and blood samples were taken before and after exposure in the 34 healthy, adult volunteers. Associations were found between in-traffic exposure to PN and soot and changes in lung function, airway resistance and exhaled NO. PN, PM10 and soot were associated with peak expiratory flow directly following but not six hours after exposure. PN and soot were associated with increased exhaled NO after car and bus trips but not after bicycle trips. PN inhaled dose was associated with an increase in airway resistance directly following exposure, but not six hours later. There were no associations between air pollutant exposures and blood inflammation markers. There were inconsistent associations between air pollution exposure and blood cell counts and coagulation markers. The study showed that air pollution exposure is affected by commuting mode, fuel type and route. Two hour exposure in traffic is associated with respiratory health effects, but no associations were found between exposure and blood markers of inflammation and coagulation and blood cell counts within hours following exposure.