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This thesis explores the potential role of greenspace to promote physical activity in young adolescents in Scotland through an examination of physical activity behaviour associated with greenspace use and adolescents motivations to use greenspace, and experiences, attitudes and perceptions of greenspace. This is in light of political interest in promoting physical activity in all populations, especially in young people, as one way to help prevent obesity and promote health and well-being, and recognition that a link between greenspace provision and greenspace has been suggested by research, however, the evidence base is currently limited, particularly within Scotland. Research into greenspace links to physical activity are usually framed within an overarching socio-ecological perspective, however, additional theoretical perspectives are discussed which can add to understanding of adolescents’ use of greenspace. An argument is made for the use of Gibson’s Theory of Affordances and this is further developed to make the links between greenspace design, provision and use. The research included two studies. Study one involved the design, testing and placement of greenspace use questions into a survey of a nationally representative sample of 13 and 15 year-olds across Scotland (n=4697). This was done in collaboration with the Scotland team for the Health Behaviour in School-aged Children (HBSC) survey. The second study used a mixed methods design which employed GPS (global positioning system), accelerometry and GIS (geographical information system), referred to in this research as the GAG method, as an objective measure of physical activity location, timing and duration for a sample of n=35 13 and 15 year-olds. This is a relatively new method used in environment and physical activity research and the present study makes a contribution to understanding this method in practice. The GAG study also included semi-structured interviews with participants at the end of the period of monitoring physical activity. The two studies combined demonstrated a positive association between use of greenspace and higher quantity of and intensity of physical activity. Logistic regression on the survey data revealed that an adolescent who used greenspace more than three times per week was 42% more likely to achieve 60 minutes of moderate physical activity daily. The GAG study demonstrated that, when in greenspace, a lower proportion of time was spent being sedentary compared to when not in greenspace (48.6% vs. 81.7%). In interviews, the adolescents described a wide variety of physical activities taking place in greenspace, many incidental to being in greenspace as opposed to planned beforehand, although this was also encountered. Four types of greenspace user were identified and helped highlight how social motivations to use greenspace were paramount suggesting that the impact of greenspace on physical activity is both a result of motivation to be active, but also a benefit of going to greenspace for social reasons. This bi-directional relationship complicates endeavours to demonstrate cause and effect and suggests the requirement for more research to understand the interaction between psycho-social and environmental factors. Greenspace use appeared to be relatively high. The HBSC survey found that a large majority of young adolescents in Scotland (71%) reported using greenspace at least once per week in the summer months, and may well be one of the most frequent users groups. However, scope remains to further increase use aimed at increasing physical activity and it is argued that more flexibility exists for this possibility than within other domains for physical activity, such as school PE classes. The interviews revealed that motivations and influences on use of greenspace were found to closely reflect the a priori model (based on previous mainly public space research) with clear evidence of interplay between factors influencing intention and opportunity. Developmental attributes of the adolescent stage were indicated to be strongly influential in motivating greenspace use, however, the relative impact of the range of factors was uncertain with decisions to use greenspace complex and dynamic. Despite this complexity, improvements in the physical condition of greenspace, safety and greenspace quality are likely to be universally welcomed. From a theoretical perspective, the findings supported the existence of design, normative and individual affordances which have relevance for how greenspace and the facilities within them are designed and used and how exclusionary practices can arise. Political endorsement of the importance of greenspace to health and well-being is evident and this research supports continued protection, investment and improvement, particularly in greenspace quality. There is, however, a need to further develop policy to incorporate consideration of the role of youth and community services and park management aimed at facilitating positive use of and experiences in parks and other greenspace for all users.

A time series study was conducted to investigate the association between variations in daily levels of air pollution and health effects in the city of sao Paulo, Brazil. This study was prompted by positive associations reported in other time series studies, principally in North AmeriE:a and Europe, and preliminary results from some limited analyses reported for sao Paulo. Its aims were to examine specific causes of mortality and hospital admissions, to identify more vulnerable subgroups defined in terms of age, to assess the role of socio-economic conditions in modifying the association and to detail the impact of other potential risk factors, especially meteorological. Daily measurements of air pollutants (PM10, S02, N02, 0 3 and CO) for 12 monitoring stations across the city and several meteorological variables, along with daily counts of mortality for all ages during 3 years and hospitalisations for children during 23 months were available. The time series models used Poisson regression analysis and were adjusted for effects of trend, cyclical patterns (including season), weekday, holidays, meteorological factors, and autocorrelation. Increases in PM10 and S02 were associated with a 3-4% increase in daily deaths for all causes in the elderly (results are presented for an increase from the 10th to the 90th centile of pollution measurements). Cardiovascular deaths were additionally associated with CO (4% increase). Respiratory deaths in the elderly showed higher increases (6%) associated with PM10• No significant effects for children's mortality were observed. Nevertheless, respiratory or pneumonia hospital admissions for children showed significant increases associated with 0 3 (5-8%), N02 (9%), and to a lesser extent with PM10 (9%). There was a significant trend of increasing risk of death according to age with effects only evident for older subjects. However, this age effect was more evident for all cause mortality. There was a weak suggestion of larger effects on mortality for areas economically more affluent. Some indication was found of a harvesting effect occurring in the mortality and hospital admission series in sao Paulo. Results are broadly consistent with those previously reported but somewhat smaller in magnitude. In contrast with an earlier preliminary analysis in Sao Paulo, there were no effects on mortality for children. However, new analyses for hospital admissions indicated that children are at an increased risk of non-fatal illness in relation to air pollution.

An opportunistic study was carried out in central Mexico, where one of the world's largest wastewater reuse schemes for agricultural production is located. This scheme provided a unique opportunity to assess the health impact of exposure to wastewater of different qualities on intestinal parasitic infections and diarrhoeal diseases. The central objective of the study was to evaluate the effect of hydraulic retention on reducing the health risks associated with wastewater use. Exposure groups were defined according to eligibility procedures and to the quality of irrigation water. Microbiological quality was measured using nematode eggs and faecal coliforms as indicators. The exposure groups involved households: a) exposed to untreated wastewater; b) exposed to wastewater retained in a single reservoir; c) exposed to wastewater which had passed through two reservoirs in series, and been retained for some time in both; and d) nonwastewater-exposed households (controls). The study outcomes included risk of Ascaris lumbricoides, Entamoeba histolytica and Giardia lamblia infections, as well as the risk of diarrhoeal diseases. The study design was based on two cross-sectional surveys (rainy and dry seasons), and the analyses focused on both comparison of risks between the different exposure groups as well as the identification of at-risk groups. The two surveys involved different intermediate groups - (b) and (c) above - and the main purpose was to assess the effects of single versus double hydraulic retention. They are distinguished mainly for this purpose, rather than the evaluation of possible seasonal fluctuations of the study outcomes. Other variables (i.e. socioeconomic, hygiene and sanitation) were analysed as confounders using a multivariate model. In young children the prevalence rates of A. lumbricoides infection were considerably higher in the raw wastewater group (13.7%), and lower prevalences were observed with decreasing exposure (11.8% in the single reservoir group, 3.3% in the double reservoirs group, and 0.6 - 2.5% in the control group). A high prevalence rate of G.lamblia was observed in children (17 - 20.5%), but no association with untreated wastewater was found. The prevalence rates of E. histolytica infection in children from the various exposure groups ranged between 4.8 - 7.0%, but were considerably higher in older individuals: 15.7 and 16.5% in the two surveys among the raw wastewater group, compared with 13.2% and 14.7% respectively in the controls. In addition, a high prevalence of diarrhoeal diseases (two-weeks recall period) was found in the rainy season, particularly in young children from the raw wastewater exposure group, and lower prevalences were observed with decreasing exposure (29.0% in the raw wastewater group, 26.8% in the two reservoirs group, and 23.0 % in the control group, respectively). The overall prevalences of Cryptosporidium parvum and Trichuris trichiura infections were unexpectedly low (below 1% and 4%, respectively), and excluded from further consideration. The intensity of A. lumbricoides infection was evaluated in a parallel study, and is not reported here. The main findings of the present study can be summarised as follows: - Cropland irrigation with raw wastewater was strongly associated with A. lumbricoides infection in farmworkers and their families, with a risk of diarrhoeal diseases, and with a small but significant risk of E. histolytica infection in individuals aged over 5 years. - The differences observed in the prevalences of A. lumbricoides infection and diarrhoeal diseases were similar in both seasons, but the prevalences in the control group were lower in the dry season; thus, the relative effect of wastewater use was greater in the dry season. - Retention of wastewater in two reservoirs in series (2-6 months) reduced substantially the risk of A. lumbricoides infection, and to a lesser extent the risk of E. histolytica infection, and possibly the risk of diarrhoeal diseases in young children. - Retention of wastewater in a single reservoir (1 - 7 months) did not reduce the risk of A. lumbricoides or E. histolytica infection, but may reduce the ri sk of diarrhoeal diseases in children by 20%. - No association between exposure to raw wastewater and infection with G. lamblia was detected in this research. - Parasitic intestinal infections and diarrhoeal diseases showed significant associations with variables describing personal and domestic hygiene, basic sanitation and socioeconomic characteristics. These results are discussed in relation to local regulations and health protection measures, as well as in light of the WHO 1989 revised guidelines for restricted crop irrigation.

Alcoholism is a serious illness that is marked by uncontrollable drinking and physical dependence to alcohol. Long-term alcoholism has been linked to many health concerns such as cirrhosis of the liver and cardiovascular disease. Alcohol is one of the most commonly used drugs among adolescent populations. Given that adolescence is a unique developmental stage during which alcohol has long-term effects on future drug-taking behavior; it is essential to understand how early exposure to alcohol during adolescence may affect the abuse liability of the drug later in life. Indeed, most alcohol users start during adolescence suggesting that exposure to alcohol during adolescence increases the risk of alcohol abuse in adulthood. Our studies focus on identifying behavioral mechanisms involved in alcohol dependence during adolescence by using well-established mouse models of alcohol drinking. Our hypothesis is that exposure to alcohol during early adolescence will increase alcohol intake later in adulthood. We investigated the impact of alcohol drinking in male and female early adolescent C57BL/6J mice using the Drinking In the Dark (DID) model. Our results showed that exposure to alcohol during early adolescence enhanced ethanol intake later in adulthood in the DID and the 2-bottle choice drinking paradigms. In contrast, adult exposure of alcohol did not enhance later alcohol intake. Our data illustrates that enhanced alcohol intake are affected by the duration, age of exposure, and mouse genotype. In addition, we conducted behavioral studies to elucidate in part the mechanisms underlining the relationship between adolescent ethanol exposures and enhance alcohol intake in adult mice. We hypothesized that these changes in alcohol intake are due to an alteration between ethanol aversive and rewarding properties. Our results showed that ethanol exposure during adolescence induces a less aversive state (less withdrawal intensity in the FST test) later in adulthood. In contrast, our results showed that ethanol exposure in adolescence enhanced the rewarding properties of ethanol in the CPP test and alcohol intoxication (as measured by the LORR test). Overall, our results suggested that this increase in the alcohol intake was correlated with an increase in alcohol rewarding properties and a reduction of alcohol aversive effects. Further research will be required in order to more fully examine the mechanisms of action for the observed changes in alcohol intake.

Benzene is a leukaemogenic and mutagenic agent, which may pose a risk to the general public even at low levels of exposure. Since petrol fuel contains a high concentration (1-5%) of benzene, there is the potential for exposure to man during car journeys. The main aim of this study was to develop and validate a sensitive method to detect urinary t,t-muconic acid (uMA) following low level environmental exposures to benzene. Subjects potentially exposed to benzene were divided into petrol (n= 9) and diesel groups (n= 7). The control group (n=14) consisted of individuals who were not exposed to benzene inside the car. The uMA method developed during this study involved butanol extraction instead of the traditional solid phase extraction followed by DV (259nm) detection. The method was reasonably precise (CV=1.5%) with >80% recovery from urIne. Air samples were collected on charcoal tubes and analysed for benzene, toluene, ethylbenzene, and xylenes by GCMS following extraction with purified carbon disulphide. The benzene concentration of ambient air samples taken from inside the cabins of petrol fuelled cars (7.5 ppb) was about triple that found from diesel-fuelled cars (2.6 ppb)(P=O.Ol). The uMA of volunteers exposed to petrol increased (p<0.01) post-sample in compared to pre-exposure level (0.66mgMA/gCr and 0.38mgMA/gCr, respectively). There was no increase in uMA for volunteers exposed to diesel. The uMA level of samples collected from individuals 2h-7h after exposure to petrol showed a significant association with the air benzene (p=0.012) and toluene (p=0.042) concentrations taken inside the car cabins. Half of the 24h-profiles of individuals exposed to petrol had at least one urine with 1 mgMA/gCr or higher, while all of the profiles of controls were below 1 mgMA/gCr. The technique developed in this study for the determination uMA showed promise as a tool for monitoring levels of benzene arising from low-level environmental exposures to petrol.