Our findings also suggest that increase in contribution

Our findings also suggest that increase in contribution of income to inequalities could be related to changes in the distribution of income within Canada and the United States. Recent work by Bernabé and Marcenes (2011) suggest the degree of state income inequality may be attributed to inequalities in tooth loss in the United States, which may imply if income were more equally distributed across a population, inequalities in oral health would be reduced (Health Canada, 2010). The Organisation for Economic Co-operation and Development (OECD) reported that income inequality in the United States is considerably higher than other developed countries and has increased substantially since the 1980s (Bernabe & Marcenes, 2011); income inequality has also increased in Canada since 1976 (Forster & Levy, 2014). Bhandari et al. (2015) found that income inequality, total health expenditure, public expenditure on health, health system responsiveness, and type of dental health system explained the association between income inequality and use of dental services (Bernabe & Marcenes, 2011). Therefore, changes and differences in dental and social safety nets, and the quality of dental coverage between and within countries may explain differential access and affordability issues to dental care experienced between income groups (Stamm, 1986). All of which reinforces the notion that inequalities in oral health may be explained by factors beyond the individual-level (Bhandari et al., 2015). Although such changes could explain the increased contribution of income to inequalities over time, the mechanisms as to how they relate to health inequalities are not fully understood nor cannot be confirmed from our analysis (Rajotte, 2013).
Conclusion
Acknowledgements
Introduction Exposure to greenspace and natural environments can provide mental and emotional health benefits (Bowler, Buyung-Ali, Knight & Pullin, 2010; Lee & Maheswaran, 2010; Francis, Wood, Knuiman & Giles-Corti, 2012). Urban parks, in particular, provide opportunities for physical activity, play, social interaction, and relaxation for different segments of the purchase dpn (Lee and Maheswaran, 2010; Francis et al., 2012; Kazmierczak, 2013; Peters, Elands & Buijs, 2010). As a public good, parks are accessible to large proportions of urban populations, and can support a diverse range of activities. Thus, urban parks are important settings for improving population health (Bedimo-Rung, Mowen & Cohen, 2005). To improve park planning and design, more evidence on how park environments influence usage patterns is needed. Evidence from natural experiments investigating the relations between the built environment and physical activity is beginning to emerge (McCormack & Shiell, 2012; Koohsari et al., 2015) yet few examine changes in park use and activity following park modifications. For instance, the installation of new play and outdoor fitness equipment in parks, in addition to ground surfacing and landscaping improvements, led to an increase in visitors and the amount of energy expended by park visitors (Cohen et al., 2015). Elsewhere, the installation of outdoor fitness equipment in parks led to increased energy expenditure among visitors, mainly due to increases in moderate and vigorous-intensity activity resulting from the use of the installed equipment and changes in the demographic profile of visitors following the modifications (Cohen, Marsh, Williamson, Golinelli & McKenzie, 2012). Likewise, improvement to ground surfaces, new fencing, lighting, landscaping, and addition of benches to two parks in a US low-income neighbourhood resulted in increases in park and playfield use, changes in the demographic profile of visitors, but also increases in the proportion of sedentary activity (Tester & Baker, 2009). Indeed, not all studies report improvements in park physical activity or visits following park modifications. For example, Cohen et al. (2009) found no improvements in observed or self-reported physical activity following modifications to several parks, such as the development or refurbishment of gymnasia, landscaping, picnic areas, paths, and ground surfaces surrounding play equipment. Concurrent changes in park programming (organized sports, operating hours etc.) alongside park modifications however, may contribute to changes in park use and activity (Tester & Baker, 2009; Cohen et al., 2009).