Today we published a paper which builds on our ideas about equigenic environments – places that can reduce health inequalities – and continues the investigation of associations between nature and health. This new study builds on a paper CRESH’s Rich Mitchell published a long time ago (2008) with Dr Frank Popham, suggesting that populations which have more green space in their neighbourhood tend also to have a smaller health gap between richer and poorer residents. Other people have found something similar (see this for example, or this). The idea that ‘equigenic’ environments might be able to disrupt the usual conversion of inequalities in wealth to inequalities in health has gained attention, partly because it seems so difficult to do anything about the health gap that almost inevitably follows a wealth gap, and partly because politicians and society seem unwilling to tackle the wealth gap itself.
Actually though, the previous studies (including ours) which suggest that contact with nature might constrain or reduce health inequalities have three important weaknesses that I want to focus on here.
First, the existing studies did not compare green space with other features of the neighbourhood. That’s a problem because it is likely that neighbourhoods with better access to green space are also better in other ways; perhaps they also have better services or shops, for example. It might be those things which reduce the health gap between richer and poorer people, rather than the green space. Second, the existing studies were all about one country only. That makes it hard to generalise their findings to other countries because attitudes towards, and use of, green spaces might vary between countries &/or cultures. Third, the existing studies were focused on death or self-reported health. Yet, experimental studies from Japan and Scandinavia suggest that the biggest effects of green space might be on mental health and wellbeing. So, it is possible that the impacts of green space on health and health inequalities might actually be much bigger than we thought.
The study we published today in American Journal of Preventive Medicine tried to address these problems. It was based on data from 34 European nations collected within the 2012 European Quality of Life Survey (EQLS). The paper was focused on mental wellbeing, and compared several different neighbourhood characteristics in the search for an equigenic effect. We asked whether each neighbourhood characteristic was linked to a smaller difference in mental wellbeing between people with good financial circumstances and people with bad financial circumstances.
We measured mental wellbeing using the WHO-5 scale, which stems from asking people how they have felt over the two weeks prior to interview for the EQLS. Our measure of financial circumstances was people’s reported ability to make ends meet. EQLS asked people about their access to five different neighbourhood characteristics or services: recreational / green areas, postal services, banking services, public transport and cultural services (including cinema, theatre or a cultural centre). Respondents were also able to report that they did not use a service and this was important in helping us to interpret the results. The great thing about these data is that they allow us to look at each service, taking into account all the others.
Our analyses also took account of respondents’ age, sex, any illnesses which limited daily activities, education level, employment and reported problems in the neighbourhood with noise, air quality, crime, violence, vandalism, litter and traffic congestion.
What did we find? Only one neighbourhood service seemed to have a link with inequalities in mental wellbeing: green / recreational services. The graph below shows mean mental wellbeing score (a higher number is better mental wellbeing), by reported financial strain, for each level of reported access to green / recreational areas. The gradient in mental health (i.e. the difference in health between those with better and worse financial circumstances) gets shallower as reported access to green / recreational areas improves. In fact, inequality in mental wellbeing among those with the best access to recreational / green areas was about 40% less than those with the worst access. Full results and details of the models used, including formal tests for interaction, are available in the published paper.
How does this reduction in inequality occur, and is it real? We suspect the results reflect that the beneficial effects of using recreational / green space are felt more strongly by people in difficult financial circumstances, rather than reflecting differences in frequency or type of use of these areas. Psychology studies have shown the power of green areas to restore those who are stressed or fatigued (see this one, for example), and those under the most financial strain might well be the most stressed and fatigued. However, such experiments haven’t really looked at whether the effects vary by someone’s financial or economic circumstances, so this is just a working hypothesis at the moment.
Our new study is far from perfect and we discuss its weaknesses in the published paper. Perhaps the most important weakness is that the study was cross-sectional; the data are a snap shot in time. This means we could not prove that access to recreational / green areas caused the narrower inequalities.
Whilst all public health professionals should campaign to reduce the gap in wealth between richer and poorer people, we think it’s also important to consider additional ways in which the health gap between richer and poorer people might be reduced. The study published today suggest good access to recreational / green areas might help. Next, we need to look at this with study designs that are able prove whether or not this is a real, causal relationship.