If you’re a stressed-out office worker, one of the simplest things you can do for yourself is to buy some flowers. A study conducted by Chiba University in Japan found that employees who had a vase of pink roses on their desk became physiologically calmer, even after just four minutes. The smell of roses is so soothing that it has been shown in experiments to make people better drivers: slower, more relaxed and less likely to crash. Another study, which used an EEG to measure brain activity while participants were looking at flowers, found that yellow ones were best for boosting productivity and creative thinking.
Kathy Willis is professor of biodiversity at Oxford, and her new book on the emerging science of how nature can improve our health is filled with practical tips, showing how increasing our exposure to plants by even small amounts can make a significant difference. Willis became interested in these surprising effects while working as director of science at Kew Gardens; she came across a 1984 paper published in the journal Science that found patients who had undergone gallbladder operations recovered faster when they could see trees, rather than a wall, from their hospital window. In a similar vein, research has shown that when school or university students can see greenery through their classroom windows they perform better and feel less stressed.
Why would simply looking at plants have such a profound impact? In the 90s, the behavioural scientist Roger Ulrich and his colleagues proposed so-called stress reduction theory, arguing that we are biologically predisposed to pay attention to natural scenes, and that when we do so it induces a more “positively toned emotional state”. Experiments have since demonstrated that looking at vegetation triggers physiological changes that make us more resilient to stress. Some scientists believe this is part of our evolutionary inheritance, harking back to the savannah-like landscapes in which our African ancestors once lived.
Apart from vision, smell is one of the most direct mechanisms by which the natural world can alter our inner state. Volatile organic molecules known as pinenes are emitted by many trees, but especially conifers, and are responsible for the refreshing fragrance of forests – and of Christmas trees. Just 90 seconds spent smelling air infused with pinenes reduces your heart rate. And the scent of cypress and juniper trees has not only been shown to make people feel more relaxed, but also to boost natural killer cells, which are responsible for helping our bodies ward off viruses and cancer – suggesting that we may have been massively underestimating the potential medicinal benefits of a woodland walk.
Willis has lighted on an intriguing, exciting subject, and it’s a shame that she deploys so few of popular science writers’ usual tricks for bringing it to life: there are no interviews with scientists or visits to pioneering projects to rewild urban spaces, no real stories. In a chapter on the health benefits of gardening she includes a long, unremarkable quote from “the relative of a good friend”, when I am sure that she could have visited any allotment in the UK and returned with compelling tales of lives transformed through growing vegetables – to say nothing of the charities using gardening to support ex-prisoners or people with poor mental health as they rebuild their lives. As a result, Good Nature comes across as a rather dry overview of the latest research, with frequent digressions into, say, the science of petal colours, and Willis misses opportunities to hammer home the political and social implications of her work.
After all, she notes that antidepressant prescriptions are lowest in the London boroughs with the greatest density of trees, even when accounting for other factors such as the local unemployment rate. Similarly, a study looking at neighbourhoods in Milton Keynes, Luton and Bedford found that rates of anxiety and depression were lower when at least 20-35% of the land around houses comprised trees or shrubs. It estimated that more planting could lead to local healthcare savings of £0.5bn-£2.6bn a year. Despite this, the public provision of green spaces is declining. Willis also writes that almost a third of new and remodelled buildings are “sick”, designed in ways that increase people’s risk of non-communicable diseases such as cancer, diabetes and cardiovascular disorders. Reading her book, I realised that unequal access to nature is a far bigger social justice issue than I had understood, but Willis doesn’t really go there.
Instead, she is keener to emphasise the steps we can take as individuals to harness the health-boosting benefits of nature, arguing that we needn’t wait for urban planners and politicians to create more green spaces for us. Good Nature is therefore filled with suggestions for measures almost anyone can take, from introducing a daily 20-minute nature walk to gardening without gloves and putting plants outside your front door (front gardens have a greater impact on our mental health than back gardens).
If Willis had made more of the politics of greening our urban spaces and the buildings that are literally killing us, Good Nature would have been a bigger and more ambitious book. But it still inspired me to change my life in various small ways. I vowed to buy more houseplants (and try harder not to kill them), and let my children spend more time playing in the mud. And I bought myself some flowers.
• Good Nature: The New Science of How Nature Improves Our Health by Kathy Willis is published by Bloomsbury (£20). To support the Guardian and the Observer buy a copy at guardianbookshop.com. Delivery charges may apply.
