The age-adjusted incidence of many non-communicable diseases (NCDs: allergies, asthma, autoimmune disease, some cancers, diabetes, neurodegenerative diseases, cardiovascular disease (CVD) and so on) is rising.1 They are leading causes of hospitalisation and death and many have reached epidemic proportions, with marginalised populations most affected. Causes remain unclear and prevention options are thus often scant or not optimally effective. However, as increases have occurred in recent decades, environmental and lifestyle factors are probably central. Some risk factors are well studied (tobacco, air pollution, diet, physical activity) and clear associations with several NCDs are now established. Nonetheless, they do not account for all cases and often do not explain geographical and temporal trends, suggesting roles for other exposures.
One underexplored influence on NCDs is exposure to the natural environment. Since the pioneering work of Ulrich,2 who found that surgical patients with a view overlooking a natural scene recovered more…