• environmental health
• health inequalities
• epidemiology
• morbidity
• mortality

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 quickly, research has shown that exposure to the natural environment is associated with multiple beneficial outcomes, including lower mortality, higher birth weight, reduced risk of CVD and improved mental health.3 It is also associated with reduced risk of: allergies, type II diabetes, stroke and cognitive decline, although results have not always been consistent.3 We have recently shown, using linked data on nearly 50 000 infants followed for 18 years, that those growing up close to more green space were less likely to develop asthma.4 Using a similar approach, we have shown reduced risks of attention deficit hyperactivity disorder5 and childhood leukaemia.6

The idea that the natural …