Everyone knows that environment affects health, and in cities, air quality, sanitation and public hygiene all play into our likelihood of developing everything from asthma to heart disease. But researchers have found that, in Philadelphia at least, health can vary widely from neighbourhood to city neighbourhood. And it’s partly down to less obvious factors like how helpful the neighbours are and the quality of local facilities.

The researchers, at the city’s Drexel University,were particularly interested in diabetes (Philadelphia has the highest incidence across all US cities). They examined the connection between “physical and social environment” (PSE) factors – including the availability of healthy food on a hyper-local level, recreational facilities, poverty, the presence of an active and friendly community – and the incidence of diabetes. What they found is that PSE factors determine about 12 per cent of the risk of contracting the condition.

In other words, improve a neighbourhood enough, and you can cut its residents’ chance of diabetes by 12 per cent.

Consider these maps. Areas in red have at least double the prevalence of the areas in blue. What’s more, the most at-risk areas are roughly consistent across the two different time periods studied. In other words, not only does the age-adjusted prevalence of the illness varies wildly between the city’s different zipcodes; they are changing at different rates.

Of course, there are still other major factors at play: education and race also have an impact on individuals’ prevelance for the disease. But the results imply that neighbourhoods with different socioeconomic environments could create more than just educational or opportunity disparities: they could actually effect residents’ current and future health on a zipcode-by-zipcode level.

Ana E. Nunez, co-author of the paper, says that the study points to a new approach to city health:

Too often, we focus exclusively on the individual in solving the problem. Here we found that we also need to focus on the healthiness of the community if we want to improve overall health and ultimately decrease health care costs.

You can view a full write-up of the study on the Drexel website here.