Monday, July 25, 2011

Urban agriculture - where's the evidence?

Creative Commons Image: City Farm in Chicago, US

One potential way to combat the obesity epidemic and environmental degradation all in the same go is urban agriculture. I’ve been thinking a lot about this lately, wondering if it is feasible in climates like New York City and Toronto, if it can actually generate enough food to continuously feed a city, and of course, also improve diet quality at a population-level.

Urban agriculture refers to agricultural practices (usually intensive) within and around cities that compete for resources such as land, water, energy, and labour – but produce food, plant and animal-based pharmaceuticals, fibre, and fuel that benefit the local population (crops and animal husbandry included).  This can occur at the micro and meso scales of cities – e.g. using vacant lots, backyards, street verges, green roofs and walls, balconies, community gardens, urban parks, and individual collective garden allotments. Larger scale practices can include commercial farms, nurseries, and greenhouses, which would likely operate in peri-urban areas and be private/corporate, for-profit entities.

There are a number of other potential benefits for UA, aside from food, food security, and pollution/land degradation that I hadn’t initially thought about. These include: 
  • Employment and income
  • Personal skill development
  • Social interaction/community or social capital-building
  • Increased well-being
  • Highest productive use of land (with respect to vacant lots)
  • Diversified industry base
  • Light, odour, and noise abatement/absorption 

I was surprised to read in a recent journal article that in developed countries like Australia, UA is responsible for 15% of state vegetable and fruit production. And that in Sydney, UA accounts for 1% of land area but contributes $1 billion in agriculture produce.  Those are interesting numbers, but I still feel skeptical; this is Australia after all, where temperatures rarely fall below freezing. And I imagine that most of this occurs at the macro, not the micro or meso scales.     

Most research on UA in terms of any type of outcome, not just health (e.g. environmental, social, and economic) has been in the form of case studies, with no real quantification of its benefits. It is difficult to build an argument for this practice with no hard evidence. At the same time, it has the potential to positively affect many different aspects of society, not just health. For this reason, I think UA is worthwhile.

I don’t, on the other hand, believe that farming at the micro and meso scales of cities (involving individuals and communities), especially in northern North America, can continuously feed local residents. Farming is time-intensive, and requires certain knowledge and skills. And to feed families year-round in North America, would require up-front investment for equipment like greenhouses. This is not compatible in a culture that breeds convenience and instant gratification, where for example, we don’t seem to have enough time to clean out reusable containers for our drinks, so instead buy crates of water bottled in plastic that can be thrown out or recycled.       

This may be different if UA at the micro/meso level is a social business, or a private/corporate entity. An example is the Science Barge in New York City, a 1300-square-foot greenhouse that floats on the Hudson River. It is a sustainable urban farm powered by solar, wind, and biofuel and irrigated by rainwater and purified river water. Fresh fruits and vegetables are grown using recirculating hydroponics and aquaponics. And surprisingly, despite floating on the river, is a prototype for a sustainable roof-top garden (more information on the Science Barge can be found here).  

Another example is Gotham Greens, a roof-top greenhouse in Brooklyn, NY that grows vegetables and herbs for local restaurants and retailers using sustainable methods. They expect to produce 80 tons of produce yearly, and employ residents in nearby communities.

Gotham Greens greenhouses

Macro-level UA in urban fringes using sustainable methods has potential, but right now is often more costly or harder to access than buying produce at supermarkets like Loblaws or Metro. Government policies (e.g. zoning) and community initiatives that support local farms will be needed to make buying local economically feasible and physically accessible to everyone. An example of this support is Equiterre, a Montreal-based organization that maintains a directory of Community Supported Agriculture (CSA) farms that must be local and organic, serving primarily low-income sharers (clients that share the risk of farming). The organization connects potential sharers with CSA farms, and coordinates drop-off points that increase accessibility for sharers, while at the same time minimizing transport time and cost to the farms. CSA produce prices are cheaper than what you would find in a supermarket, and the average farm is family run and has between 30-80 sharers.       

In terms of improving diet quality, many questions about UA in developed countries remain – can individuals and communities do it to feed themselves year-round? My guess is no. Is it economically feasible for social businesses, and for-profit private/corporate entities in urban and peri-urban areas? If so, will it be socially equitable and improve diet quality at the population-level? Given UA’s potential to benefit many different areas of society, I believe it is a worthwhile pursuit irrespective of scientific evidence. That being said, if further investment (time, money, policies, etc,) is to be made in UA, rigourous trans-disciplinary studies need to be conducted to quantify its benefits.       
Pearson, L., Pearson, L., & Pearson, C. (2010). Sustainable urban agriculture: stocktake and opportunities International Journal of Agricultural Sustainability, 8 (1), 7-19 DOI: 10.3763/ijas.2009.0468

Tuesday, July 12, 2011

Some musings on sustainability and obesity: focusing on BOTH physical activity & diet needed

There is no disputing that diet and physical inactivity are contributors to the obesity epidemic. A recent debate involving Drs Yoni Freedhoff and Bob Ross showed that both are important (I don’t think there was consensus in the audience as to who won). What I want to highlight in this post is that, from a sustainability perspective (see my previous post for a definition), it is a moot point to argue over the relative importance of each.

Our food system has changed dramatically over the last few decades. We can get tasty, energy dense, often nutrient-poor foods anywhere, for very little money. And we’re constantly bombarded with advertisements to buy and eat these foods. What’s more is that we have almost completely engineered physical activity out of our daily life. For instance, most jobs nowadays require sitting for 8 hours (I am sitting as I write this), escalators and elevators do the climbing for us and are easily accessible, and we live far from where we work, play, or go to school so often must rely on the car, which involves more sitting.

I think there is a consensus developing among obesity researchers and health professionals that obesity (or diabetes or other related diseases) is not entirely the fault of the individual. In my opinion, unhealthy behaviours are a natural response to our “obesogenic” environment, which increase a person’s risk of developing obesity. So then why do we expect that prevention or treatment efforts targeted at the individual will be effective and maintained over the long-term? To fix our deranged food system and culture of sitting requires interventions at higher levels of social organization, including changes stemming from the local community, municipal, provincial, and national governments, as well as the global community.

In the last 10 years there has been a boom the number of scientific studies examining how our environments, beyond the household, are associated with obesity. The majority of these studies have been observational, with a cross-sectional design, and have looked at things like how street infrastructure, fast food restaurant density, and socioeconomic-level of residential neighbourhoods relate to obesity among adults.  Children have been less studied in this regard, as well as other types of environmental exposures, such as social interactions, and other types of areas, such as those around workplaces and schools (since these are likely not in one's residential neighbourhood).  Perhaps because of the complexity involved, even fewer studies have examined how specific policies and programs may influence physical activity, diet, and obesity at higher levels of social organization (you can find an example here).    

Certainly more studies are needed given the weaknesses in the current literature, as well as the dearth of information in some areas. But I would like to put forward another argument.  Increasing the “walkability” and “liveability” of our shared spaces - *may* decrease obesity but will likely help to decrease green house gas emissions. Making it easier for us to get and cook wholesome foods (namely fruits and veggies) that are free of pesticides, antibiotics, and other chemicals, and harder to get meat, as well as processed foods *could* decrease obesity, but could also help to reduce land degradation, pollution of our water sources, and climate change. All of these things are good for our health in ways other than on our waistline.       

My argument is that if there is a focus on sustainability, which these changes imply, population and environmental health should follow.  We need to focus on BOTH the diet and physical activity side in order to not only combat obesity, but a myriad of environmental problems and related health ailments like diabetes and asthma.  These changes are complex, don’t happen overnight, and may bring with them a whole set of new problems (the potential problem of denser living leading to a decrease in indoor air quality immediately comes to mind as an example). 

Nonetheless, I think we need to move towards rigorously implementing and evaluating interventions that increase sustainability – looking to see if they a) improve the environment, b) reduce obesity, or improve lifestyle behaviours, and c) that they do not negatively impact health in other ways (a post for another day).
Feng J, Glass TA, Curriero FC, Stewart WF, & Schwartz BS (2010). The built environment and obesity: a systematic review of the epidemiologic evidence. Health & place, 16 (2), 175-90 PMID: 19880341