intake of fruit, vegetables, vitamin a, vitamin c and fiber among sixth graders. harvesting fruits and vegetables initiates the enzymatic process of nutrient degradation which is especially detrimental to water soluble vitamins such as ascorbic acid and thiamin. the process of blanching produce in order to freeze or can reduce nutrient content slightly, but not nearly as much as the amount of time spent in storage. harvesting produce from one's own community garden cuts back on storage times significantly. urban agriculture also provides quality nutrition for low-income households. studies show that every $1 invested in a community garden yields $6 worth of vegetables if labor is not considered a factor in investment. many urban gardens reduce the strain on food banks and other emergency food providers by donating shares of their harvest and providing fresh produce in areas that otherwise might be food deserts. the supplemental nutrition program women, infants and children (wic) as well as the supplemental nutrition assistance program (snap) have partnered with several urban gardens nationwide to improve the accessibility to produce in exchange for a few hours of volunteer gardening work. urban farming has been shown to increase health outcomes. gardeners consume twice as much fruit and vegetables than non-gardeners. levels of physical activity are also positively associated with urban farming. these results are seen indirectly and can be supported by the social involvement in an individual's community as a member of the community farm. this social involvement helped raise the aesthetic appeal of the neighborhood, boosting the motivation or efficacy of the community as a whole. this increased efficacy was shown to increase neighborhood attachment. therefore, the positive health outcomes of urban farming can be explained in part by interpersonal and social factors that boost health. focusing on improving the aesthetics and community relationships and not only on the plant yield, is the best way to maximize the positive effect of urban farms on a neighborhood. economy of scale using high-density urban farming with vertical farms or stacked greenhouses, many environmental benefits can be achieved on a citywide scale that would be impossible otherwise. these systems do not only provide food, but also produce potable water from waste water, and can recycle organic waste back to energy and nutrients. at the same time, they can reduce food-related transportation to a minimum while providing fresh food for large communities in almost any climate. health inequalities and food justice a 2009 report by the usda determined that "evidence is both abundant and robust enough for us to conclude that americans living in low-income and minority areas tend to have poor access to healthy food", and that the "structural inequalities" in these neighborhoods "contribute to inequalities in diet and diet-related outcomes". these diet-related outcomes, including obesity and diabetes, have become epidemic in low-income urban environments in the united states. although the definition and methods for determining "food deserts" have varied, studies indicate that, at least in the united states, there are racial disparities in the food environment. thus using the definition of environment as the place where people live, work, play and pray, food disparities become an issue of environmental justice. this is especially true in american inner-cities where a history of racist practices have contributed to the development of food deserts in the low-income, minority areas of the urban core. the issue of inequality is so integral to the issues of food access and health that the growing food & justice for all initiative was founded with the mission of "dismantling racism" as an integral part of creating food security. not only can urban agriculture provide healthy, fresh food options, but also can contribute to a sense of community, aesthetic improvement, crime reduction, minority empowerment and autonomy, and even preserve culture through the use of farming methods and heirloom seeds preserved from areas of origin. environmental justice urban agriculture may advance environmental justice and food justice for communities living in food deserts. first, urban agriculture may reduce racial and class disparities in access to healthy food. when urban agriculture leads to locally grown fresh produce sold at affordable prices in food deserts, access to healthy food is not just available for those who live in wealthy areas, thereby leading to greater equity in rich and poor neighborhoods. improved access to food through urban agriculture can also help alleviate psychosocial stresses in poor communities. community members engaged in urban agriculture improve local knowledge about healthy ways to fulfill dietary needs. urban agriculture can also better the mental health of community members. buying and selling quality products to local producers and consumers allows community members to support one another, which may reduce stress. thus, urban agriculture can help improve conditions in poor communities, where residents experience higher levels of stress due to a perceived lack of control over the quality of their lives. urban agriculture may improve the livability and built environment in communities that lack supermarkets and other infrastructure due to the presence of high unemployment caused by deindustrialization. urban farmers who follow sustainable agricultural methods can not only help to build local food system infrastructure, but can also contribute to improving local air, and water and soil quality. urban farming serves as one type of green space in urban areas, it has a positive impact on the air quality in the surrounding area. a case study conducted on a rooftop farm shows the pm2.5 concentration in the urban farming area is 7-33% lower than the surrounding parts without green spaces in a city. when agricultural products are produced locally within the community, they do not need to be transported, which reduces co2 emission rates and other pollutants that contribute to high rates of asthma in lower socioeconomic areas. sustainable urban agriculture can also promote worker protection and consumer rights. for example, communities in new york city, illinois, and richmond, virginia, have demonstrated improvements to their local environments through urban agricultural practices. however, urban agriculture can also present urban growers with health risks if the soil used for urban farming is contaminated. lead contamination is particularly common, with hazardous levels of lead found in soil in many united states cities. high lead levels in soil originate from sources including flaking lead paint which was widely used before being banned in the 1970s, vehicle exhaust, and atmospheric deposition. without proper education on the risks of urban farming and safe practices, urban consumers of urban agricultural produce may face additional health-related issues. implementation a small urban farm in amsterdam rooftop urban farming at the food roof farm in downtown st. louis, missouri creating a community-based infrastructure for urban agriculture means establishing local systems to grow and process food and transfer it from farmer to consumer. to facilitate food production, cities have established community-based farming projects. some projects have collectively tended community farms on common land, much like that of the eighteenth-century boston common. one such community farm is the collingwood children's farm in melbourne, australia. other community garden projects use the allotment garden model, in which gardeners care for individual plots in a larger gardening area, often sharing a tool shed and other amenities. seattle's p-patch gardens use this model, as did the south central farm in los angeles and the food roof farm in st. louis. independent urban gardeners also grow food in individual yards and on roofs. garden sharing projects seek to pair producers with the land, typically, residential yard space. roof gardens allow for urban dwellers to maintain green spaces in the city without having to set aside a tract of undeveloped land. rooftop farms allow otherwise unused industrial roofspace to be used productively, creating work and profit. projects around the world seek to enable cities to become 'continuous productive landscapes' by cultivating vacant urban land and temporary or permanent kitchen gardens. urban agriculture project in the la romita section of colonia roma, mexico city tomato plants growing in a pot farming alongside a small house in new jersey in fifteen garbage cans filled with soil grew over 700 tomatoes during the summer of 2013. food processing on a community level has been accommodated by centralizing resources in community tool sheds and processing facilities for farmers to share. the garden resource program collaborative based in detroit has cluster tool banks. different areas of the city have tool banks where resources like tools, compost, mulch, tomato stakes, seeds, and education can be shared and distributed with the gardeners in that cluster. detroit's garden resource program collaborative also strengthens their gardening community by providing access to their member's transplants; education on gardening, policy, and food issues; and by building connectivity between gardeners through workgroups, potlucks, tours, field trips, and cluster workdays. in brazil, "cities without hunger" has generated a public policy for the reconstruction of abandoned areas with food production and has improved the green areas of the community. farmers' markets, such as the farmers' market in los angeles, provide a common land where farmers can sell their product to consumers. large cities tend to open their farmer's markets on the weekends and one day in the middle of the week. for example, the farmers' market of boulevard richard-lenoir in paris, france, is open on sundays and thursdays. however, to create a consumer dependency on urban agriculture and to introduce local food production as a sustainable career for farmers, markets would have to be open regularly. for example, the los angeles farmers' market is open seven days a week and has linked several local grocers together to provide different food products. the market's central location in downtown los angeles provides the perfect interaction for a diverse group of sellers to access their consumers. argentina the city of rosario (population: 1.3 million) has incorporated agriculture fully into its land-use planning and urban development strategy. its land use plan 2007-2017 makes specific provision for the agricultural use of public land. under its metropolitan strategic plan 2008-2018, rosario is building a "green circuit", passing through and around the city, consisting of family and community gardens, large-scale, commercial vegetable gardens and orchards, multifunctional garden parks, and "productive barrios", where agriculture is integrated into programs for the construction of public housing and the upgrading of slums. in 2014, the green circuit consisted of more than 30 ha of land used to grow vegetables, fruit, and medicinal and aromatic plants. the city has five garden parks – large, landscaped green areas covering a total of 72 ha of land, which is used for agriculture and for cultural, sports and educational activities. australia various studies argue that the increased usage of urban agricultural practices in australian cities could profoundly mitigate the consequences of climate change and promote food security. in one 2020 study, the authors demonstrated that using 25% of vacant land and yard space in sydney for urban agriculture practices could boost food supply by up to 15%. in light of these benefits, urban agriculture is growing more common in australia, particularly in the form of urban farms and roadside gardens. in some cities, local councils have even encouraged urban agriculture by providing residents with guidelines to support roadside gardens. in others, however, planning policies and regulations have impeded access to sufficient and suitable land for urban agriculture. regardless, insufficient suitable land has been a major obstacle to the spread of the practice in australian cities. in queensland many people have started a trend of urban farming and utilizing aquaponics and self-watering containers. british columbia a canadian urban farmer in british columbia has published details on a crop value rating (cvr) system that urban farmers can use to determine which crops to grow, based on each crop's contribution to supporting the farm economically. this entails forgoing some crops in favor of others, but he points out that urban farmers can develop business networking with rural farmers to bring some of those other crops to the urban point of sale. for example, the urban farmer may not be able to economically justify growing sweet corn (based on long days to maturity and low yield density per linear foot of row), but a networking arrangement is mutually beneficial, as it lets a rural sweet corn grower gain an additional point of sale at retail price while also letting the urban farmer fill the gap in his product line offering. several community projects in victoria, british