Public spaces could promote health equity by providing a place for people to engage in physical activity. Whereas most studies show a positive association between public spaces and physical activity, there are still mixed results, especially in low- and middle-income countries. The objectives of this mixed-methods study were: (i) to assess the quantitative association between access to public spaces and physical activity; (ii) to assess the modification of the association by public spaces quality, area-level walkability, and social stratifiers; (iii) to explain the quantitative results using qualitative data. Quantitative data were obtained with a household survey in two arid-climate Mexican cities in 2017-2018. physical activity was measured with the Global Physical Activity Questionnaire. Access to public spaces was measured in buffers centered on survey blocks, walkability with area-level indicators, and public spaces quality with the Physical Activity Resources Assessment. Qualitative data were obtained with semi-structured interviews and neighborhood observation. No quantitative association between access to public spaces and physical activity was found, as well as no interactions between access to public spaces and other variables. Walkability was positively associated with physical activity. Qualitative analysis showed that local public spaces were rarely used by adults because they were perceived as small, unequipped, unattractive, and unsafe. The results shed light on the relationship between public spaces and physical activity, highlighting the improvements in design and upkeep of public spaces that are necessary to achieve their potential health benefit.

Con una población fundamentalmente urbana, México enfrenta grandes retos en cuanto a la planeación y distribución equitativa de las áreas verdes urbanas, desde una perspectiva de los servicios ecosistémicos que éstas proveen. El objetivo de este trabajo es profundizar en el conocimiento y las causas que originan la inequidad en la distribución y provisión de las áreas verdes urbanas y los servicios ecosistémicos que proporcionan. Para ello, se realizó una búsqueda sistemática de literatura especializada, comprendiendo desde 1990 a la fecha. De 34 publicaciones seleccionadas, se codificaron y analizaron parámetros de provisión, accesibilidad, calidad, percepción y su relación con factores socioeconómicos, los problemas existentes y sus causas (método PRISMA). Los resultados muestran que existe inequidad en la provisión, acceso y calidad de las áreas verdes, que afecta principalmente a personas de escasos recursos y a ciertos grupos de población. Las causas de ello tienen un origen legal, administrativo y de incumplimiento de la ley, combinado con factores históricos y de formas de crecimiento urbano. El análisis revela que el uso de conceptos y metodologías diferentes producen variaciones en los resultados. Se demuestra la influencia que el concepto de área verde utilizado tiene en la determinación de los tipos de servicios ecosistémicos que éstas prestan, así como en el análisis de su distribución equitativa.

In rapidly growing urban areas, such as Tijuana, Mexico, the presence of urban green spaces (UGSs) can help stem soil erosion, improve infiltration, slow runoff, decrease flooding, reduce air pollution, and mitigate climate change. In many water-scarce parts of the world, where centralized wastewater treatment is not accessible or practical, decentralized wastewater treatment systems (DEWATSs) have the potential to supply the water needed for irrigating UGSs. Here, we first review UGS systems supported by DEWATSs and the water quality guidelines and challenges associated with implementing DEWATSs for urban greening in different countries, including Mexico. We also critically examine the linkages between the lack of UGSs in Tijuana, Mexico, extensive soil erosion, and failing sanitation infrastructure that has led to the infamously poor water quality in the Tijuana River. Tijuana’s Ecoparque Wastewater Treatment Facility, a low-energy, aerobic DEWATS, which collects, treats, and discharges residential sewage for localized landscape irrigation, demonstrates how DEWATSs can meet the water demands for urban greening in rapidly urbanizing cities. The aerobic decentralized treatment using a gravity-fed trickling biofilter resulted in a >85% removal of chemical oxygen demand and dissolved organic carbon. Prior to treatment facility upgrades, there was a ~2 log reduction in total coliform and Escherichia coli and a <20% decrease in ammonia from the influent to final effluent. After the addition of a maturation pond in 2020, the effluent met Mexico standards for irrigation reuse, with a ~4 log reduction in fecal coliforms from the influent to final effluent. Case study results demonstrated the potential for decentralized wastewater treatment to meet effluent standards for landscape irrigation, provide water for urban greening, and prevent pollution in the Tijuana River and other urban waterways.