Human settlements worldwide have experienced environmental problems as a result of population growth, an increase in productive activities and low financial capacity of municipalities to provide adequate infrastructure and public services. At the local level, problems of water, soil and air pollution, as well as, land use changes have arisen due to the expansion of urban agglomerations. Regionally, there have been negative impacts on watersheds, ecosystems and biodiversity. Globally, the world is experiencing climate change, the reduction of the ozone layer and the increase of natural disasters. The situation has posed a challenge in terms of urban and regional planning, especially for metropolitan areas and medium-sized cities. The purpose of this study is to present an alternative to integrate environmental sustainability into metropolitan planning in Mexico, specifically applied to the Metropolitan Area of Mexicali, Baja California. Therefore the Environmental Sustainability Agenda has focused on three objectives: first, identifying the weaknesses of the existing environmental and human settlements legal framework; second, developing an environmental assessment and; third, designing policies, strategies and indicators to implement institutional monitoring of environmental programmes. The results were obtained by conducting surveys, regional community workshops, and reviewing previous research. Lastly, this study concludes with six sectoral programs: water, air, solid wastes, green areas, soils and physical pollution and six transversal Sustainable Development and Planning VI 267programs that have effects on environmental education, health, climate change, environmental management and the legal framework.

Urban development planning in Mexico begins with the publication of the General Law on Human Settlements in 1976, which sets up several planning instruments to regulate land use and urban development at state, municipal and urban level. Urban planning in the late seventies was characterized by being made by the state, with a rational approach, enforced from a top-down perspective, supported by planning guides made by professional planners and public consultation at the end of plan making. Current urban planning has been modifying its methods to a strategic and communicative model, a bottom-up perspective. The state has been playing a regulatory function and the participation of stakeholders has become a central issue on urban development planning and management. Therefore, this study has two main purposes: firstly, to analyse the evolution of urban planning in more than four decades and; secondly, to present Mexicali city as a good practice case study of the application of the bottom-up planning model. This project shows the changes that urban development has undertaken throughout a strategic planning view, oriented to long term perspective, organized and undertaken by society with collaborative work coming from different sectors: government, private and nongovernmental organizations. The methodology was based on the Logical Framework Approach, working along nine months with thematic groups. The results were integrated in a project portfolio, to be implemented in the short, middle and long term. Lastly, findings show successes in urban development planning and obstacles that society has faced in order to implement development projects within a political municipal agenda.

There is a worldwide increase in the number of people living in cities. As a consequence, this brings a number of social, economic and environmental problems relating to a decline of the environment and the quality of life. Air quality stands out among the problems of medium and large cities, mainly due to the increase of industrial activity, urban mobility, mobility from one city to another and of urbanization levels. That is why human settlements face important challenges in order to lower the levels of emission of pollutants into the atmosphere that are considered aggressive and hazardous for the built up environment, ecosystem and human health. In this context, the city of Mexicali stands out in the country for the problems relating to air quality it faces, mainly pollutants such as CO, PM10 and O 3. This report presents the results of research which has the purpose of designing a system of indicators for the study of air quality in the city of Mexicali, based on the pressure-state-response (PSR) model from OECD. This system is complemented with information of other urban variables, as well as population, traffic infrastructure, transportation, and land uses among others, trying to identify which strategies need to be applied in the city. Lastly, an urban assessment about pollution and strategies that can be applied in different fields involved in air quality is presented. Keywords: urban air quality, environmental management of air quality, atmospheric pollution, sustainable urban planning.www.witpress.com, ISSN 1743-3541 (on-line)

The regional-urban development planning is a relatively recent response to the changes in the economic processes of production and foreign trade which experienced profound changes over the past two decades. With these changes, globalization and national openness impacted the economic, social and territorial relations in the metropolitan area of Mexicali. This area experienced a central expansion increasing the mobility of vehicles. The importance of urban-regional network in its territory also augmented. These changes impacted the economic base, gradually reducing the importance of agriculture and industry while services, mobility and economic diversification in the territory of Mexicali increased. The desert environment, demographic concentration and mobility in a very small territory with a very dry and warm weather, have posed challenges for future sustainable development in its metropolitan territory. From the results and the experience of a collective planning process and of civic integration, key challenges were identified in the scenarios to promote appropriate and successful answers in the planning of sustainable development for an extreme territory and with economical competence.

A escala mundial, el problema de la contaminación del aire en los asentamientos humanos presenta una tendencia creciente, resultado del incremento en las demandas de energía y emisiones que tienen las actividades productivas y domésticas, producto de los procesos de urbanización e industrialización. Desde esta perspectiva, las ciudades no se encuentran planeadas para minimizar dichos impactos a partir de la estructura y el funcionamiento de las mismas. De ahí que el trabajo cumpla un doble propósito: por un lado, plantear la evaluación de la calidad del aire en la ciudad de Mexicali, a partir del análisis de los contaminantes: O3, CO, SO2, NO2 y PM10 y su relación con la estructura urbana; y por otro, mencionar y evaluar las estrategias instrumentadas para el abatimiento de la contaminación. Finalmente, se propone un esquema de planeación y gestión urbana que incorpora aspectos de calidad del aire.