Mel Willis
Donald Bren School of Environmental Science and Management
University of California, Santa Barbara
March, 2003
For the last three decades, public concern about environmental pollution has become a significant factor in the U.S. political process. The growth of cities and the population exodus to suburbs have concentrated a significant portion of the U.S. population in urban communities in proximity to sources of environmental pollutants, potentially exposing segments of the population to industrial, municipal and transportation effluents and waste products. Although the problem of environmental pollution is complex with a myriad of interactions, it is ultimately related to land use.
Under the U.S. federal system of government, the power to regulate an activity by private persons (e.g., land use) in order to protect the health, safety, morals, and general welfare of the public is an expression of the police power, and resides with the state governments; local governments have no authority to regulate land use unless specifically delegated by the state (Buck 1996) . Most states, however, have delegated the authority to regulate land use to municipalities and county government, but there is significant variation between states on the limits of that authority (Babcock 1979) . According to the International City/County Management Association, “in general, local governments are responsible for protecting and ensuring the public’s health and safety, improving and sustaining a community’s quality of life, maintaining a healthy economy, balancing individual interests with the interests of the larger community, and providing an equal opportunity and open process for public participation” (International City/County Management Association 1997) .
The principal regulation of land use by local government is normally exercised through its general plan and zoning ordinance. A local government’s general plan and zoning ordinance are related, but not the same thing. The general plan is a long-range policy document that functions as a “blueprint” for the future development of the community (California. Governor's Office of Planning and Research 1990) . The general plan functions as the local government’s statement of policy about the types of development that will be allowed, the spatial relationship among those land uses, and the general pattern of future development. Zoning regulates development in the present by setting specific standards by ordinance for allowable uses, lot size, and buildable area (Fulton 1999) . The major characteristic of the practice of zoning is the division of a municipality into “zones or districts with uniform regulation throughout the district but with different regulations for each district” (American Law Institute 1976) .
Since publication by the National Research Council in 1983 of Risk Assessment in the Federal Government: Managing the Process (National Research Council 1983) , risk assessment and risk management have become increasingly integrated into a wide range of public policy decisions at the federal, state, and local government levels in the U.S. Although health risk assessment has become a common decision-making tool of local government, it is primarily used for evaluation of the short-range effects of individual development projects or property transfers rather than for long-range land use policy decisions.
Human health risk assessment and management is the process of protecting the public from exposure to toxic chemicals. Risk assessment methodology generally focuses on the impact of existing or past development; however, land use planning is future-oriented and uses broad categories of land use, which introduces a degree of uncertainty about the specific type and scale of land use on a given parcel of land. If environmental problems are ultimately related to land use and local government agencies exercise the principal authority for controlling the use of land in urban communities, how effective is the local government land use planning process at protecting the residential population from exposure to toxic environmental pollutants? A review of the literature and available case studies found little evidence that community health risk assessment and management is a significant component of the local government land use planning process, and no evidence of any attempt to quantify the health risk implications of long-range land use planning decisions.
A recently released study found that the spatial pattern of carcinogenic risk from hazardous air pollutants in the Los Angeles basin ranged from 1,120 per million people to 1,740 per million (South Coast Air Quality Management District 2000) . This suggests that land use planning in the Los Angeles basin has affected the spatial pattern of exposure, but has not been effective overall at protecting residents from significant carcinogenic risk (based on the EPA criterion for significant cancer burden of one per million).
The most comprehensive survey of the industrial risk assessment process in local government was a 1997 report prepared by the International City/County Management Association (ICMA) for the National Governors’ Association, under a grant funded by the U.S. EPA’s Office of Research and Development (International City/County Management Association 1997) . Using information obtained through telephone and written questionnaires from local government officials involved in risk assessment and management, the ICMA concluded, “the definition and process of risk management still remains a broad, scientific, unclear, and politically charged concept for many local governments.” The ICMA found that risk assessment and risk management of industrial facilities was primarily performed by state agencies and that the role and degree of involvement by local government in this process varied significantly, but was mainly indirect participation. The 33 case studies documented by the ICMA report all involved activities by local governments to assess the human or ecological risk from past industrial operations—a reactive process; no examples were provided of local government taking proactive or preventative actions to protect the public from future industrial development risk, such as through long-range land use policy—the community general plan. The 1997 ICMA concluded their report with the following finding and recommendation:
In a period of increasing state and local flexibility, diminishing resources, and a growing demand for enhanced community involvement, local officials need to have better access to human health and environmental risk and decision-making tools, to help their communities better understand their risks, to set priorities based on their risks, and to manage risks in the most effective and inclusive way possible.
My research thesis is that although long-range land use policy decisions by local governments significantly influence the spatial pattern of population exposure to hazardous air pollutants (HAPs), land use planning by local governments has not effectively considered the community health risk implications of these policy decisions. This can be explained by the traditional reliance of the planning process on broad categories of land use and the lack of a suitable framework for assessing the community health risk implications of alternative land use patterns.
The goal of my research was an approach for integrating community health risk characterization into the land use planning process. The objective was a spatial decision support system linked to risk exposure simulation and land use optimization models. The focus of my research was community health risk exposure from direct HAP releases by the manufacturing sector, and indirect release of HAPs from mobile sources generated by land uses within a community and the surrounding region.