As a tool for deliberately planning for and optimizing the ways in which we design our environments, Health Impact Assessment (HIA) holds promise for achieving environmental justice and health equity. This case study describes the application of HIA to updating a rural county's General Plan. Humboldt County, California is currently considering three development plans to accommodate future population growth, and the described HIA process successfully identified and analyzed potential health outcomes associated with each. Although the General Plan Update process is not yet complete as of this writing, the HIA has already accomplished one of its initial goals, which was to build awareness of health impacts related to planning decisions among county agencies, project decision-makers, participating community members, and the general public. Another noteworthy outcome of this process, which is intended to aid in planning future equitable and just communities, was the development of the ''Rural Healthy Development Measurement Tool,'' a tool for considering health in rural development decisions.

Air pollution contributes to asthma, allergies, lung function impairment, cardiovascular disease, and premature mortality. Transit-oriented development, roadway expansion, new residential and commercial development, and pollution mitigation projects impact local and regional air quality. This article discusses the use of Health Impact Assessment (HIA) by community advocates, public health and city planning departments, and regulatory agencies to ensure health impacts are considered in decision-making processes that affect air quality. HIAs encourage collaboration among diverse stakeholders, including communities facing health inequities. HIAs also use data and analysis to predict health outcomes of proposed planning and policy decisions. This article describes the collaborations, empirical assessment tools, communication and advocacy strategies, findings, recommendations, and outcomes of the following HIAs: a transit-oriented station area plan in Pittsburg, CA, grade separations funded through a policy to levy a fee on all port containers passing through major ports in California, and a freeway expansion in Los Angeles, CA.