would not otherwise be recognized or addressed. There are often not clear lines of authority between the team conducting the HIA and the decision-maker. The health effects that are included, the data sources and methods that are used, and the recommendations that are made are therefore determined by the HIA practitioners rather than according to a legal or regulatory standard (Wernham 2011). Thus, the assessment phase is separated from the management phase, as recommended elsewhere (NRC 1983). The fact, however, that the team conducting the HIA is aware of the decision context allows the assessment to be decision-relevant.
Scholars point to a remarkable consistency in the basic elements that are generally included in descriptions of HIA (Mindell et al. 2008). In practice, however, there is some inconsistency in how HIAs are conducted—for example, how stakeholders are engaged and how data are collected and analyzed—and in the structure and content of the final work products of an HIA. The diversity of practice owes partly to the fact that HIAs are undertaken for a wide array of policy-making that spans many sectors, levels of government, types of proposal (policies, plans, programs, and projects), and degrees of complexity. The variability in the practice has evolved in the absence of widely accepted practice standards or formal regulatory or procedural requirements for HIA outside NEPA and related state laws (see Appendix A). However, it appears to be increasingly accepted that HIA is carried out to inform the decision rather than to evaluate the impacts after the decision is made, and there is general agreement on the procedural steps of HIA (Harris-Roxas and Harris 2011).
HIA practice is often defined in terms of several categories. According to effort, complexity, and duration, HIAs are often described as rapid, intermediate, or comprehensive. Rapid HIAs may be completed in a short time (weeks to months), are often focused on smaller and less complex proposals, and generally involve primarily literature review and descriptive or qualitative analysis. The phrase desktop HIA has also been used to refer to a rapid HIA that entails little or no public engagement. Another variation, rapid-appraisal HIA, has been described and in some texts includes explicit public engagement through an initial half-day workshop for stakeholders (Parry and Stevens 2001; Mindell et al. 2003; ICMM 2010). Intermediate HIAs require more time and resources and involve more complex pathways, more stakeholder engagement, and a more detailed analysis but include little collection of new data. Comprehensive HIAs are most commonly differentiated from rapid and intermediate HIAs by the scope of potential impacts and the need for collection of new primary data. They can take longer than a year to complete.
HIAs are also differentiated according to whether they are integrated into an environmental impact assessment or done independently. Another categorization is based on the breadth of the HIA and distinguishes HIAs that have a tight