Health Impact Assessment (HIA)

The HIA procedure


2. Identifying what to do and how to do it

Scoping sets the boundaries for, and considers how the HIA appraisal stage should be undert aken. An example is the HIA scoping study of contract farming in Thailand. The study was designed to scope a potential HIA with a particular focus on stakeholder participation, and provide a HIA capacity building experience for local workers.

Thailand began by setting up a steering group to oversee and manage the HIA, and identify the necessary stakeholders/decision makers who needed to be involved (Ministry of Agriculture staff, staff from the private contract companies, and contract farmers). The geographical boundaries and relevant population groups were chosen (two sub-districts in Khon Kaen province in North-Eastern Thailand). Interviews were carried out with the stakeholders to determine the extent to which they could be involved in the HIA appraisal stage, to help determine what type of information was required (for example qualitative interviews, plus quantitative data), and to identify potential health impacts that would need investigating. For example, health impacts identified included physical fitness, neurological illness, visual acuity, malaise, fatigue, abortion, mental health issues, social health issues and spiritual health, to name a few.

Because the above study was a scoping study only, and it was unsure whether a full HIA would actually occur, some typical scoping issues were purposefully not considered. These were:

  • Who will do the HIA and who will be in charge
  • Are there any specialists or practitioners who could be involved?
  • What monitoring and evaluation of the HIA will occur.
  • When does the HIA have to be done by, to influence key decision makers (often influencing the choice of whether a rapid or comprehensive HIA is undertaken).
  • Setting and agreeing the aims and objectives of the HIA

Also, terms of reference for the HIA are often drawn up at this stage to clarify exactly what is expected from whom.

Rapid HIA

Refers to the appraisal stage which is carried out quickly (often only in days/weeks) with a limited amount of resource. However the preparation required for stakeholder consultation, searching and compiling evidence and writing the recommendations should not be underestimated.

Comprehensive HIA

An extensive appraisal stage, where new information is generated, significant literature reviews undertaken and comprehensive involvement of stakeholders often occurs. May take months or longer.


Kessomboon, P. 2002. HIA of agricultural policy on contract farming in Thailand. Proceedings of the International Association of Impact Assessment. 2002, The Hague.