The international scheme recognises three levels of qualification
- Foundation level for those who have studied the basic principles of occupational hygiene, an Award of Successful Course Completion
- Intermediate level for those who have studied the technical knowledge and practical skills needed to undertake occupational hygiene in the workplace, the International Certificate in Occupational Hygiene (ICertOH)
- Advanced level for those who achieve the levels of knowledge and skill expected of a professional hygienist. This normally requires an academic qualification.
The two lower levels use a formative approach to learning which makes assessment an integral part of the learning process. At the Advanced level, assessment may be part of the academic process for a postgraduate degree or diploma. The scheme can thus serve the needs of students from early technician training through to professional development. It encourages a process of "spiral learning", where materials are studied to progressively higher levels. The scheme is already in use, with courses are held around the world by companies, universities and other training providers.