Facilities that use designated substances in their process must undertake an assessment to ensure workers are not adversely exposed. This requires a review of a facilitys MSDS library to identify if a designated substance is used. A site visit is usually required to gather information about the process and potential routes of exposure. In some cases air monitoring to determine a workers exposure is necessary. A final report is produced detailing the process, results from air monitoring, and if there is need for a control program.

In Ontario there are eleven designated substances: