We'd had the same guideline level since 1988. The original guideline was set based on available research on miners' exposure. It was only in the early 2000s that there was new pooled research that distinctly demonstrated that there was a risk at lower levels in a residential environment, and that research led to Health Canada and our federal-provincial-territorial committee reviewing the guideline and lowering the reference level to 200. We knew at the time that was a significant decrease, and if we were going to decrease the guideline to that extent, we wanted to have a full program to support it to make sure that we educated Canadians about what the guideline meant, and the actions that they could take to reduce their risk.
