With the flu season well-underway, many questions are coming in about the difference between an outbreak and a pandemic.

But what factors characterize an influenza pandemic rather than a localized outbreak, and how does Health Canada monitors these changes?

In this week's Science Smart video column, the CBC's Johanna Wagstaffe tells us how a flu is tracked and when and how it's labelled as dangerous.

If you have a science question you'd like answered, send Johanna a tweet (@Jwagstaffe) or an email: johanna.wagstaffe@cbc.ca.