'Wet-bulb' temperatures: What are they and why can they be so deadly?

With a heat dome over the U.S. and above-average temperatures expected in Canada this summer, there can be questions about how hot is too hot for the human body. When the temperature hits that mark and you stay in the heat for six hours or more you could face serious health impacts, but as Global’s Sean Previl reports, there are things you can do to stay safe.