But how much, how long and what kind.

Here's what the scientists at the University of Florida say to be most effective, a dime sized dollop of alcohol gel should be rubbed into the hands for 30 seconds.

If hands are dry after only 10 or 15 seconds, it's likely not enough sanitizer was used.

30 seconds is a long time to rub your hands dry, and I want to show you exactly how long 30 seconds is.

So we're going to put a clock on the screen to show you while I talk about alcohol content.

The packaging should tell you how much alcohol is in the gel, and the experts say the higher the better.

Though the sweet spot is between 60 and 95% alcohol, they warn that the higher concentrations are actually not as effective. 00:00:59.740 --> 00:01:4.850 That's because there needs to be a little bit of water in there to cause the reaction that kills bacteria. 00:01:5.120 --> 00:01:6.160 And here we are, right. 00:01:6.160 --> 00:01:9.150 At 30 seconds, my hands should finally be dry. 00:01:9.350 --> 00:01:10.550 It's along 30 seconds.