By this point, it’s pretty clear that one of the best things we can do to protect ourselves and others from the coronavirus is wearing face masks whenever we’re out in public. But it’s important to remember that this disease is still new, and scientists are still learning about it. And now, the CDC has updated its face mask recommendations, warning people that masks that have built in valves or vents aren’t actually effective in helping slow the spread of the virus. One extremely popular model of mask that has a built-in valve is made by 3M. Its high-tech appearance...