The Centers for Disease Control and Prevention is now recommending wearing double masks for the first time after it says research shows it can reduce the spread of COVID-19 by more than 90%.

For months, medical experts have been saying when it comes to COVID-19 masks save lives. But, new aggressive strains of the coronavirus have the CDC urging a new strategy. The agency now says two masks are better than one.

Rochelle Walensky, the CDC director, says, "In the breathing experiment, having both the source and the receiver wear masks modified to fit better, reduce the receiver's exposure by more than 95 percent compared to no mask at all."

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Why do some doctors believe so strongly in double masking? Bear in mind how the coronavirus spreads--through droplets. We expel these droplets each time we exhale. It's easy to visualize on a cold day.

The best way to stop the droplets is by wearing the gold standard of masks--the N or KN-95. Each blocks more than 95% of microscopic particles. The FDA says they typically have five layers. Two layers of polypropylene filter out large particles, another two layers remove medium sized ones and a filter gets the fine particles. Surgical masks have three of those five layers. There are no fabric layers, but the theory is by wearing a cloth mask over the top you can basically add them.

Another problem with surgical masks is they don't fit snugly against your face. There are gaps where air leaks in and out with each breath. Adding a cloth mask on top not only provides two extra layers, but it can also close some of those gaps leading to much better protection.

So medical experts say double masking is worth the inconvenience, but they admit getting people to do it may be a tough sell.

Folks have some trouble getting access to one mask, so to ask them to wear two masks may be a bit of a burden.