More Americans now have access to top-performing, surgical-grade COVID-19 masks.

Major retailers like Kroger and Walmart either have or will soon have free N95 masks. They'll also be available at food banks and community health centers. Supplies are limited to three per person.

Scientists who study N95 masks say they can be worn until they're damaged or very dirty.

"Please do not put them in the oven or the microwave, don't spray them with any disinfectants," said Dr. Nikki Vars McCullough, a scientist with 3M. "It's best that you store your N95 respirator in a clean, dry place, like a paper grocery bag."

Vars McCullough says the N95 masks are designed to fit adults, so it's better to find a different option for children that comfortably covers their nose and mouth.

The material used in N95 masks is better at filtering out particles than the common blue and white surgical masks.

"N95 respirators are really sophisticated health and safety devices designed to help protect you. They have great filter media, and they're designed to seal to your face," Vars McCullough said. "That's why N95s really provide the highest level of protection of the face coverings that we have available now."

Vars McCullough says for those who don't have access to an N95 mask, a surgical mask is better than nothing.