A mask expert who's also a parent shares what masks he buys for his son to reduce his risk of COVID-19

• Aaron Collins goes by the "Mask Nerd" now that his unofficial job is reviewing face masks in his bathroom.
• Collins, an aerosol expert, compiled a list of the best child-sized masks to protect against COVID-19.

Thousands of parents turn to Aaron Collins for advice on which face masks they should buy for their kids.

Since January 2021, Collins has put his background in aerosol science to use in testing how well various face masks block coronavirus-sized particles. He started trying out adult masks, then child-sized options for his five-year-old son.

A mechanical engineer by trade, Collins has access to scientific equipment that can turn his home bathroom into a makeshift laboratory. He started posting his findings on YouTube and soon began answering questions posed by his more than 21,000 subscribers.

The question that parents ask the most often is which mask his young son — dubbed "Mask Nerd Jr." — wears to school, Collin said in an August video about masks for kids.

He added that he can't guarantee that a mask he reviews will properly fit a viewer's child, since his own test pool is quite limited. In general, he recommends buying a variety of masks in similar sizes to compare and find the best fit for your child.

Collins' son wears a Korean face mask that may fit 4-to-9-year-olds

The mini mask nerd loves his KF94, a South Korean standard that comes in sizes to fit all ages. Collins said his son's favorite is the Blue (industry brand) "tiger mask," a plain white boat-style mask that has a tiger superhero on the packaging.

The boat or duckbill style, which has a flat panel in front instead of a seam down the middle, can fit the majority of faces if sized properly. Collins' son wears a size small, which is advertised to fit kids between the ages of four and nine.

He also likes a similar style "ducky" mask by Bluna, another Korean brand. Both masks are currently sold out at Collins' recommended retailers, which include Korean beauty stores that get their products imported.

A couple of those stores — Be Healthy USA for the tiger mask and KollecteUSA for the ducky — have notices on their websites saying they'll resume shipping the sold-out masks January 17.

More high-quality mask options for kids of all ages can be found on a spreadsheet where Collins compiled the best ones he tested, along with links for where to buy them.

The US lacks a mask standard that applies to children

Without a general population mask standard in the US, finding kid-sized masks is hard.

The numbers and letters we've come to associate with masks — N95, KN95, KF94, and so on — reflect a test standard put in place by the manufacturing country. But in the US, that standard only applies to adults.

​​The National Institute for Occupational Safety and Health (NIOSH) has been responsible for workplace safety in the US for more than 50 years. Part of that job includes approving N95 respirators, which were originally designed for industrial use.

Until COVID, there wasn't much demand for kid-sized respirators in the US. Small children shouldn't be working, especially not in settings where PPE is needed, so NIOSH has no stake in the issue, Collins said.

But that leaves a big gap in the US mask supply, which is why experts like Collins often look abroad for tiny, top-notch masks.