Early in the pandemic, Aaron Collins stared in frustration at a pile of face masks on his counter. N95 masks, the gold standard of personal protection, were nearly impossible to buy. The rest—cloth masks, surgical masks, Korean KF94 masks—were a big unknown. The government also offered no guidance early on to help users select the right one.

His wife suggested, “Why don’t you test them?”

Why not? Collins (B.M.E. ’07, M.S.M.E. ’10) has degrees in mechanical engineering from the U of M, with a background in aerosol science. He pulled out testing equipment from his basement, set up a lab in his bathroom, and began testing masks. He recorded the procedures and posted videos to YouTube for his friends and other engineering nerds. If a thousand people watched, he thought, “I’d be floored.” Soon thousands, and then hundreds of thousands of other confused people tuned in and began to clamor for more information.

Thus began the unlikely odyssey of the Mask Nerd (on Twitter: @masknerd). Collins became a national authority on the efficacy of masks. He popped up in stories for The New York Times, Washington Post, and Scientific American. He appeared on CBS News and CNN with Sanjay Gupta. His testing has been noted by nationally known experts in aerosol science.

“I didn’t see anyone else doing it, so I was going to be stupid and do it myself,” says Collins. “Almost everyone goes into engineering to solve problems and help people. This really embodied everything I loved about engineering.”

Doing this voluntarily with no pay, Collins also has a day job at Seagate, a digital storage manufacturer.

Collins learned the cloth and surgical masks people use are leaky and only modestly effective. High-filtration masks now available filter out well over 95 percent of aerosols (such as viruses) in the air. Masks also help protect others from infection.

Collins also found that good masks withstand considerable abuse. One line in his mask-test spreadsheet summarizes the test of a mask with “4 months in car + Random Use.” Despite the wear, the mask blocked nearly 95 percent of aerosols. Says Collins, “Those kinds of questions are the things that people are really interested in.”

At this stage of the pandemic, people should be wearing“high-filtration” masks that block at least 94 percent of aerosols, he adds. He says the best earloop masks are Korean-made KF94s and Chinese KN95s (though fakes still infiltrate the market). U.S.–made N95s are a step up, with headbands that pull the mask tighter for a better seal. One of Collins’s favorites is the 3M-made 9205+. It fits a wide range of faces, is easy to breathe through, and removes, according to his test, more than 99 percent of aerosols—all for roughly $2.

Collins has been disappointed by the Centers for Disease Control response to Covid and mask-wearing. “They really failed at communicating how this disease spreads, the mechanisms, and acknowledging the precautionary measures that engineers use on a daily basis,” he says.

Only early this year—two years into the epidemic and nearly two months after the appearance of omicron—did the CDC begin urging Americans to upgrade to high-filtration masks. By comparison, he notes that South Korea supplied high-quality KF94 masks to every citizen by spring 2020. “It is frustrating to see how much better we could have done,” says Collins.

Collins says he owes a huge debt to the U of M Mechanical Engineering Department scientists and engineers that have “a positive impact far beyond what they know. That’s why we need universities. They’re powerful tools for good.”

Greg Breining is a Twin Cities writer.