It’s possible medical supplies will be in limited quantity as the number of COVID-19 cases continues to rise but Russell Medical invented a way to help extend the duration of its N95 mask supply with the help of ultraviolet (UV) rays.
Senior director of facilities services Mike McCaleb — with the help of his son Tucker McCaleb who is a chemical engineer and 2015 BRHS valedictorian — researched the physics to sterilize N95 masks. Maintenance manager Shannon Browning brought their scientific studies to life in the creation of an ultraviolet C (UVC)-lighted box.
“Shannon did a great job taking the concept we developed and turning it into a safe reality,” Mike McCaleb said. “UVC is the only UV ray that is germicidal.”
By figuring out the strength of UV lights surgical masks can handle without degradation allows them to be sterilized properly for additional use.
“The (Centers for Disease Control and Prevention) says UVC rays can eradicate 99.99% of the virus at 1 joule per centimeter squared,” McCaleb said. “This would mean 24 masks at 30 seconds per side but to be safe we were able to double up at 2 joules per centimeter squared for two minutes each side to make the masks sterile and maintain their integrity.”
This is a preemptive measure Russell Medical is taking in preparation of running low on its supply of masks, which are vital for employees dealing with COVID-19 positive patients, waste or rooms.
“It’s important for the community to know that we are being proactive and we’re prepared if this continues to drag on and supplies are at a minimum,” Russell Medical director of marketing Susan Foy said. “We’ll be ready.”
At the moment, Russell Medical is stocked and not in fear of running out any time soon but things could escalate.
“We’ve kept a good supply,” McCaleb said. “We probably have a 30-day supply at our current burn rate. But of course as patient numbers rise, so does the burn rate. And now we’ll be able to protect our staff.”
Tucker McCaleb identified COVID-19 as an envelope virus which is a single strand making it unstable. Wave lengths of 254 nanometers is the universal kill rate for viruses, so McCaleb and his dad chose the right strength and intensity that would account for burst strength, keeping all three layers of the mask in tact, flow resistance and maximum depth penetration.
“These are 15-watt bulbs and nine bulbs in the box,” Mike McCaleb said. “Theoretically, in one day’s time, we could sterilize every mask in the hospital.”
The box is a unique concept and Russell Medical said it’s willing to share the design with others.
To manufacture the device, Browning procured materials mostly from Home Depot and Thomas Auto Parts, except for the bulbs. He built the box out of 3/4-inch birch plywood with stainless steel handles for sanitary reasons. He installed hydraulic shocks to hold the lid open to load the masks and attached ballasts, which operate the bulbs, on the top of the box. The most vital feature is the safety switch he installed so the light bulbs will go off if the box is opened.
“The light bulbs won’t come on until you shut the door because the bulbs could be blinding and burn you,” Browning said. “When you shut the lid, the switch sends power to the ballasts and there’s an indicator light that let’s you know it’s on.”
There also is a reflective surface, which is covered in felt to absorb the energy that has to dissipate somewhere, McCaleb said.
As N95 masks are used, they will be collected in one room, picked up and zapped for sterilization before being returned and held in a clean room.
“COVID-19 is supposed to last on surfaces for about 72 hours, so as soon as the masks pile up, we’ll pick them up,” McCaleb said. “Other hospitals are attempting other sterilization methods but this is the safest and quickest method.
If it comes down to needing the emergency backup supply of sterilized masks, which will be cycled through the UV box at least three times, each employee will be given their own mask and personal identification number, so they are reusing the same one.
“We are so proud of this,” Foy said. “They just worked so hard to make this happen.”