COVID-19 is testing the limits of many supply chains in the medical industry. One of the biggest spikes in demand has been in the personal protection equipment (PPE) industry. Because of the high rate of infection of the coronavirus, hospitals are finding shortages in PPE, the most important of which are N95 masks. A few months ago, you could walk into any Home Depot and buy as many N95 masks as you wanted. Like many other things, a lot has changed recently.
Dr. Eric Schnell is an Associate Professor of anesthesiology and perioperative medicine at OHSU and the Veterans Hospital. As an anesthesiologist, Schnell is involved with many surgeries, and due to COVID, his work is changing. “We try to avoid doing surgery on COVID positive patients,” he says. Like most doctors during the pandemic, he has been working very hard. For the last few weeks, he has been spending between 80 and 90 hours working.
While he works with patients at the VA, he also runs a lab at OHSU, where he mainly conducts neuroscience research. More recently, though, he has been dedicating his time towards a solution for the decontamination of masks. Recently, N95 masks have become essential to the wellbeing of healthcare workers, because of their ability to filter out air particles that could include the coronavirus. This is unlike surgical or face masks, which according to the CDC can only filter out larger air particles, and fit more loosely onto the face. Mask shortages are not a completely new problem, and mask decontamination became a practice after the SARS pandemic of 2003. This resulted in a lot of research towards the decontamination of masks, and many strategies of decontamination were tested. There are many different ways to sterilize a mask, but many are harmful to the mask as well, which damages the mask’s functionality.
Schnell’s lab has been working with two different methods: shortwave ultraviolet light (UV-C), as well as vaporized hydrogen peroxide. Both these methods accomplish the same thing: kill all the bacteria and viruses living on the masks with as little harm to the masks as possible. Each method has its own pros and cons. Schnell says he started mainly with UV-C decontamination because it is a much more accessible method that requires only readily available equipment. “It was pretty easy to build because most hospitals have UV-C lights floating around already,” he said. While both techniques require a dedicated room, the UV-C method does not need nearly as many safety precautions. In order to find the correct amount of UV-C exposure that kills everything but doesn’t damage the masks, Schnell and his team used a special UV light meter. The masks are suspended in a room surrounded by the UV-C light bulbs and are exposed for around a half an hour to become decontaminated. Adding in the time for loading and unloading the masks, this technique can decontaminate around 40 masks every hour.
The other method, vaporized hydrogen peroxide, can process up to around 2000 masks every 3-hour cycle, but it comes with other problems. The equipment used to vaporize the hydrogen peroxide can cost up to $100,000. In addition, there are only a few companies that make these devices, and they are struggling under the demand during the pandemic. Even once a hospital gets their hands on such a device, they still must construct a special air-tight room, because hydrogen peroxide in its vapor form is lethal not only to organisms but to people as well. Fortunately, unlike other gasses capable of sterilization, hydrogen peroxide vapor breaks down into oxygen and water and becomes completely harmless after a few hours.
Schnell explains that the construction and the necessary training to operate a hydrogen peroxide room safely is “out of reach for a lot of developing countries where resources, money, etc, are very hard to get.” The current state of the healthcare system in the United States is nothing compared to the situation in developing countries, who usually rely completely on other countries to acquire things such as PPE, which is a huge problem when the supplying countries are short on PPE themselves. So, while hydrogen peroxide is a more efficient method for large, developed hospitals, for smaller hospitals in undeveloped countries it is much less expensive to buy UV bulbs and light meters to sanitize their masks this way. Schnell and his team realized this and wrote up their research on UV methods for sanitization, which can be found here.
Both methods greatly increase the lifespan of masks. With hydrogen peroxide, Schnell’s team has found masks to withstand up to 20 cycles. With UV light, masks can stand up to 10. He says that just wearing a mask for an extended period “probably does way more damage to the masks and their subsequent performance than either decontamination methods.” Because of this Schnell says he has been working with hospital workers to be more gentle on their masks.
While OHSU currently has enough new masks to supply the hospital, Schnell’s research and testing could become crucial to the health and safety of OHSU’s workers in the coming months. While Schnell explains that new masks will always have an advantage over decontaminated masks, sterilization practices such as these could be very helpful for reducing hospital waste in the coming years as well. In the meantime, Schnell’s team will be storing decontaminated masks for when they are needed.
