American researchers use BINDER drying chambers

June 2020 Decontamination of N95 masks

Developing effective decontamination methods for N95 masks


During this COVID-19 pandemic, teams of scientists from multiple American universities are collaborating to compare the effectiveness of different decontamination methodologies for N95 masks. There has been a critical shortage due to the sky rocketing demand for health care professionals to obtain N95 masks. In a non-crisis situation this personal protective equipment (PPE) was designed for a single use only. The reality is healthcare professionals do not have sufficient supply of N95 masks for single use as directed by the Center of Disease Control and Prevention (CDC). Only in a crisis situation does the CDC allow healthcare professionals to deviate from this strict guidance. Some people believe dry heat is effective other people believe heat and humidity is effective. There are in fact different ways to decontaminate the N95 masks, the quest for researchers is identifying the effectiveness of each method. Unfortunately, the COVID-19 has created the crisis environment which also created the need to research decontamination methods for reuse of N95 masks.


BINDER GmbH, a global manufacturer of environmental simulation chambers, is working with US universities to prove the efficacy of decontaminating N95 masks using heat with relative humidity. As early as mid-March, research teams have been studying ways to reuse this vital facial protection for both emergency responders and the public health professionals. The research suggests the following method: The N95 respirators which are normally used just once can be decontaminated. The N95 mask can be placed in a drying oven with a moist cloth for 30 minutes at 65 C° to 70 C° (149 F to 158 F). The increase in temperature and humidity for 30 minutes can mitigate the risk of contracting COVID-19 when reusing the N95 mask.   The decontamination process lowers the chance of exposing health care professionals to COVID-19 virus when reusing the N95 mask more than once.   The preliminary results from scientists are promising for the decontamination process using heat with relative humidity being effective. Testing has shown that the N95 mask filter is still effective up to five decontamination cycles at 60 °C and 80% relative humidity.  Also, the mask fit was still acceptable after a decontamination cycle which is very important for the actual mask users. Without proper fitting of the N95 masks the usefulness is dramatically decreased. This important research will hopefully show there can be successful decontamination methods developed for the reuse of N95 face masks.


Scientists are identifying the best temperature and relative humidity % which would be needed to decontaminate N95 face masks. The researchers placed the N95 mask into individual plastic containers with a wet towel to produce the necessary relative humidity.  Up to 20 to 25 containers were placed in the drying ovens for each decontamination cycle. Multiple drying ovens have been sent to different US universities for this research. Each team of researchers is working on different aspects of how decontamination methodologies are affecting the N95 mask. While one team focuses on the structural integrity another research team will research if the virus is inactive after the decontamination process.


The current result: Temperature and relative humidity are both critical factors for effective decontamination of N95 masks. The decontamination cycles were effective up to five times. Scientists focused on tests to determine if the filter was still effective and if the face mask fit was still fitting for users. A point which is also very important in the protection against COVID-19.


“BINDER is dedicated to providing researchers with high quality products to develop decontamination methods for N-95 masks. Given the current global crisis we are hopeful that the teams of researchers using our products find a solution to help keep of health care profession safe and healthy in there fight against the COVID-19 virus”, says Eric Swertfeger, the General Manager of BINDER Inc.


With the current COVID-19 pandemic ongoing researchers will continue to develop new solutions for today’s problems. By combining the resources of the private and public sector new developments are coming to market at record pace. While the decontamination methods of N95 masks will not provide a vaccine, it will help keep the health care professionals combating the COVID-19 virus safer.