# Recharging and rejuvenation of decontaminated N95 masks

## TL;DR

This paper explores how to recharge N95 masks after decontamination to restore their filtration efficiency.

## Contribution

A simple setup is developed to measure and restore the charge in N95 masks after decontamination.

## Key findings

- A laboratory setup was developed to measure charge and filtration efficiency in N95 masks.
- Recharging decontaminated masks can recover their filtration efficiency.

## Abstract

N95 respirators comprise a critical part of the personal protective equipment used by
frontline health-care workers and are typically meant for one-time usage. However, the
recent COVID-19 pandemic has resulted in a serious shortage of these masks leading to a
worldwide effort to develop decontamination and re-use procedures. A major factor
contributing to the filtration efficiency of N95 masks is the presence of an intermediate
layer of charged polypropylene electret fibers that trap particles through electrostatic
or electrophoretic effects. This charge can degrade when the mask is used. Moreover,
simple decontamination procedures (e.g., use of alcohol) can degrade any remaining charge
from the polypropylene, thus severely impacting the filtration efficiency
post-decontamination. In this report, we summarize our results on the development of a
simple laboratory setup allowing measurement of charge and filtration efficiency in N95
masks. In particular, we propose and show that it is possible to recharge the masks
post-decontamination and recover filtration efficiency.