The challenge faced in the US and globally today is the shortage of both meltblown fabrics (the most critical component of the mask) and the converting capacity.
In response, NWI has developed an N95 meltblown filter medium and will be producing and offering the material to partners for use in N95 molded masks as well as surgical masks. But, that may not be sufficient.
One question that comes up is: How About Reusable Masks?
This is an interesting question and CDC has solicited proposals in the last decade or so targeted at reusable masks or masks that can be re-sterilized.
The challenge is how to recharge the mask after laundry or sterilization… And, what structures can be used to form a structure that can be decontaminated and reused without losing performance?
This is an area that the Nonwovens Institute has spent a lot of effort developing. The material is a structure that is bonded by hydroentangling and can offer pressure drops in the range of what you find for most facemasks (15 to 45 Pascals). The efficiency is in the range of 80 to 85% for a single layer, and is durable, and can be reused if decontaminated by appropriate methods. We note that the structure does not lose its efficiency after exposure to alcohol.
|Pressure Drop (Pa)|
|One layer||As Received||82.2||15.6|
|Two layers||As Received||95.5||30.1|
|Three layers||As Received||99.8||46.6|
We believe that in this time of crisis, a properly-designed reusable mask may be worthwhile to consider and while it may not reach the performance levels of the N95, they still provide a significant level of protection to the public. FDA just announced guidelines for non-regulated masks.
An alternative that was just unveiled in Korea is also an option. This combined a reusable concept together with an insert – the insert is a high efficiency meltblown fabric similar to what is used in N95 masks but has a much smaller footprint, and therefore, one meter of meltblown fabric will make many more than 25 or 30 masks using the current structures.
What if the current crisis continues beyond the months of April and May? The strategies would include the following short term and longer-term options. And, it is important to allow new structures that may not have the FDA or NIOSH approval in hand. This is not to say that we should compromise quality but allow the use of non-certified masks that meet the pressure drop and efficiency requirements of the certified masks documented by a 3rd party certified lab. FDA recently published guidelines that must be strictly followed.
The Nonwovens Institute stands ready to help with the current crisis and will be happy to engage in a dialog. NWI has redirected ALL of its efforts to forming filter media for the current crisis.