Efficiency Meets the Pandemic: The Shortage of N95 Masks

N95 face maskOne hallmark of a market-driven economy is efficiency, i.e. manufacturing a product at the lowest cost. However, some problems exist with always being driven to reduce cost. One problem is that assigning cost to some factors is really hard; most notably in the cases of human life  and the environment.* However, I want to talk about another problem, namely the lack of resilience such an efficient system necessarily causes, using N95 masks as an illustrative example.   

“Just-in-time” manufacturing (the term “lean” manufacturing” is used today) was started in Japan in the 1960s and 1970s (primarily by Toyota) and was adopted by most companies worldwide by the 1990s. The fundamental idea is to produce only the amount of a good that can be sold immediately. The classic assembly line is the antithesis of this philosophy; the same amount is produced regardless of demand. In lean manufacturing, warehouses with excess product are eliminated or at least reduced in size significantly. If demand goes up, then production must increase to meet demand.   Using the car example, this would mean more cars should be manufactured in the summer than the winter since demand is higher in the summer. Limitations exist to this model in the extreme, but the basic principle guides most companies today. 

What does this have to do with the pandemic? Well a virus outbreak was a predictable event. In their 2017 essay, Madhav et al.  state that “Influenza is the most likely pathogen to cause a severe pandemic. Exceedance probability analysis indicates that in any given year, a 1 percent probability exists of an influenza pandemic that causes nearly 6 million pneumonia and influenza deaths or more globally.” (FYI: I am pretty sure COVID does not fulfill the 1% probability; the number of worldwide deaths are currently ~500,000 and I don’t believe 5.5 million people will die before the end of the year, or even before the end of next year). 

My employer has posted a document claiming mask wearing alone will reduce the spread of the virus by 85%.** The best masks for the prevention of virus spread are called N95 masks.  Current CDC guidelines state “The Centers for Disease Control and Prevention (CDC) does not recommend that the public wear N95 respirators to protect themselves from respiratory diseases, including coronavirus (COVID-19). Those are critical supplies that must continue to be reserved for health care workers and other medical first responders, as recommended by current CDC guidance.” Why is there a shortage of supply so that the public cannot use N95 masks? Such masks were available for purchase by the public before the pandemic. Further, N95 masks are still in short supply at medical care facilities while other critical supplies (ventilators, face shields, gloves, gowns etc.) seem to be in ample supply. What makes N95 masks so special?

Non-woven fabric produced by melt blowing

Part of the reason takes us back to the topic we were exploring several months ago: plastic. What makes N95 masks effective is that they use a mesh of plastic fibers to block even miniscule virus particles from passing through. But this involves an intricate process, melt blowing, by which the fibers are made for the masks. Melt blowing is very hard to control—it requires fibers to be the same diameter and have the same spatial distribution across the mask surface; otherwise the mask will be  defective. The technical challenge here is very hard; frankly, throwing money at this problem will not solve the problem in months. Years is a more realistic timeframe because the process is that hard to make work correctly. This long timeframe should not have been a surprise to anyone knowledgeable about how N95 masks are made.

And this takes me back to the question of just-in-time manufacturing. The problem with efficient supply chains is that if a significant change occurs, the supply chain has little or no ability to respond. One critical link can slow everything. In other sectors of the economy we have materials stockpiled, i.e. the strategic petroleum reserve, and likely soon minerals critical to modern electronics. What the Covid-19 crisis has proved is that the shift to lean manufacturing has meant that societies need to think about making a list of manufactured goods or parts that are both critical and consumable and hard to produce quickly. Those goods or parts should either be stockpiled or have idle machines that could quickly be started to meet the increased demand. Whether we as a society adopt such a course remains to be seen….***  


*How to compensate labor is an issue of course.  This issue is beyond the scope of this post though.

**There are many studies on the issue of how much masks reduce transmission of Covid 19.  Here is one that aggregated the results from many different studies.   To improve the amount of data analyzed, two other similar viruses, SARS and MERS, are included as well.    85% is the reduction value from this aggregation, but all masks (surgical, cloth and N95) were included and the authors also state that N95 masks are more effective.  However, the authors did not quantitatively separate by mask type in this aggregate compilation.

***This blog was written before the announcement by presumptive Democratic nominee Joe Biden proposed a plan to be sure the US does not face future shortages of critical equipment (click at the top right to skip the donation page). N95 masks are specifically mentioned.  

Brian Grady (ORCID 0000-0002-4975-8029) is Douglas and Hilda Bourne Chair in Chemical Engineering and Director of the School of Chemical, Biological and Materials Engineering at the University of Oklahoma.

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