Tests of masks marketed as N95 from 21 manufacturers show that half of Chinese N95 masks fail quality tests–with some masks filtering no better than a cotton cloth. These tests come at a time that many countries around the world are scrambling for masks and other PPE.
Factories Spring Up to Meet Mask Demand
Factories in China have popped up seemingly overnight to meet the demand. Amid the rush, the high prices masks are commanding have led to what The Wall Street Journal called a “wild west” for mask manufacturing.
Dozens of suppliers contacted Smart Air hawking everything from surgical masks to CE-certified FFP2 and N95 masks. Some suppliers even claimed they could make hundreds of thousands of masks a day.
Putting China’s New Masks to The Test
To find out just how well these masks are performing, we started contacting suppliers and testing their masks from the middle of April. In total, we tested 31 masks from 21 suppliers. The suppliers claimed their masks were N95 or KN95, meaning they filter 95% of particles (similar to the FFP2 standard in Europe). What we found shocked us.
We tested masks’ filtration efficiency using a method that resembled the “particulate filter efficiency” test in the official US test standard. The standard tests normally use a TSI 8130 machine that costs $95,000.
Our engineering team simulated this setup using three Met One particle counters (which cost about $5,000 each). This test provides a reasonable approximation of the official test, although it cannot be used to formally certify masks for government standards.
We adjusted the airflow to 85L/min to match the NIOSH test standard and measured the percentage of particles 0.3 microns and above the masks were capturing. In total, we tested two samples of each mask and repeated the filtration efficiency tests 3 times for each sample.
Most Chinese N95 Masks Fail Quality Tests
Out of the 31 masks tested, 13 Chinese N95 masks fail quality standards for filtration.
In other words, buying N95 masks in this new supply chain has odds of flipping a coin that buyers will actually get an N95 mask. To meet the N95 (US) or KN95 (China) requirement, masks need to capture 95% of particles. Yet only 18 masks managed to capture more than 95% of tiny particles.
What’s more, many of these failing masks were not just a few percentage points below the standard. On average, the masks that failed the tests captured just 51% of particles. The worst of the worst captured just 24% of particles, which is on par with the filtration ability of a bed sheet.
Masks Show Poor Quality in Straps, Stitching, Noseband
Next, we ran simple tests of the structural quality of the masks. These tests focused only on the masks that met the N95 standard. To start, we pulled the straps of each mask.
Straps on some models broke almost immediately. Straps failed on 11 out of 18 masks. Consequently, these masks are unlikely to last long, especially under conditions where healthcare workers are having to re-use masks.
Next, we tested the masks for fit. This revealed a common issue with the nose pieces and glue. Sub-standard glue meant that metal nose clips on some models came off quickly. In one model, the mask split open in the middle while the engineer was putting it on.
Why this matters: Longevity tests show masks remain effective after 30 days of use.
Only 7 masks – less than one-quarter – passed both the N95 filtration tests and these “wear and tear” tests. Thus, even masks that meet the N95 filtration standard may still prove useless.
New N95 Masks Made in Mobile Phone and IT Factories
To try to understand why so many masks were failing our tests, we did a background check on each of the 21 companies using a company directory for China.
Out of the 21 factories, we found that only 9 of the factories that sent us mask samples worked in the “health and medical” sectors. The other 12 operate in sectors such as mobile phone accessories, sports products, and even software & IT services.
Oddly enough, there was no correlation between factory sector and mask performance. This could be because the companies actually selling masks are just middle men and not actually producing the masks.
Non-medical companies sent us an average of two mask designs versus one for medical companies. Thus, the non-medical companies appear to be merely re-sellers.
New Moves May Help Clean Up Supply Chain
Recent moves may be helping the situation. In an attempt to limit the number of uncertified masks on the market, on April 10th, China tightened the checks on masks leaving the country. It remains to be seen whether these checks will prove useful.
Why we anonymized factory names: Because we tested masks from only a small handful of suppliers (21 in total), this data represents a fraction of all the companies making masks right now. Therefore, we didn’t set out to name and blame specific factories. Instead, we provide this data as a snapshot of the industry. For more information on the suppliers and tips on how to source reliable masks, check out our tips for sourcing N95 masks article.
As always, data at Smart Air is open source. Data and more details on the methodology are in the supplemental data article.
Paddy is the CEO of Smart Air, running operations from Beijing. He has a Masters in aeronautical engineering from Bristol University, UK having specialised in aerodynamics. An advocate for open data, free information and transparent business, he spends his spare time promoting honest business and social enterprise.