In Order to have clean air which it means free from all viruses in this beautiful world many people do different things to make preventive action such having masks. From Proper manufactured masks until DIY masks.
In the rush to make homemade masks, many people are wondering whether non-woven polypropylene bags are effective at filtering viruses. These bags are incredibly popular in places like Asia and Africa, where they are a common alternative to flimsy plastic shopping bags. These shopping bags are great candidates for masks because they were durable, stores often give them away for free, they are easy to find. In fact, in some African countries, markets hand them out for free to all shoppers. These bags in Uganda are real-life examples. Thus, the bags are promising candidates, but how well do they filter out virus-sized particles? Can they really protect the wearer from viruses like the SARS-CoV-2 coronavirus?
Reusable tote bags are made from a non-woven, polypropylene plastic (often referred to as PP). Woven materials are easy to understand. Cotton threads in things like pillow cases are woven together. The non-woven in the name means the plastic is bonded together. One way to do that is to melt the plastic so that it forms together. For example, imagine taking a handful of chocolate chips and melting them into a bar. Non-woven polypropylene plastic is also the material used to make masks and HEPA filters. Since masks and HEPA filters can both capture the coronavirus, it would be reasonable to think that these bags might too. Thus, we put it to the test.
In the lab, we tested 30 DIY materials including a polypropylene bag to see how well they these DIY mask materials could filter out virus-sized particles. We measured the ability of the polypropylene bag and other materials to capture 0.3-micron particles and 1-micron particles. The SARS-CoV-2 coronavirus measures 0.06-0.14 microns by itself and 5-10 microns when in water droplets. The polypropylene bag captured 22% of the smaller particles and 42% of the larger particles. Next, we tested whether adding more layers would significantly increase effectiveness. The data showed that two layers of non-woven shopping bag material filtered 34% of small particles. Three layers more than doubled the particle capture. How does that compare to masks? Effectiveness of 57% is not bad, but it is still a far cry from the 97% the surgical mask we tested was able to capture. Out of the 30 materials we tested, the polypropylene bag did not capture the most particles. However, it was one of the most breathable materials. A single layer bag was more breathable than a surgical mask and about as breathable as a 100% cotton T-shirt and bandana. Because it is so breathable, polypropylene can form three layers and still be more breathable than a surgical mask. Thus, a triple-layer non-woven polypropylene mask makes a great candidate for homemade mask material.
Data shows that polypropylene bags are worse than surgical masks at capturing virus-sized particles. However, the high breathability of polypropylene bags means they can be layered up to make more effective DIY masks, although they still do not come close to the performance of a surgical mask.