The use of masks in the face of the coronavirus continues to be controversial. Researchers and doctors basically agree that homemade fabric masks offer little, if any, protection against pathogens. Others point out the fact that these masks are really useful in preventing the transmission of the virus by infected people, with or without symptoms. The fact is, that the demand for masks has exploded, causing a worldwide shortage. That is the reason why so many people started making homemade protective masks.
One of the latest ideas is about a DIY Hepa filter face mask. However, could a homemade mask with Hepa filter help in the fight against coronavirus? Is it an effective protection? We shall take a close look at the question and explain how you can make a Hepa filter face mask for multiple use.
DIY Hepa filter face mask: can it really filter aerosols from the air?
In general, medical professionals wear two types of protective masks. The first is a disposable breathing mask called the N95. It is a respiratory protective mask that protects the wearer by filtering out infectious aerosols, such as droplets from sneezing and coughing. It is only intended for medical staff and other workers who come into contact with sick people. It is not used by infected people who would like to avoid infecting other people. This type of face mask is particularly effective against respiratory diseases such as COVID-19. It can filter up to 95% of the aerosols from the air and retains over 99% of the pathogens. To be effective, it must be properly adjusted to the face and completely covers the mouth and nose. This mask is for single use and should be changed after a high risk exposure.
The second type is the surgical mask. It is designed to minimize the transfer of bacteria and particles from one person to another. This type of mask can be worn by healthcare professionals as well as by contagious patients. Typically, this type of mask is worn by surgeons during surgery to prevent smear and droplet infections and to protect the patient from viruses and bacteria. As with any type of mask, it must be correctly positioned on the face in order to be effective.
As a reminder, the wearing of masks is compulsory for sick people, and recommended for those who care for the sick. As part of the fight against the spread of coronavirus, everyone is encouraged to purchase masks. Faced with the shortage, you have to be creative and make protective masks from household items or sew a face mask. T-shirts and bed linen help us make the masks ourselves, while paper towels and dry wet wipes serve as filters. However, homemade masks offer only limited, if any, protection. That’s why most people are looking for a filter for their DIY masks. There are no studies available that can really confirm the protective effect of paper towels and dry wet wipes as filters.
Recently, the question whether Hepa filters could effectively protect against viruses and bacteria has arisen. First, let’s explain what a Hepa filter is. It is a particle filter that can effectively filter even small particles from the air. Hepa filter was developed to filter poles, dust and mites and to keep them in the vacuum cleaner. At the same time, the filters let the air through. This means that they are practically permeable to air and that theoretically people can also breathe.
These filters are also called absolute filters or THE (Very High Efficiency) filters. They can be used in difficult conditions such as very high temperatures (up to 370°C), high humidity, radioactive environments etc. All Hepa filters must meet a well-defined European standard, which classifies them into different categories, depending on their effectiveness. All filters that filter the air to 99.98% are called Hepa. All filters that filter the air up to 99.97% of the air are called EPA.
What types of Hepa filters are available on the market?
There are several types of Hepa filters that comply with the European standard EN1822 and the American standard MIL:
- EU 10 or H 10 are filters that are able to filter up to 85% of fine particles. These filters are not sold in the United States.
- EU 11 and H 11 are filters capable of filtering more than 95% of fine particles from the air. In the United States, they are only called 95%.
- EU 12 or H 12 filters also meet the standard and can effectively filter up to 99.97% of fine particles.
- EU13 / H 13 and EU 14 / H 14 are Hepa filters that can filter more than 99.99 fine particles. These filters are usually recommended for allergy sufferers.
In theory, Hepa filters can filter even the microscopic particles of the coronavirus although currently there are no studies to prove it. It remains unclear if a mask with Hepa filter can offer an effective protection against COVID-19. But at least it filters better than a fabric mask, for example.
It is also unclear whether breathing through a Hepa filter is harmless to health. But since filters like this are built into vacuum cleaners and are even recommended for allergy sufferers, it could be assumed that they improve air quality and cannot harm health.
Anyone who wants to make a face mask with Hepa filter should still always seek advice from the local health authorities or their family doctor.
Babies and toddlers are not allowed to wear homemade masks. As a rule, children are only allowed to wear a respiratory protection mask after consultation with the pediatrician. Babies are generally not allowed to wear a face mask anyway, as there is a risk of suffocation.
Making your own filter mask with Hepa filter is quite simple. First, you need to get an EU13 or EU14 filter. Trim the ends and remove the Hepa filter cloth. It is possible to notice pieces, resembling cords of hot glue, which are used to hold all the folds of the fabric together. These “cords” must be carefully retained to obtain a long strip of Hepa fabric. Cut out a 15cm x 20cm rectangle. Make 4 folds of about 1 cm, distributing them evenly. To make it easier, use a few alligator clips. Now all you have to do is sew the folds. Your Hepa filter is ready and you can insert it into a homemade mask made of fabric.
You can fix the folds with clothespins
You can sew the filter by machine or by hand