Researcher, Faculty of Chemistry, University of Auckland

Joel Rindelaub does not work, consult, own shares, or obtain funds from any company or organization that will benefit from this article, and does not disclose any related affiliations other than academic appointments.

The University of Auckland provides funding as a member of The Conversation NZ.

The University of Auckland provides funding as a member of The Conversation AU.

As many children across the country are required to wear masks in classrooms, including children as young as 8 years old in Victoria, parents want to know how they can support their children in using masks.

School is a hotbed of respiratory viruses. This is the perfect way for aerosols to spread when a large number of people gather together for a long time in an indoor area.

In addition to proper ventilation, physical distance and good hygiene, masks can also help reduce the spread of COVID.

So what mask is best for children? How can children increase the likelihood that masks will protect them from COVID infection?

Read more: From vaccination to ventilation: 5 ways to protect children from COVID when the school reopens

The main way COVID spreads is through inhalation of infectious aerosols. When people with COVID cough, sneeze, talk or even breathe, they exhale a large number of tiny particles carrying the virus into the air that other people around can breathe.

Evidence from the United States suggests that wearing a mask in the classroom may reduce the chance of a child catching COVID from a classmate. The prevalence of children in areas with school mask regulations is about half that of areas without school masks.

Although there are no randomized clinical studies on the use of school masks, data from large community mask use trials supports their ability to reduce the number of symptomatic COVID cases in the community.

The World Health Organization recommends that students aged 12 or older and students aged 6 to 11 use masks under proper supervision.

Masks will not affect children's air exchange or their breathing ability, so they can be used safely. However, students who hide their specific needs should be evaluated based on their specific circumstances.

Masks are not recommended for children 5 years and younger, partly because facial expressions are important for social and emotional learning.

When choosing a mask, pay special attention to the fit; if worn improperly, the mask will lose most of its efficacy. There should not be any gaps around the nose or on the sides of the face.

Although many masks can prevent the infected person from releasing large droplets, a closer fit will improve the filtration of smaller aerosol particles.

Read more: Can't your child wear a mask? Here are 5 things you can try

Among the existing mask varieties, N95 or P2 type has the best filtration efficiency and can capture more than 95% of the particles. Although they need to be tested to ensure that they fit correctly in order to be most effective, they can be uncomfortable to wear for long periods of time.

Surgical masks (disposable masks that you can buy in supermarkets and pharmacies) are the next best filter, with an efficiency of 50-75%.

If you create a tighter fit around the face, for example, by wearing a surgical mask under a cloth mask, or by "knotting and wrinkling" methods, the efficiency of the surgical mask can be improved.

Although useful for older students, N95 and most surgical masks may not be as effective in protecting young children because many of these masks are designed for adults.

On the other hand, fabric varieties are usually more suitable for children. Being able to use interesting prints and colors can help children feel more comfortable when wearing masks.

However, due to the low filtration efficiency, the use of single-layer cloth masks is generally not recommended. A three-layer mask that fits is much better, and the effect is comparable to that of a surgical mask.

The recommended use of masks for children is the same as for adults, so:

Try to avoid touching the outside of the mask. This means using earhooks to put on and remove the mask. If the mask works effectively, there may be virus particles on the outside of the mask. Always wash or disinfect your hands after touching the mask

Use a separate bag for storage. It is important that the mask is not contaminated by other items or contaminated by other items

Make sure the mask covers the nose and mouth

The cloth mask must be washed after each use. A few cloth masks may be helpful, so you can use a fresh one every day

Throw away the surgical mask and N95 mask after each use

Do not use masks with valves. These will not prevent the infected person from spreading the virus.

Read more: 7 tips for making masks work in the classroom

Although the recommendations may feel relatively complicated, studies have shown that even children two years before school are very follow the mask guidelines, using them appropriately during an average of 77% of the school day.

In order to get the best results, when the school introduces the mask, it also needs instructions on the use and safety of the mask.

Wearing a mask during outdoor rest and rest is not important because outdoor areas are usually well ventilated.

In indoor areas where masks cannot be used, such as during lunch, encourage physical distance.

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