For most people, masks to prevent COVID-19 are a simply a waste of money.

WHO says:

"If you are healthy, you only need to wear a mask if you are taking care of a person with suspected 2019-nCoV infection.

Wear a mask if you are coughing or sneezing."

https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public/when-and-how-to-use-masks

Or if you want the same thing said in a different way ...

https://www.who.int/docs/default-source/coronaviruse/2020-01-29-advice-on-the-use-of-masks.pdf?sfvrsn=dff15f8b_0&download=true

If you want to prevent transmission of COVID-19 then you can follow the advice on this page. I do.

https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public

Jamie