Right now, according to the WHO, you don't need to wear a mask at all (indoor) times like we are all being told:
If you are healthy, you only need to wear a mask if you are taking care of a person with COVID-19.
Wear a mask if you are coughing or sneezing.
Masks are effective only when used in combination with frequent hand-cleaning with alcohol-based hand rub or soap and water.
If you wear a mask, then you must know how to use it and dispose of it properly.

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