wear them over your nose.... and the reason to wear them is to make a barrier so
don't stand in front of me with a big hole in your mask in the front..
Masks with Exhalation Valves or Vents
The purpose of masks is to keep respiratory droplets from reaching others to aid with source control. However, masks with one-way valves or vents allow air to be exhaled through a hole in the material, which can result in expelled respiratory droplets that can reach others. This type of mask does not prevent the person wearing the mask from transmitting COVID-19 to others. Therefore, CDC does not recommend using masks for source control if they have an exhalation valve or vent.