Humidity, a lot of how air temperature “feels” comes from the water in the air, when you breath through fabric some of the water isn’t getting into your mouth.
Secondly, the amount of effort required to breath through fabric is more than normal so the air feels colder, try blowing onto your hand with your lips in a tight “O” shape compared to open mouthed to get an idea of how pressure effects temperature.
Humidity, a lot of how air temperature “feels” comes from the water in the air, when you breath through fabric some of the water isn’t getting into your mouth.
Secondly, the amount of effort required to breath through fabric is more than normal so the air feels colder, try blowing onto your hand with your lips in a tight “O” shape compared to open mouthed to get an idea of how pressure effects temperature.