Determination of air parameters inside a face mask

Wearing a face mask became an everyday need and a safety measurement. Functionality and protective effectiveness of a face mask are the priority, but it is the air parameters that provide the comfort and ability to breate and live with a mask.

In this project no effects of a mask againt the viruses were determined. I focused on the determination of air parameters inside the mask, such as temperature, humidity and CO2 level and compared it to the outside temperature. I provided numerous experiments inside and outside an appartment to check the difference.

1. Hardware

I used a temperature sensor, humidity/temperature sensor and CO2 sensor for this project. Here is a photo of the sensors connected with an arduino uno (the shematics is added at the end of the description):

I used extra wires for two sensors to be able to put them inside the mask. The temperature sensor is used to get outside temperature, so it didn't need any elongation.

2. Software

I wrote a code in C++ to get the data from the sensors (the shematics is added at the end of the description). Here is a an example of a Serial Monitor with data:

3. Tests

For testing I chosed 3 types of face masks: 1) white mask with 50% polypropylene and 50% polyester; 2) blue medical mask with 50% spunbond and 50% meltblown; 3) white cotton mask with double layer.

I provided 5 experiments with each mask both inside and outside. I was checking the air parameters before wearing a mask and after 30 min of wearing each of them.

Here's the result of the experiments (average values):

According to the results, mask #1 showed the lowest level of CO2 both inside and outside, but the air temperature inside the mask increases by 13% (in comparison with air outside). The highest temperature rise (by 16%) showed the mask #2, but the level of CO2 stayed at low values. Mask #3 showed the highest values of CO2 level (by 16%). The humidity parameter stayed at almost 100% for all the masks.

Conclusions: Mask with double cotton layer has the highest CO2 level inside the mask, so it definitely has a problem with air exchange, which might lead to a headache or other symptoms correlated to the lack of oxygen. Medical mask has the highest temperature values inside, but the material of the mask can provide a good ventilation and CO2 level stays low. Mask with 50% polyester showed the lowest CO2 level, especially inside an appartment.