You can follow 4 simple steps to test if your mask is well sealed to protect you:
1. Put on the mask. Make sure the metal strip is bent tightly around your nose.
2. If the mask has two straps, make sure one strap is below your ears and one above.
3. Lightly hold the mask in place and inhale sharply. While inhaling, pay attention to see if you feel a sensation of air or coolness around the edge of the mask. Pay particular attention to the area around the nose.
4. If you feel air leaking, adjust the mask and try again. If further adjustment does not solve the problem, try a different mask.
Click here to see the article with demo pictures: https://smartairfilters.com/en/blog/poor-mans-fit-test/