Our Ultra Masks and FilterTech Liners are tested by independent laboratories to provide 90% filtration of particles 0.1 microns in size as well as certain allergens and dust particles.During disease outbreaks like COVID-19, however, face masks alone will not prevent exposure. Consult the recommendations by the Centers for Disease Control and Prevention for tips on how to avoid person-to-person contact, practice social distancing, avoid touching the eyes, nose, and mouth, cover coughs and sneezes with tissue or the inside of the elbow, and frequently and thoroughly wash hands for at least 40 seconds.