When faced with sub-optimal air quality, the typical solution for the individual has been some type of filter mask. While a wide variety of such masks are available, and can be very effective at removing unwanted contaminants from breathed air, wearing such masks has drawbacks. For example, many masks require greater breathing effort from the wearer to draw air through the filter material. There is also the possibility of discomfort, particularly if the mask is worn for an extended period of time. Accordingly, further improvements are possible.
USPTO Backgrounds
USPTO Backgrounds