Review on 🌬️ 4WDKING Rechargeable HEPA Filter Air Purifier: Portable & Reusable for Outdoor Sports, Sleep, Housework by Laurance Kim

Warnings Not designed to protect against viruses. The activated air creates a positive pressure that exacerbates the fatal flaw with all face masks, leakage of unfiltered exhalation. Thus, the owner gets a lot of filtered air, but increases the risk of exposure to others. We try to mitigate this and minimize leaks with simple mods that enhance each mask. Secure the mask to your face using any mask frame, a homemade mounting frame made from 1/2" garden zip ties, and the most efficient 8-10" nylon pantyhose tubing used for the entire mask. The inside edge is cropped, especially around the arch. We add a standard mask outlet valve with filter material on the inside of the valve to provide lower bypass pressure. Every mask with an outlet valve must have a filter material on the inside. Otherwise, it is just a device for concentrating and fighting viruses. All brands claim hepa filter h13. Some filters are Niosh or China certified. We add a layer of Merv 16 Filti face mask material from filti.com or one of the electrostatically blown polypropylenes available here on Amazon over the HEPA filter. Aside from filter quality control issues, mismatched materials, or invisible defects in these tiny HEPA filters, we believe it is a necessary redundancy to filter viruses. This will likely bring filtration to N99 levels and reduce airflow by 10-15%. We modified all 4 brands for mask intolerant, exercise intensive and high intensity wearers. The functional difference between the brands is negligible. The Airdog has a round shape and is also a small tabletop device. Simple Benefits. Models with a KN95 mask work very well for most faces. An excellent source of fresh air for smoke and pollutants. moderate physical activity. They make a great addition without a snorkel worn around the neck and let filtered cool air through when wearing a regular mask under a face shield. All materials except the Filti nano filter material are available on Amazon. A sophisticated negative/positive electric control valve would make them advanced lifesavers that deserve a lot more than a cotton bandana.