These have been around for at least 15 years, and the manufacturer never bothered to try and improve them. The air flow through filters these is severely reduced. It makes sense, since the surface area of certified activated-charcoal non-woven respirator filters is at least 100x large. These filters are no OSHA etc certified and do not show any test results for particulate sizes. Assuming that the membrane does block the VOCs and the particulates (although there are no data provided), these might help for 5-10 min at a time, if the only alternative is to hold one's breath. Otherwise, get a proper respirator: you get 100x more filtration surface, proper respirators are certfied, and you get many days of service. Or, if you must use nasal filters, look for reticulated foam ones (but do not count on them being even within 10x of efficiency of proper respirators).

I found that the Nasal Air Guard filters are difficult to insert into the nostrils and tend to tilt. They are hard and uncomfortable and just don't seem to be nostril shaped, being flat at the top. I found I could hardly breathe through them and was very disappointed with this product.