Why use Ragweed Pollen To test filters?

Why Ragweed?

With all the different pollens in the world, why is ragweed pollen so important in testing filters?

Ragweed pollen is an airborne pollen, which means it primarily uses air currents as its method of distribution. Eighty percent of pollens are biotic which means they use other animals to move the pollen. Bees and bats and even birds are essential for the vast majority of plant life pollination. When testing an air filter, then, the focus is on airborne pollen.

Ragweed pollen is extremely light and extremely small. The average size of air borne pollen particulate is about 25 microns, while the average size of Ragweed pollen is 17 microns. When ragweed season comes, the pollen produced is practically everywhere. Ragweed pollen has been found over 15000 feet in altitude and four hundred miles out to sea. (1) 

Allergic reactions to ragweed pollen are very common, affecting millions of people. This is not to say that ragweed is the only pollen that triggers allergic reactions, but ragweed is often responsible both as a primary source and also as a source of cross-reactivity.

Finally Ragweed pollen is commercially available as a standard for testing labs. Standards are essential in scientific testing, so that filter efficiency can be tested and those tests can be replicated.

Ragweed pollen’s use as a standard reflects its widespread presence, the difficulty its small size presents, and its culpability in the suffering of so many people.

(1)  https://tpwd.texas.gov/publications/nonpwdpubs/young_naturalist/plants/airborne_pollen/

2 Common Questions About the Safeguard Window Filter

Each spring I field many questions about the Safeguard Window Filter. I would like to take the opportunity to address some of them here.  As I am sure many of you have these same questions. Today I will tackle the 2 most common ones: "Can I wash the Safeguard Window Filter?" and, "what particulate size can it filter out?"

Washing the Safeguard Window Filter:

Can we wash it?  In short the answer is No, don't do it.  Especially if you suffer from allergies.  The main reason is the potential for the filter media to shrink when it dries.  Which can create gaps around the edges of the filter allowing particulate to get around the filter and into your home.

What can you do to help extend the life of your window screen filter? The only thing we recommend (besides a replacement filter cartridge) is to vacuum the unit. This will help remove some of the larger particulate matter from the outside of the screen and help increase airflow. As you use the filter the pores will start to fill up, progressively increasing the filters efficiency (meaning the filter is blocking more particles).  At some point you will notice a dramatic decrease in airflow through the filter.  By vacuuming the filter, you can remove some of this particulate and thus extend its usefulness.

One note of warning: If you are highly allergic, you may want to vacuum the unit outside your home and as an additional precaution wear a dust mask.  Remember, what you are vacuuming off, is what was filtered out!

What Particulate Size does the unit filter?

I get this question a lot.  The reason, I believe is because HEPA filters are rated by particulate size and people want a comparison between HEPA filters and ours.  Unfortunately we have not tested our filter against the HEPA standards.  However our filter is tested for the most common type of allergen - Giant Ragweed Pollen (which is an industry standard test particle). In regards to particulate size, Giant Ragweed Pollen falls between 14 and 18 microns.  At that level, our filter (as of our last test) was rated at 98.8% efficient for removing Giant Ragweed Particles. Now, will the Safeguard Window Filter be effective with particulate size under 14 microns?  Logically speaking, yes it will, however it has not been tested and therefore we cannot make any claims about it.

Another question we receive relating to particulate size is: Why didn't you use a HEPA filter? Our answer is because HEPA filters are so fine they require forced airflow to function. The Safeguard Window Filter uses a passive air exchange.  If we were to use HEPA rated materials no air would pass through. There is a trade off between airflow and filtration capacity and we feel our current solution is the perfect combination.

If you have any questions you would like us to address here please let us know!  email us at info@repindustries.com and ask us to put up a post about your question!