DIY Air Filters for a Healthier Home

Making your own air filters at home can be a cost-effective and healthier alternative to traditional store-bought options. According to research, air purifiers can reduce airborne pollutants by up to 99.97% when used correctly.

Using a HEPA filter is a great way to start. HEPA filters are designed to capture 99.97% of particles as small as 0.3 microns, including dust, pollen, and other allergens.

To build a DIY air filter, you'll need a few key materials. Four MERV 13 filters are a must-have, and it's essential to choose two-inch filters for this project.

You'll also need a box fan, which will serve as the core of your air filter. The box fan's packaging or similar cardboard will come in handy for additional support.

Duct tape is another crucial item, as you'll need to use a lot of it to seal up the edges around the fan and ensure that air flows through the filter media. Scissors will also be necessary for cutting the cardboard and any other materials you might need.

Here are the materials you'll need to get started:

To get started on building your DIY air filter, you'll need the right materials. You'll want to gather four two-inch MERV 13 filters, which are essential for effective air filtration.

A 20-inch box fan will serve as the base of your air filter. You can repurpose the cardboard from the fan's packaging to create a sturdy base. Duct tape is also a must-have, as you'll need it to seal all the edges around the fans to prevent air from escaping.

Here's a list of the materials you'll need:

You can also use bungee cord or tape to secure the filter in place, as mentioned in another DIY air filter project.

A prefilter screen is a simple yet effective way to keep pet hair out of your filters and prolong their useful life.

This modification can result in barely noticeable flow reduction, as seen in one example where the flow reduction was only 1.27%.

The screen material used is usually fiberglass, which is an economical option that doesn't impede flow.

One option for fiberglass screens is the Adfors mesh, which has a mesh of 18×16 per inch and a diameter of 0.011.

Curious to learn more? Check out: Furnace Filters and Air Flow

The Ford Motor Company and Lasko Products, LLC developed a DIY air filtration kit that was shipped to organizations in underserved communities.

The kit consisted of a cardboard box, a 20" box fan, and a MERV 13 filter.

Dr. Richard Corsi and Jim Rosenthal created an air filtration unit made with five filters taped together to form a cube with a box fan taped to the top, dubbed the "Corsi-Rosenthal Box" or CR Box.

This design reduced airflow resistance and increased the amount of air flowing through the filtration unit.

A four-filter version of the unit was tested, dubbed the "Comparetto Cube".

NIOSH researchers purchased and evaluated seven box style fans based on commercial availability, using two fans with the highest and lowest airflow rates in the DIY unit configurations.

Each model was constructed using commercially available 1" or 2" deep MERV 13 filters.

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The Corsi-Rosenthal box performs very well, making it the most cost-effective air cleaner on Marwa Zaatari's chart. It's a DIY solution that's optimized for maximum effectiveness.

The CR box uses a single filter, but using a full cube would be even better. This setup is consistent with ASHRAE guidance on upgrading filters and using portable air cleaners.

According to the chart, the CR box is more cost-effective than popular air purifiers like Intellipure and Blueair. It's also a more affordable option than needle point bp ionization.

The CR box is not specifically mentioned in ASHRAE guidance, but it meets their requirements for effectiveness and safety. This makes it a reliable option for mitigating airborne exposure to Covid-19.

Johns Hopkins also recommends using DIY air cleaners like the CR box to reduce the spread of Covid-19. They're listed in the "Ventilation: Vital Tool to Reduce Spread" paper as a viable solution.

Check this out: Corsi–Rosenthal Box

DIY air filtration units can be a temporary solution until you can get a commercial portable air cleaner, but they shouldn't be used long-term.

It's essential to use high-quality MERV-13 filters, which are more effective at filtering smaller airborne particles than lower-rated filters.

Using 2" filters in your DIY unit will give you better performance than using 1" filters.

The more filters or thicker filters you use, the better your unit will perform.

Increasing airflow is key to effective filtration, so use the highest airflow possible.

A fan shroud is a must-have for your DIY unit, as it prevents air from recirculating and improves performance.

Make sure all joints and holes are sealed to prevent leaks and ensure your unit works efficiently.

Here's a quick rundown of the DIY unit tips: