Dust or Pollen Allergy? Make Your Own Air Purifier | Allergy Test

There are plenty of reasons you might want to purify the air in your home. From dust, dander or pollen allergies, to local wildfires or even being in a polluted inner-city area – the air we breathe can be rife with unwanted particles (that can then lead to unwanted symptoms!). 

Environmental factors can play a huge role when it comes to allergies and intolerances, and cleaning up the air where you spend the most time is a great step towards a healthier you. 

How Air Purifiers Work

Air purifiers contain filters that remove particles from the air. These particles (or ‘particulate matter’) are composed of chemicals such as sulfates, nitrates, carbon, or mineral dust. Particulate matter is often found in burning organic matter, like fire smoke.

A particular kind of particulate matter found in wildfire smoke PM2.5 — it’s extremely fine, being 30 times thinner than the average human hair.

This particulate can be inhaled into our respiratory tract and then travel deep into our lung tissue. Consequently, this can contribute to health problems, including cardiovascular and respiratory disease.

Smoke from wildfires, in particular, have been shown to increase the risk of:

  • asthma
  • bronchitis
  • eye irritation
  • cardiac and pulmonary conditions

Exposure can also cause short-term effects, including:

  • coughing
  • sneezing
  • shortness of breath
  • runny nose
  • throat or nose irritation

One study from 2008 demonstrated that remaining indoors while using an air cleaner can effectively reduce PM2.5 exposure.


study from 2015 indicated that for air filters to work effectively, they need airflow to ensure adequate ventilation. They should also effectively filter out various small particle sizes, including the aforementioned PM2.5.

Many air purifiers contain High-Efficiency Particulate Air (HEPA) filters, which remove most airborne particles via mechanical filtration.

Other high-quality filters, like those with Minimum Efficiency Reporting Values (MERV) ratings, will work too. But the higher the rating, the more effective the filter. We’d recommend aiming for a rating of 11 or higher.

HEPA filters are standardized at a minimum of 99.97% efficiency rating for filtering particles which are greater than or equal to 0.3 micrometres in diameter. That’s a diameter of just 1/83,000 of an inch!

So for every 10,000 particles that are 0.3 μm in diameter, 3 will pass through the filter, and the rest will be trapped—thus making HEPA filters the best choice for DIY air purifiers, as they filter out those ultrafine particulates, such as those in fire smoke.

Room Size

It’s important to be aware of room size. Homemade air purifiers are good for small rooms of up to 10 by 10 feet. But, they won’t do the job if the room is much larger.

You’ll want to situate your air purifier where you spend the most time, whether it’s the living room, bedroom or office space. You could have multiple purifiers in each room of the house if you want.

If you only have the means to make one air purifier, just pick one room. Maintaining good air quality in a small space is far easier to manage than an entire house.

Build Your Own Box Fan Air Purifier

You’re going to need a box fan. It’s best to aim for 20 by 20 inches, but any size that your filter sufficiently covers will work.

What you’ll need:

  • duct tape
  • utility knife or scarf scissors
  • two 20-by-20-inch HEPA or another high-quality filter
  • 20-by-20-inch box fan
  • cardboard (you can use the box the filters come in)

How to build:

  1. Unbox the filters while keeping the cardboard as intact as possible. Try not to puncture the filters inside with your scissors or knife.
  2. Lay the two filters on top of each other with the black carbon sides facing each other. The airflow arrows (or labels) should now point towards each other.
  3. Securely tape the filters together on one side – creating a hinge when opened.
  4. Next, lay the box fan face down on a flat surface and place the filters on top. The two non-taped sides should meet the edge of the fan now. Tape them in place.
  5. Fill the empty triangular space made by attaching the cupboard. To do this, first, place the cupboard on the top and bottom of the filters. Use a pen or pencil to mark where the cupboard meets the filters and box fan.
  6. Now, cut the cupboard and attach it to the box fan and filters with tape.
  7. Seal any gaps on your device using additional duct tape.
  8. Finally, place it in your desired location, ensuring there aren’t any obstructions to airflow.

Safety Notice: A DIY filter does have increased potential for fire risk. So, only use an improvised device when someone is around to keep an eye on it. You should never leave a DIY air filter on unattended.

Final Thoughts

A DIY option to purify your home can be a great alternative if retail stores are out of stock, especially if you’re suffering from an unavoidable dust mite or pet dander allergy.  

You only need a few materials but remember to get a HEPA filter or filter with a high rating, or your air purifier may not be effective. If used in small rooms with doors and windows closed, homemade air purifiers can help to markedly improve your homes’ air quality.