DIY PURIFIERS

You can make your own using a box fan with a square or rectangular housing and a MERV-13 filter that is the same area as the fan. This is called a box fan filter, and you can build one for about $45. Note that box fan filters are expensive to run over a 5-year period because of electricity use and filter replacement costs. Box fan filters can also be pretty loud to operate, so it may be better to buy one of the suggested air purifiers instead, even if they are more expensive up front. 

Here are the steps to make one:

1. Place the filter on the back (air intake side) of the fan. 

2. Use duct tape or bungee cords to attach the filter securely to the fan. 

3. Like a regular purifier, place in an area away from your wall and turn the fan on.

4. Keep all windows and doors closed.