We keep a box fan with a furnace filter on it in our bedroom so we breath clean air all night.
You can make this simple air purifier with a 20” Box Fan $20 + 20” Merv 8 Furnace Filter $7 + Box Fan Filter Grip $12 = $39 Total
Box Fan Filter Grip is a new product on Amazon that allows you to turn a 20” box fan and 20" furnace filter into an air cleaner/purifier.
The Box Fan Filter Grip consists of 2 Silicone bands that are sized correctly to hold a 1” x 20” x 20” furnace type filter to a typical 20” x 20” box fan. The silicone used is a proprietary formula that resists UV rays and ozone. The grips work best on a box fan that has the electrical cord coming out of the bottom of the fan. This way the cord will not interfere with the filter insuring a more secure fit. Box fans are available online and at many different retailers.
When selecting a filter, it is best to use a 1” x 20” x 20”. This will give the best results. Filters are manufactured with different levels of filtration. If you are wanting to filter out the most common allergens, purchase a filter with a MERV 8* rating or higher. If you only want to reduce dust in a workshop for instance a lower rating would work. Filters like these are available online and at many different retailers.
*MERV stands for Minimum Efficiency Reporting Value. This rating system was developed by the American Society of Heating, Refrigeration and Air Conditioner Engineers.
MERV values vary from 1 to 16. The higher the MERV value the more efficient the filter will be in trapping airborne particles.
go to amazon.com and in the search window type... Box Fan Filter Grip
or click on the link below