The air you breathe in your car or truck is potentially some of the worst you will encounter on a daily basis. The relatively small cabin volume and proximity of the driver and other passengers make for one of the highest risk environments for the transmission of an airborne disease.

Opening windows is always a great option, but there are times when that is not possible. Plus you bring in lots of allergens and other airborne particles. There is a simple, low-cost solution – Mini-Mini Corsi-Rosenthal Box. For $40 to $50 and 15 minutes of your time you can dramatically lower those potentially dangerous indoor particles.

Here is what you will need –

1. 4 – 6″X6″X1 MERV 13 Air Filters

2. Two pieces of 6 1/2″ X 6 1/2″ cardboard – one with hole cut slightly smaller than PC Fan

3. Duct Tape

4. Utility Knife

5. PC Fan compatible with USB Port

Start by building the box with the 4 – 6″X6″X1″ filters. Make sure the airflow arrows are pointed towards the center of the box. I use a small piece of tape at each joint to hold the box together while I do the rest of the taping.

Next tape up all of the seams between filters and tape on the bottom and top of the box. The key is a make sure you use enough tape to ensure a good seal.

The final step is to add the fan. It can be taped to the top of the box. I used Velcro so that it can be easily disassembled for packing.

The choice of PC fan is totally up to the builder. I selected a two-fan system to have some extra power. I will add recommendations of other PC fans to this article as they are received. This two-fan set-up produces about 30 cfm.

Since it connects to a USB port, it can be used almost anywhere. But at this level of cfm it is perfect for a car or truck. It is very quiet, uses minimal power and is portable. I have been running it off of a small rechargeable battery pack for several hours.

So, let’s do a little test and see how the Mini-Mini performs. I used my Volvo XC90 with three rows of seats and an interior volume of about 120 cubic feet. That means that the Mini-Mini should achieve about 15 ACH (which is pretty impressive considering a hospital isolation room has 12 ACH). I was in the driver’s seat with the motor running and the heat on (not on recirc). I placed the MM box on the back seat. Within 5 minutes there were reductions in 0.3 um particles of 88%, of 0.5 um particles of 88%, 1 um particles of 93% and 2.5 um particles of 88%. A second test found reductions of 81% at 0.3 um, 82% at 0.5 um, 88% at 1 um and 76% at 2.5 um after 5 minutes. It is pretty safe to say that the Mini-Mini Corsi-Rosenthal Box would reduce small particles by 80-90% in this vehicle. A sedan would have even higher particle reductions.

Not bad. Twenty-five minutes of work and a total cost of about $45 for a cleaner and safer vehicle interior.