What is a Corsi-Rosenthal Box

An Affordable, High-Performance Air Filtration Solution

The Corsi-Rosenthal (CR) Box is a DIY air purifier designed to improve indoor air quality by removing airborne contaminants such as mold spores, dust, allergens, wildfire smoke, and fine particulate matter. Unlike expensive commercial air purifiers, the CR Box is a low-cost, highly effective alternative that can be built with simple materials found at most hardware stores.

Developed by Dr. Richard Corsi and Jim Rosenthal, this design has been tested in real-world conditions and shown to perform as well as, or even better than, many commercially available HEPA air purifiers in removing harmful airborne particles.

How It Works

A Corsi-Rosenthal Box operates by using a standard box fan to pull air through high-efficiency HVAC filters, capturing airborne contaminants before they can be inhaled. This creates a continuous cycle of filtration, rapidly improving indoor air quality.

Key Components of a Corsi-Rosenthal Box:

✔ MERV 13 or MERV 14 filters – These high-efficiency filters are arranged in a cube or pyramid shape to maximize airflow and filtration efficiency.

✔ A 20-inch box fan – Positioned on top of the unit, the fan pulls air through the filters, removing harmful particles.

✔ Duct tape and cardboard – Used to seal gaps and direct airflow, ensuring maximum filtration effectiveness.

The design is simple, yet highly effective, making it accessible for anyone looking to improve indoor air quality without the high cost of commercial air purifiers.

Why MERV 14 Filters?

While standard air purifiers use HEPA filters, the CR Box uses MERV 13 or MERV 14 filters, which are specifically designed to trap small particles, including:

✔ Mold spores

✔ Fine dust and allergens

✔ Bacteria and airborne pollutants

✔ Smoke particles from wildfires

MERV 14 filters capture even smaller particles than MERV 13, making them a preferred choice for those dealing with mold exposure and indoor air quality concerns.

Why Choose a Corsi-Rosenthal Box?

✔ Highly Effective – Captures up to 90% of airborne mold spores and fine particulates.

✔ Affordable – Costs between $50 and $100, significantly less than commercial HEPA purifiers.

✔ Easy to Build – Requires no special tools or technical skills.

✔ Customizable – Can be adjusted in size or modified for specific filtration needs.

✔ Sustainable – Extends the life of HVAC systems by reducing airborne contaminants before they reach return vents.

A CR Box is an ideal solution for individuals looking to quickly and affordably improve air quality, especially when dealing with mold exposure, allergies, or poor ventilation.