A Powerful, Affordable Solution for Cleaner Indoor Air

Indoor air quality plays a crucial role in overall health, especially for individuals sensitive to mold, allergens, wildfire smoke, or other airborne pollutants. While commercial air purifiers can be effective, they often come with a high price tag, making them inaccessible to many people.

The Corsi-Rosenthal (CR) Box is a DIY air purifier that offers a high-performance, low-cost alternative to expensive HEPA filtration systems. Developed by Dr. Richard Corsi and Jim Rosenthal, this simple yet effective design allows anyone to improve their indoor air quality for a fraction of the cost of commercial air purifiers.

How Does It Work?

A Corsi-Rosenthal Box uses a standard box fan to pull air through high-efficiency MERV 13 or MERV 14 filters, removing harmful airborne particles before they can be inhaled. This continuous filtration cycle rapidly improves indoor air quality, making it particularly useful in homes dealing with mold exposure, dust, and other contaminants.

Key Components of a Corsi-Rosenthal Box:

✔ MERV 13 or MERV 14 filters – Capture airborne contaminants, including mold spores, dust, bacteria, and fine particulates.

✔ 20-inch box fan – Pulls air through the filters, ensuring a continuous purification process.

✔ Duct tape and cardboard – Used to seal gaps, maintain airflow efficiency, and secure the structure.

By combining readily available, inexpensive materials, the CR Box provides an easy-to-build, highly effective air purification system for homes, classrooms, and workplaces.

Why a Corsi-Rosenthal Box is a Game-Changer

Unlike traditional air purifiers that require expensive replacement filters and proprietary technology, the Corsi-Rosenthal Box is designed for affordability and efficiency.

Key Benefits:

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

✔ Cost-Effective – A CR Box costs $50–$100, significantly less than a typical HEPA purifier, which can cost hundreds of dollars.

✔ Easy to Build – Requires no special tools or expertise—just a few simple materials.

✔ Customizable – Can be scaled up for larger spaces or used in multiple rooms.

✔ Sustainable – Reduces dependency on expensive air purifiers while providing long-term air quality improvements.

✔ Perfect for Mold Exposure – Provides immediate relief from airborne mold spores, reducing exposure while long-term remediation takes place.

Why MERV 14 Filters?

The Corsi-Rosenthal Box uses MERV 13 or MERV 14 filters, which are designed to capture:

✔ Mold spores and bacteria

✔ Fine dust and allergens

✔ Smoke particles from wildfires

✔ Other airborne pollutants that impact health

MERV 14 vs. HEPA – Understanding Efficiency

• MERV 14 filters capture at least 75% of particles at 0.3 microns, which includes many mold spores, fine dust, and bacteria.

• HEPA filters capture 99.97% of particles at 0.3 microns, making them the gold standard for air filtration.

• Multiple air passes through a MERV 14 CR Box can achieve similar overall filtration efficiency as HEPA, typically requiring 5-6 air exchanges through the filter to reach HEPA-equivalent performance.

While HEPA filters are superior in single-pass filtration, a properly placed and consistently running Corsi-Rosenthal Box provides ongoing filtration, ensuring that indoor air is continuously cleaned and improved over time.

A Smarter Approach to Clean Air

If you’re looking for an affordable, high-performance air purification solution, the Corsi-Rosenthal Box is one of the best DIY options available today. Whether you’re dealing with mold exposure, allergies, or general air quality concerns, this easy-to-build filtration system offers a powerful, budget-friendly way to breathe cleaner air.

In the next section, we’ll walk you through the step-by-step process to build your own Corsi-Rosenthal Box and maximize its effectiveness in your home.