Why CADR rating system is not that efficient as you may have thought. Here we debunk the myths.

Why CADR rating system is not that efficient as you may have thought. Here we debunk the myths.


BRID Air Purifier technology is not based on particle capture, but instead based on photocatalysis-induced chemical transformation. There’s a fundamental difference between simply trapping particles and volatile compounds and rendering them harmless. In contrast to BRID purifiers, purifier manufacturers often rely on commercial indexes which are only suitable for standard or basic technologies.

In this article, we will endeavor to remove any doubts regarding BRID. We will also attempt to understand the differences between a variety of currently available air purification technologies as well as understanding which indexes are best for interpreting the quality of one technology over another. 

Physical filters and ionizers are intended to treat particles, and current standards are calibrated to or based on said technologies. To this day, there is no official proof which determines that filters and ionizers have the ability to reduce or remove gas pollution in the air. BRID’s technology was analyzed by a number of laboratories. The analysis protocols used, strictly observed scientific theory (empirical analysis). Please note that there are no directives for European protocols regarding gases in indoor/domestic environments. Some of the indexes used are Clean Air Delivery Rate (CADR) and Minimum Efficiency Reporting Value (MERV). 


Cooking emission is one of the main sources for ambient volatile organic compounds.

CADR Rating

Developed by AHAM (Association of Producers of Domestic Appliances) in the early 80s, this method outlines a method used to measure the output speed of filtered air. It also measures the ability of a device to reduce smoke, dust and pollen particles in a room. Clean Air Delivery Rate was designed when air purifiers followed precisely one principle: blocking polluting particles which moved towards a filter by fan suction. Many new filtering technologies have been developed since AHAM introduced their standard, so we should distinguish the difference between filters which simply block particles and those which destroy them. While adequate for the time it was developed, it has a few shortcomings:
CADR only applies to particulate pollution like smoke, dust, and pollen, ignoring gases completely. Smoke particles, dust and pollen aren't the only pollutants found in a domestic environment. Many other substances exist which pollute the air such as carbon monoxide, volatile organic compounds (VOCs), ozone, sulfur oxide, nitrogen oxide and other such substances which, since they're not particles, are ignored by the CADR standards.
It only demonstrates the ability of a filter to block particles but provides no information regarding how effective it is at destroying pollutants; therefore it is unable to measure filtration quality.
The efficiency of the filter is calculated solely based on a single passage of air through the filter.
A filter which blocks particles can retain bacteria and mold. If allowed to grow on the filter, these pollutants can diffuse in the air, putting human health at risk.
Even if the physical filters can stop large particles of pollen, smaller particles which cause allergies can often pass freely through these filters and be diffused in the breathable air around the filter.
As should be obvious from the name, this filtration measurement depends on the airflow of the purifier. A filter capable of generic filtration slows the airflow as it passes through, reducing the rate at which air flows through the filter.
It uses a 28.5 cubic meter room in which measurements are taken as the filter is in operation. This does not take into account particles that may spontaneously decay later.
It only measures particles which are left in the air, not ones which have been trapped.

The MERV Rating

For clean rooms, hospitals or airplanes which use high-efficiency HEPA filters, CADR is not ideal. These environments instead use Minimum Efficiency Reporting Value, or MERV. MERV was created in 1987 by AMSEH (American Society of Engineers of Heating, refrigeration and air-conditioning), to evaluate the efficiency air purification systems. It measures the elimination of particles down to 0.3 micrometers (viruses, bacteria, smoke, etc.) but not gaseous substances. The scale is based on the ability of the filter to retain particles ranging from 0.3 to 10 micrometers. The MERV index goes from 1 to 16 micrometers, 16 meaning that 95% of particles are captured in a designated space. A high-efficiency HEPA filter is very dense and as a result the airflow coming from the system is dramatically reduced.

Unlike other filters on the market, BRID doesn’t physically trap pollutants but breaks them down into harmless particles. This allows BRID to get rid of harmful substances regardless of their size.  

What about BRID?

Some scientific publications have described protocols for the effectiveness of reducing gases like VOCs, ozone, and the like. AFNOR, the French accreditation entity, developed one which defines the effectiveness of a given method's air purification. The BRID purifier’s technology was tested by independent laboratories in a very similar manner to these protocols. A plexiglass box measuring 1 cubic meter in volume was used. This box was polluted with molecules present in domestic and or residential environments. The choice regarding the initial concentration of various substances was taken from regulatory requirements of exposure limits and instrumental detection limits. From the data acquired a CADR can be determined. Every substance has a specific air delivery rate, and for that reason, a reference similar to the other systems that measure the neutralization or removal of gases should be used.



We wanted to share this knowledge with you as many customers guide their choice of air purifier by inquiring about the CADR rating system. Actually, it is not as thorough as system as many believe it to be. Information is power and by knowing this you will be able to make a conscious informed decision as to why BRID is actually better.

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