PECO air purifiers manufacturers promise to not only capture air pollutants, but also destroy them. Sounds great right? Not so fast.

After taking a closer look at how PECO technology works and what it does, we can understand why this form of air cleaning is a simple case of “too good to be true.”

Advertisements often purport that PECO technology is new, but it really isn’t. PECO, short for photoelectrochemical oxidation, is a type of PCO or photocatalytic oxidation, and it has been used in air cleaning for years.

Current versions of air purifiers using PECO technology combine a mesh HEPA filter coated in a catalyst that reacts with UV light to oxidize gas pollutants. But there are many other elements besides the filter that go into constructing an effective and efficient air purifier.

When choosing an air purifier, there are two factors that are paramount to determining the total system efficiency:

• Airflow (with filters installed)
• Filtration efficiency (both short and long-term efficiency)

So that: airflow x filtration efficiency = total system efficiency.

Read on to see why PECO air cleaning technology can’t deliver on promises of creating truly pure air – and how HyperHEPA filtration can.

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Airflow

Airflow is essential for moving air through an air purifier to clean the air. However, sufficient contact time is imperative to PECO technology and sufficient contact time is counterproductive to high airflow. In other words, in order for PECO technology to work, lower airflow is required. As such, air purifier manufacturers using PECO technology do not state the units’ airflow in terms of cfm or m3/h, as it would be appropriate for an air purifier. Instead, there are claims that PECO air purifiers are able to “completely replace the air in a 600 square foot room (an average living room) once an hour”. Even if that claim is true, the unit would only produce around 145 m3/h at maximum fan speed. That is a third of the power found in an IQAir HealthPro Plus air purifier. In other words, the PECO technology is overall much less efficient and effective. In fact, it would take at least seven popular PECO technology air purifiers to equal the air cleaning performance of one HealthPro Plus with HyperHEPA technology.

To further hammer home the point, air purifiers with PECO technology were found to be ineffective in improving the air quality in schools in New York City, resulting in an increase in COVID infections. (1)

Efficiency

There is a reason efficiency data for PECO air purifiers is not clearly stated, even in product tech specs. This is most likely because there is little or no scientific evidence proving the efficiency.

Without efficiency data, there is no way to compare the actual filtration efficiency of an air purifier using PECO technology to other air purifiers. Blanket statements claiming “PECO technology is able to destroy pollutants 1000 times smaller than traditional HEPA filters” are baseless (proof is referenced below).

It’s also important to note that “destroying” pollutants is not the same as “filtering” them. Filtering pollutants removes them from the air and prevents them from entering the breathing zone. However, destroying pollutants refers to partially or fully inactivating, which doesn’t necessarily remove the pollutant from the air or breathing zone.

CADR - Short-term efficiency only

Clean Air Delivery Rate (CADR) is the Association of Home Appliance Manufacturer’s standard for measuring the volume of filtered air that a given air cleaner can achieve. (2) Not all air cleaners have a CADR number because it’s not mandated.

CADR doesn’t tell the whole-story. However, CADR provides a good way to make a short-term comparison of air purifiers. However, many air purifier manufacturers design their products specifically for the test and ultimately have poor long-term performance. In fact, many air purifiers lose 50-75% of their CADR ratings in between filter changes. The HealthPro Series is designed to lose no more than 10% of its particulate purifying power in between filter changes.

But for those that are rated, their CADR numbers allow customers one way to directly compare air purifiers. Each rated model receives scores for smoke, dust, and pollen, which are meant to represent three different particle sizes: smoke being the smallest and pollen the largest.

As valuable as CADR ratings are for head-to-head comparisons of air purifiers, they are not the best indicator of a product’s performance as they are basically just measuring how quickly a specific purifier cleans the air (and not even how clean that air is on the other side of the process).

But there is a rating that is more valuable when it comes to judging a product’s performance.

CCM - Long-term efficiency

Cumulate clean mass (CCM) is a measurement that points to how much particulate matter and formaldehyde a filter can capture over time before it starts to lose its efficiency. For particulate matter, the ratings start at P1 and go up to P4, the best mark. Similarly, when measuring a filter’s efficiency for capturing formaldehyde from the air, the rating is between F1 and F4.

So essentially, an air purifier’s long-term performance is best specified through its CCM numbers.

The China Household Electrical Appliances Association ranked IQAir’s HealthPro series among the top in its “List of Outstanding Air Purifiers Regarding Particulate CCM,” and acknowledged that it is the only product whose particulate CCM rating is tested above 1 million mg - more than 8 thousand percent above the base P4 level.

Scientific Evidence of Effectiveness

IQAir’s HyperHEPA filtration technology is proven to remove 99.5% of all particles down to 0.003 microns.

Some products’ “scientific evidence” of their performances are not based on the actual air cleaner being tested in laboratory conditions. To prove effectiveness, an air purifier should be tested as it would be used in a real-life setting. Meaning, the air purifier should be tested in a room that rivals a typical bedroom or living room, with pollutants commonly found in these settings. Air purifiers using PECO technology do not currently provide any scientific testing meeting these parameters.

The Takeaway

Beware of any air purifier that tries to tell you that it is using a “revolutionary new technology that completely destroys all indoor pollutants”. If it sounds too good to be true... it is too good to be true. In air cleaning, there are no silver bullets.

What’s more confusing is that some of these air purifiers are cleared as a class II medical device by the FDA, which gives confusing efficacy to these lower performing air purifiers. It’s important to note that the FDA does not evaluate air purifiers within the context of comparative performance of air purifiers. Instead, the FDA only evaluates an air purifier’s ability to meet its performance claims. However, these manufacturers have a way with words that makes it difficult for consumers to navigate overall air purifier performance.

A case in point: in 2020 the National Advertising Review Board (NARB), found that one manufacturer made these unsubstantiated claims:

• PECO technology is comparatively better than air purifiers with HEPA filters
• PECO technology removes, destroys, or completely eliminates all pollutants in a room
• PECO technology can destroy a million allergens in 4 minutes

NARB also objected to statements of allergy and asthma relief, and disputed that certain tests were conducted by an independent source as the company maintained. The review board however decided that the manufacturer did support its assertions of this product being able to address bioaerosol and VOC pollution. (3)