What Are Cold Catalyst Air Filters?

Cold catalyst filters are a type of filter used in air purifier that transform VOCs, formaldehyde, benzene and other harmful gases into less-toxic pollutants.

They are similar to a catalytic converter in the exhaust pipe of a car or other road vehicle, and typically use a metal oxide catalyst that creates an oxidation and a reduction reaction with the harmful gases.


cold catalyst air purifier filter like catalytic converter car


Which Air Purifiers Currently Use Cold Catalysts?

The Molekule air purifier uses a form of cold catalyst filter called Photocatalytic oxidation (PCO) technology.

Review: Is the Molekule Air Purifier As Good as The Claims? 

A report by Consumer Reports found the air purifier to be one of the worst they’d tested, and the National Advertising Division in the US found that there were multiple misleading claims relating to the effectiveness of the PCO technology at ‘destroying’ VOCs and other harmful gases.

What Does the US EPA Say About PCO?

The United States Environment Protection Agency states that PCO technology’s use in the home is “limited because currently available PCO Gases catalysts are ineffective in destroying gaseous pollutants from indoor air”. They go on to state that “Some PCO cleaners fail to destroy pollutants completely and instead produce new indoor pollutants that may cause irritation of the eyes, throat, and nose”.


Are Cold Catalysts an Alternative to Activated Carbon?

Based on reports from both the the US EPA, Consumer Reports and the National Advertising Commission, cold catalyst PCO technology has not yet been proven effective for use in home or school environments. What’s more, UV lights used in PCO technologies can also produce harmful pollutants such as ozone.

Activated carbon filters have been in use in industry and homes since the beginning of the 20th century. While activated carbon does not destroy harmful gases – it captures them – it has been proven effective at removing gases such as formaldehyde and benzene from the air.

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