What Are Air Purifying Paints (And How Do They Work)

Air purifying paint is a new type of paint that claims it can absorb and/or break down volatile organic compounds (VOCs) in the ambient air of the home.

These paints can contain up to 10% sorbent material, like zeolite. This certainly reduces the odor of the paint while wet. Once the paint is cured, zeolite can then release those VOCs (if the ambient VOC levels are low enough) and reabsorb future VOCs.

Many of the air-purifying paints on the market also claim to break down VOCs using photocatalytic oxidation (PCO).

Photocatalytic oxidation

Titanium dioxide, the white pigment and filler in all paints, can interact with UV light and produce hydroxyl radicals which break down VOCs. It’s the same process used in photocatalytic oxidation air (PCO) purifiers like Molekule.

Sherwin-Williams

Sherwin-Williams Super Paint with Air Purifying Technology is a zero-VOC acrylic paint that they claim can break down unwanted household odors and reduce VOCs in the home.

Based on a patent held by the company, it could be that their air-purifying paints contain sodium bicarbonate, zeolite, activated carbon, and/or cyclodextrin as odor-absorbing agents. The patent also describes possible odor-neutralizing agents like undecylenic acid, undecylenate silicone esters, chloramine-T, and zinc ricinoleate.

They mention that the paint can contain nano-titanium dioxide, zinc oxide, or anatase titanium dioxide, which are capable of degrading odors in the presence of UV light.

This PCO process can work in theory with some indirect sunlight or light through a window but this PCO process works best when the sun hits titanium dioxide directly, unobstructed, according to Dr. Steven S.C. Chuang who holds a Ph.D. in Chemical Engineering and has published papers on photocatalytic processes.

They also list a possible fragrance added to the paint.

As for the other chemicals listed in the Sherwin-Williams patent, I didn’t find confirmation from them or any other paint company that they use these, though it certainly is possible that they could be used by Sherwin-Williams or others:

• Undecylenic acid is an odor-neutralizing agent that reduces the vaporization of malsensory agents.
• Cyclodextrin interacts with odor-causing molecules and can encapsulate them within its cavity.
• Chloramine-T sodium, another odor-neutralizing agent, can potentially form chemical bonds with volatile compounds, altering their chemical structure and reducing their odor intensity.
• Zinc ricinoleate, the last odor-neutralizing agent mentioned in the Sherwin-Williams patent, acts by forming complexes with odor molecules, effectively trapping and reducing their volatility.

ECOS Paints

ECOS Paint also makes an Air Purifying Paint and Air Purifying Primer. They claim that the paint “absorbs and neutralizes chemicals, pollutants, and VOCs for improved indoor air quality.”

They provide full transparency in ingredients: zeolite is the odor-absorbing agent. The paint also contains titanium dioxide which could be classified as an odor-degrading agent, and vanillin, a fragrance for odor masking.

The titanium dioxide in ECOS Air Purifying Paint is no different from the titanium dioxide in their regular paint, says Emma Pugliares, a rep for the company.

Auro

Auro Airfresh Wall Paint also claims that their paint has a photocatalytic effect due to titanium dioxide. This brand is the only one that mentions that adding colorants will decrease the photocatalytic effect. They advise adding no more than 5% pigment so as not to decrease the amount of titanium dioxide too much.

They do say that the titanium dioxide is a “special fine structure” but it’s not clear whether this means nano or if it is different from the titanium dioxide in regular paint (and a rep for the company did not know).

They did provide two small case studies via email. In the first one, they used a UV light which certainly would increase the photocatalytic effect, though the case study did not precisely identify the type of lightbulb used.

The second case study showed that the paint reduced formaldehyde levels in the chamber by 90% in one hour, while the sample plate “painted with a regular coating” (we can assume this is the company’s regular wall paint, though it’s not 100% clear) reduced formaldehyde in the chamber by 74% in an hour. They do not say what kind of light bulb was used.

This difference between their AirFresh paint and regular wall paint could have to do with the amount of titanium dioxide in the paint or the type of titanium dioxide.

BONA

I also talked to John Schierlmann, Director Of Research And Development at BONA, and a patent holder for air purification coatings.

He conducted the case study described here where they tested coatings with titanium dioxide, versus a control that had no catalyst at all.

T8 LED lights were used as the energy source. They were able to prove a reduction of formaldehyde and methyl mercaptan in a controlled chamber. They note that it is more challenging to demonstrate this in a room in a house.

In a private correspondence, Mr. Schierlmann explained that there are some scientists that suggest regular titanium dioxide has some amount of photocatalytic effect. For their coatings used in this experiment (which did not come to market in North America) he said they were using a “functionalized mixed metal oxide (titanium dioxide-nano particles that is fused onto diatomaceous earth)”. And that the mean particle size was around 0.25 microns (out of the nano particle range). So this is different than your regular titanium dioxide paint pigment. (And this was for clear coatings).

What’s different in a regular house compared to these small experiments? Most notably the amount of light- most rooms do not get direct, unobstructed UV light from the sun. Also: air exchange, air tightness, the level and source of VOCs emitted, and the natural degradation of formaldehyde that happens in the presence of background levels of ozone.

It should also be noted that PCO air purifiers can often raise the VOC levels since they often create intermediary byproducts when breaking down formaldehyde.

Premier Clean

I looked at a couple of other brands, Premier Clean Line which is the in-house brand by Canadian Tire spent. They claim their Premier Clean line “purifies air by trapping airborne chemicals”. There’s no information on what’s in it.

Cair

Cair is another air-purifying paint that works based on a catalyst present in the formula, they claim that their formulation is also able to function even without any light. I don’t know how that is possible.