FAQ
I would not say that we are more focused on “smog reducing,” specifically, than “air purifying,” in general. Both are true and the customer can choose how to describe the benefit. Competing and related products in our industry have described themselves as “smog-eating” (e.g. Italcementi’s concrete) and we have also used that description. The photocatalytic reaction works to oxidize volatile organic compounds (VOCs) and to reduce NOx to nitrates. Both can independently be described as reducing air pollution.
U.S. EPA defines smog as a mixture of pollutants made up mostly of ground-level ozone. Are any of the following pollutants included in the vendor’s definition of “smog” (e.g. ground-level ozone, particulate matter, carbon monoxide, nitrogen dioxide, sulfur dioxide, and hazardous air pollutants)?
The definition of “smog” is not precise. In its common current usage, it is a combination of air pollutants, particulate matter, and even naturally occurring fog that creates a visible haze in the air. We specifically note our efficacy in reducing NOx and VOCs, which are accepted contributors to “smog.”
NOx and many VOCs are harmful air pollutants in their own right, so our claims of air purification are not dependent solely on their interaction to create ground level ozone. As it relates to being beneficial in the fight against climate change, NOx is by itself a criteria pollutant with an estimated GWP of 30-33 over a 20 year horizon. The creation of ozone is another mechanism by which NOx contributes to climate change. But yes, to the extent we discuss ozone reductions at all, it is through the elimination of the NOx and VOCs building blocks.
Yes, that is correct, though our research has focused on VOCs and NOx. The photocatalytic reaction has been shown by others to be effective against SOx (not only SO2 as you state in your question). While we are confident that our coating is acting similarly against SOx, we haven’t done independent research against that pollutant.
Again, I do not think that our claims should be limited to the ozone-creating interaction between NOx and VOCs. It does both and both are beneficial independent of ozone. We typically test for VOCs for indoor applications and NOx for outdoor applications because we believe that NOx is the primary driver concern outdoors. In indoor applications we have seen 60%+ reductions in VOCs levels, which is comparable to the percentage decreases we see for NOx on certain substrates. I would not choose to use the phrase “equally as efficient.” There are just too many variables for that assertion, and it could be more or less effective.
We do not make any claims about carbon dioxide. It is often used as a shortcut for a discussion about greenhouse gasses and climate change, but we do not modify CO2 molecules.
The amount of carbon in the air is the same. We do not emit any carbon, we modify it, which is a beneficial tradeoff either for human health or the planet. The tradeoff between a VOC and CO2 is going to have a net positive benefit. For instance, a molecule of methane has a global warming potential of 35. A molecule of CO2 has a GWP of 1. Oxidizing methane to four molecules of CO2 is therefore highly beneficial for the environment. VOCs, some of which are carcinogenic, are typically measured in parts per billion (ppb) whereas CO2 is measured in parts per million (ppm). Even in a polluted environment, the conversion of VOCs to CO2 is going to produce a minor change to the measured CO2 levels.
We normally describe the oxidation of NOx as the removal of harmful NOx from the air and the conversion into nitrates which can be consumed and recycled by plants. We have cited a research paper from the University of Bristol that states in its conclusion: “TiO2 is effective at converting nitrogen oxides to harmless nitrates …” “Photocatalytic oxidation of NOx gases using TiO2: a surface spectroscopic approach.” J.S. Dalton et al./Environmental Pollution 120 (2002) 415–422.