The United States Green Building Council (USGBC) has established a standard for indoor residential VOC levels. The spec is available here:

Total VOC Levels (TVOC) for residences should be below 500 ng/liter.That means if you collect a liter of indoor air and separate and weigh all the VOCs in the sample the total weight should be under 500 billionths of a gram. There are a number of labs that offer test kits to the public. I've used these two: Least Expensive. High Quality, recommended

Both testing labs use a version of Gas Chromatography/Mass Spectrometry called TO-17. All significant VOCs are totaled to determine the TVOC levels. Typically about 50 -400 different VOCs make up the total level. Home Air Check (prism labs) has tabulated a median of about 1200ng/liter for thousands of homes tested. This is about 2.2 times the maximum standard of 500ng/liters.

I find it curious that the major manufacturers of Photocatalytic Oxidizers (PCO) devices (MoleKule, RGF) never report VOC tests in homes. I think I know why. This technology works where different VOCs are limited and are at unusually high concentrations in special chambers. Not the environment we find in our homes. This characteristic has been noted in the scientific literature.

Here’s a quote from a recent overview of PCO technology in a scientific journal: - Highly recommended article!

“Currently most studies demonstrate their VOCs removal efficiency in a high concentration level (e.g., ppmv). More on-site demonstrations should be conducted in order to prove the efficiency in removal of indoor VOCs in realistic environments (e.g., residential and work spaces).”

Until this is demonstrated I have doubts about the effectiveness of these devices for VOC reduction in homes. Why else would the companies that do test always resort to very small test chambers with walls of stainless steel using just a few VOC at super high concentration. If these devices really worked the way the consumer want’s, in homes, these companies would test - in homes. Why spend tens of thousands of dollars for contrived setups when simple, cheap testing in real living spaces would resolve all doubt.