Silicon Valley air purifier startup Molekule was born out of an idea Dr. Yogi Goswami had back in the ’90s using photo-voltaic technology to kill air pollutants. His son, a young boy at the time, suffered from severe allergies and Dr. Goswami wanted to build something those like him could use in their home to clear the air. But the sleekly designed Molekule took a bit of a blow last fall when Wirecutter called it “the worst air purifier we’ve ever tested.”

Molekule has since told TechCrunch comparing its PECO technology to the more common HEPA air filter technology is like comparing apples to oranges. “Up until now, everything has been air filtration, not real air purification,” co-founder and CEO of the company Jaya Rao told TechCrunch.

To disprove the naysayers, Molekule sent off its tech for testing at the Berkeley Lab, which concluded no measurable amount of VOC’s or ozone were emitted; Molekule effectively removed harmful chemicals in the air, like toluene, limonene, formaldehyde, as well as ozone, and that “no secondary byproducts were observed when the air cleaner was operated in the presence of a challenge VOC mixture.”

Compare that to Wirecutter’s own assessment that, “on its auto setting, which is its medium setting, the Molekule reduced 0.3-micron particulates by (in the best case) only 26.4 percent over the course of half an hour. Compare that with the 87.6 percent reduction the Coway Mighty achieved on its medium setting.” TechCrunch reached out to Wirecutter and was told it still stands by its findings and does not recommend consumers purchase a Molekule.

It should be noted Consumer Reports also tested the Molekule device and it, too, did not recommend a purchase as the unit was not “proficient at catching larger airborne particles.” However, Molekule demonstrated to other news outlets at its own facilities that the photochemical reaction in its units did break down contaminants and kill mold spores.

“To test PECO technology you actually need really sophisticated equipment,” Rao said. “Boiling it down to really simple factors is not enough because air is made up of many tiny but toxic things. These are air-borne chemicals nanometers in size, which Wirecutter admittedly did not test at all for.”

Wirecutter’s Tim Heffernan disputes Molekule’s claims of superiority in the category, however. “Now they are comparing apples to oranges,” he told TechCrunch. “The claims about destroying bacteria and viruses, for example, HEPA filters capture them and they capture them permanently.”

So how’s a consumer to know what’s right? First, take into account Molekule commissioned the Berkeley Lab for their independent testing and that Wirecutter and Consumer reports ran their own independent testing. However, it might boil down to understanding the premise of the technology. HEPA filters came out of the Manhattan Project in the 1940s, when scientists needed to develop a filter suitable for removing radioactive materials from the air. It works by capturing and filtering out harmful particles, viruses and mold. However, PECO, the technology in a Molekule unit, uses the science of light to kill mold and bacteria and break down harmful particulates in the air.

Regardless of whether you want an air purifier that captures particulates or breaks them down, Molekule has continued to move forward. The company has since launched a mini unit meant for smaller rooms and started to grow business verticals outside of the direct-to-consumer model, forging partnerships with hotels and hospitals.

It also just announced a raise of $58 million in Series C funding, bringing just over $91 million to its coffers. Rao tells TechCrunch the raise was unexpected, but came out of chats with Samantha Wang from RPS Ventures, which led the round.

“We feel confident in Molekule’s PECO technology, and have taken an extensive look at the science behind it. It is not only backed by decades of academic research, it has also gone through the peer-reviewed process numerous times, and has been tested and validated by third-party scientists and laboratories across the country,” Wang told TechCrunch.

Other participation in the round included Founder’s Circle Capital and Inventec Appliances Corp (IAC). Existing investors Foundry Group, Crosslink Capital, Uncork Capital and TransLink Capital also participated in the financing.

Molekule also tells TechCrunch it has seen a healthy growth trajectory in the past year, despite the negative press. According to the company, Molekule has seen a 3x increase in year over year filter subscription revenue since launch, and its repeat customer growth sits at about 200%.

It’s a well-designed, though pricier air purification machine with an interesting future in the commercial space, particularly in hospitals, schools, commercial manufacturing and hotels, as Wang points out.

As long as the tech truly makes the air better.