Ahead of Trump Visit, Church Makes Unproven Claim of Virus-Killing Technology

Church officials did not respond to requests for comment.

Mr. Bender said the technology, which would be installed in the ventilation system, generate positively and negatively charged oxygen ions. The ions then attach to particles in the air, adding electrical charge to the particles, causing them to clump together and fall out of the air. The ions could also react with the viruses to disable them.

Companies like CleanAir EXP base their claims on laboratory tests by outside firms but financed by the companies. A test of a CleanAir EXP device looked at a different type of virus in a test chamber about 900 cubic feet in volume — smaller than a box 10 feet on each side and tiny compared with the size of the church.

The test did not use the novel coronavirus that causes Covid-19 but a different virus that is often used as a stand-in for pathogens because it does not cause disease. “We do not, however, eliminate Covid-19 at this time,” the company said in a statement. “Our coronavirus surrogate testing results are significant for the future of clean air. We welcome the opportunity to collaborate with the CDC for additional laboratory testing and support the CDC’s guidelines on hygiene habits to prevent the spread of Covid-19.”

In the test, 99.9 percent of the virus was destroyed, but Mr. Bender said that level of effectiveness would “absolutely not” occur in a real-world setting like the church. However, the air purification system would “reduce the chances” for the transmission of disease, he said.

“The system could help reduce background levels of infectious virus in the air, but in a crowded situation such as a rally, it is most likely that any transmission that occurs is between people standing close to each other for prolonged periods,” said Linsey Marr, a professor of civil and environmental engineering at Virginia Tech.

William P. Bahnfleth, a professor of architectural engineering at Pennsylvania State University, who looked over the testing results, said, “Suffice it to say that, based on the evidence available, the scientific community is skeptical of performance claims for these devices.”

Anyone who registered for the event was required to sign a waiver.

“By attending this convention, you and any guest voluntarily assume all risks related to exposure to Covid-19 and agree not to hold Turning Point Action, their affiliates, Dream City Church, employees, agents, contractors, or volunteers liable for any illness or injury,” it said.