PHOENIX — President Trump is visiting one of the nation’s biggest megachurches on Tuesday to speak to thousands of Arizona college students gathering to support his re-election. With coronavirus cases sharply increasing in the state, some public health experts say the gathering is a potential disaster.
But the church hosting the event offered a possible solution on Sunday: A system installed in the building’s ventilation system cleans the air and “kills 99.9 percent of Covid within 10 minutes.”
The technology, the church’s pastor said in a Facebook post that has since been removed, was developed by a local company whose owners also happened to be members of the church.
“So when you come into our auditorium, 99 percent of Covid is gone, killed, if it was there in the first place” Luke Barnett, a pastor of Dream City Church, said in the video. “You can know when you come here, you’ll be safe and protected. Thank God for great technology and thank God for being proactive.”
Even as the state is seeing some of the steepest increases in cases and deaths in the country, thousands of residents have packed bars and restaurants in recent weeks, trying to escape both heat and boredom. Until last week, Republican Gov. Doug Ducey prevented Democratic mayors in the state from requiring face masks. After calls to restrict or cancel the event, Mr. Ducey told reporters last week: “We’re going to protect people’s rights to assemble in an election year,” and he is expected to attend.
Mayor Kate Gallego of Phoenix, a Democrat, repeatedly criticized the event, saying in a statement on Monday that “It does not abide by C.D.C. guidelines during Covid-19.”
“Public health is a group effort, not a partisan issue,” she added. “It requires the participation of every resident and every level of government.”
As the event began Tuesday, photos inside the church showed the crowd shoulder to shoulder, with very few appearing to wear masks.
Tuesday’s event is sponsored by Students for Trump, a group affiliated with Turning Point USA, a pro-Trump group backed by the financier Charlie Kirk. Organizers of the event told local reporters that they expected roughly 3,000 attendees to comply with the city’s new mask ordinance.
Using charged ions to remove airborne pollutants is not new, and such a system could help cleanse the church’s air, but certainly without the rapidity claimed, and it would not guarantee safety, experts said.
“The claims seem suspicious on several counts, but they don’t provide enough information to decipher what they are really doing,” said Jose L. Jimenez, a professor of chemistry and biochemistry at the University of Colorado at Boulder.
A phone call to Jerry McGuire, president of CleanAir EXP, the company behind the technology, was not returned. Church officials did not respond to requests for comment.
These systems, which would be installed in the ducts of the ventilation system, typically use a strong electric charge to strip electrons from atoms, turning them into charged ions. The ions then attach to particles in the air, adding electrical charge to the particles. The charged particles are then attracted to a surface with the opposite electrical charge. Once pulled there, they are stuck to the surface, removed from the air. “This technology is well-established for removing aerosols from an air stream,” said Linsey Marr, a professor of civil and environmental engineering at Virginia Tech.
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.
In a more realistic setting, it would take some time before the air recirculated through the ventilation system, and someone near an infected person could easily be exposed to the virus before the air had a chance to be recirculated and cleaned.
“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,” Dr. Marr said.
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.