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With growing evidence that airborne virus particles are the main cause of Covid-19 infection, scientists have developed air-purifying innovations.

By Abigail Klein Leichman, ISRAEL21c

Remember when pollution was our worst respiratory worry? Now, scientists say airborne virus particles may be the main cause of Covid-19 infections.

In the face of new evidence, the World Health Organization has changed its tune about the virus not being transmitted through air.

“WHO, together with the scientific community, has been actively discussing and evaluating whether SARS-CoV-2 may also spread through aerosols … particularly in indoor settings with poor ventilation,” the agency announced July 9.

Simply improving ventilation isn’t always possible or adequate. And although a new American study found that covering the nose and mouth can decrease risk of SARS CoV-2 infection by 65 percent, many people resist wearing facemasks.

The ultimate answer could be one or more of these Israeli high-tech solutions to cleanse indoor air from dangerous pathogens.


This device sterilizes indoor air by slowly releasing chlorine dioxide (ClO₂) in tiny amounts– far below the approved level of ClO₂indrinking water.

“Chlorine dioxide is powerful against viruses and other types of germs because only a very small amount deactivates the virus as soon as it gets on one of its outer spikes. It doesn’t need to go into the core of the virus to kill it,” explains ProtectAir cofounder Tsvi Dahan.

“The efficiency is therefore very high. And it’s safe because it doesn’t go into the body. It stops on the spike.”

The small device can be mounted on a wall or placed on a surface and doesn’t need electricity, Wi-Fi or batteries. “For a very big space you might put four or five units,” Dahan says.

It comes with a sachet of granules to place inside. Refills are needed about every four weeks. An optional upgrade is a gel that’s a little more powerful for a large area and lasts a longer time.

“Opening the package activates the granules or the gel. By nature, chlorine dioxide vaporizes and oxidizes quickly. But ProtectAir’s formulation allows it to be released gradually and uniformly.”

ProtectAir was tested for efficacy against SARS-CoV-2 at Israel’s Amnilabs and has undergone safety testing in Israel and overseas.

“Two hours after you put it in the room, the air is sterilized and continues to be sterilized for three to four weeks. You don’t need to do anything to activate it if a person sneezes or coughs.”

The system was invented by Tsvi’s brother, Meir Dahan, who was a specialist in machine and water purification for 15 years at Soreq Nuclear Research Center.

“This is where he got to know ClO₂. Most companies use it in liquid form to purify water, but he knew it could purify air also. When news about the coronavirus began in December, Meir thought about how to use it differently. He worked with one of the producers to make it release into the air consistently, 24/7, for a period of a month or so.”

Sales are beginning in Israel. “We are speaking with government ministries to get ProtectAir units in public transportation, schools, and government offices,” says Dahan. “We are also speaking with an Israeli company about marketing it globally.”


Israeli startup Aura Air has completed two phases of a pilot at Sheba Medical Center to check the efficacy of its air filtration and disinfection system.

Aura Air’s device senses contaminants and filters out tiny particles of bacteria, viruses, pollen, mold, fungi and other particulates.

The system uses a carbon- and copper-infused “Ray” filter, a HEPA (high efficiency particulate air) filter, a pre-filter and ultraviolet UVC LEDs. It also generates positive and negative ions to freshen indoor air.

In previous lab experiments, the system demonstrated an average of 99 percent effectiveness against influenza viruses.

“We started the collaborative work with Sheba in an effort to reduce contaminants in the hospital, and then the coronavirus arrived,” said Roy Friedberg, vice president of Aura Air. “Now we are focusing on purifying and disinfecting the air from severe viruses, including the coronavirus.”

Aura Air was tested in a hotel, a conference room in a commercial building and a residential apartment in the United States that showed significant improvements in air quality.

The company is conducting other tests in collaboration with Israeli strategic partner Beth-El Industries, which makes advanced air filtration systems for the civilian and military sectors worldwide.

Aura Air has received a $1.5 million grant from the Israel Innovation Authority and expects EU funding, said Friedberg. “The goal is to target solutions for closed-space infections in general, and the coronavirus in particular.”

Ultraviolet-C Light

Ultraviolet C (UVC) light, a known disinfectant, could be a “particularly efficient, easily deployable, and economically affordable” way to inactivate the coronavirus in indoor air, says a team of international scientists including Prof. Ido Kaminer of the Technion-Israel Institute of Technology.

The scientists suggest a global capital investment in UVC sources — such as fluorescent lamps, microcavity plasmas and LEDs on the inside of the ventilation systems of buildings and in shared indoor spaces – would quickly deactivate airborne and surface-deposited SARS-CoV-2 viruses.

“The Covid-19 outbreak, caused by the SARS-CoV-2 virus, is posing an extraordinary challenge that requires swift worldwide action for the massive deployment of affordable and ready-to-apply measures to drastically reduce its transmission probabilities in indoor spaces,” their report said.

“Doing so will allow for the eventual return to conventional activities such as working at the office, going to school, or even attending entertainment events.”

Sterilizing Air Filters

A new type of air-filter that self-sterilizes and decontaminates is being developed at Ben-Gurion University of the Negev Israel based on water filtration technologies.

The new nanotechnology is derived from laser-induced graphene (LIG) water filters that eliminate viruses and bacteria in water.

This new concept, re-engineered for air-filtration, could be used in heating, ventilation and air-conditioning (HVAC) systems or integrated into facemasks for a self-sterilizing effect.

LIG is resistant to bacteria and actively kills microbes and viruses using a low-level electric current from a power source. The researchers explain it’s a two-fold protective system.

“The bacterial-resistant graphene surface protects against microorganisms so they can’t multiply, while the microbes trapped in the filter are eliminated by the electric current,” says inventor Chris Arnusch, senior lecturer and researcher at BGU’s Zuckerberg Institute for Water Research, part of the Jacob Blaustein Institutes for Desert Research.

“Thus, an LIG air filter has the potential to be combined with state-of-the-art air filtration such as HEPA filters. The filters could add an active layer of protection, as well as prolong the lifetime of the expensive HEPA technology. As a result, hospitals, cars, buildings and public transport could all become safer spaces,” said Arnusch.

Supported by the BGU Coronavirus Task Force, Arnusch and immunology experts are testing the air filters against viruses.



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