Researchers at the University of Houston teamed up with the University of Texas and Medistar Corporation to create a COVID-19-killing heated air disinfection system. The specialized air filter can be used to “catch and kill” the virus that causes COVID-19, SARS-CoV-2. According to a paper published in the Material Today Physics journal, the filter is made out of nickel-based foam and is heated to 392 degrees Fahrenheit (200 degrees Celsius). It operates as part of a heated air disinfection system that has been shown to effectively remove and kill 99.8 percent of SARS-CoV-2 airborne particles.
According to Doctor Zhifend Ren, co-corresponding author of the published paper and University of Houston’s MD Anderson Chair Professor of Physics, the future plan for the disinfection system includes installing the specialized filter in air filtration systems, such as air conditioners, HVAC units, and heating ventilators, in both public and private places, including schools, hospitals, airplanes, hotels, restaurants, cruise ships, offices, and homes. The new air filtration system will significantly reduce the exposure risk of catching COVID-19 because research shows that the virus can remain airborne for as long as three hours.
Doctor Ren stated that the filter could be useful in office buildings, schools, cruise ships, airports, and airplanes to stop the spread of the coronavirus. He stated that its ability to control the spread of the virus is very useful for public health. Medistar Corporation, which is a real estate firm that collaborated with the researchers, also pictures the creation of a portable desk-top model that can filter air surrounding an employee’s work space to minimize the risk of catching the virus on the job.
Medistar is responsible for the idea that inspired the creation of the filter, which was intended to help make the reopening of businesses safer, especially in spaces with air conditioning. Researchers hope that their new creation will help make the workplace safer for being with higher risks of exposure to the virus, such as those who work in hospitals, schools, airplanes or airports, buses, subways, and doctor’s offices. People who work in these areas will be given higher priority as the device starts to roll out in phases.
According to Doctor Garret K. Peel, Medistar’s Executive Vice President and Managing Director, the air filter will be compatible with MERV-11 and 13 variations of the HVAC system as it meets criteria and FDA guidance for 510-K applications, which issues its safety during the current pandemic. Doctor Peel stated that the manufacturing partners are working diligently to create the filters and disperse them to high-risk states, such as Florida, Arizona, and Texas. They hope to have these air filters ready for use within 60 days. Doctor Peel also stated that both the larger scale units and the smaller, portable devices would be able to clean the air 12 times each hour with significant results. He continued by saying that existing HVAC systems have the ability to be easily retrofitted with the air filter that is proven to catch and kill SARS-CoV-2 immediately. He stated that other systems, such as the HEPA, only catch the virus but do not kill it. The new filter that researchers are working on can not only catch it, but kill it, too.
While the temperatures that the air filter uses for its heating system reach 392 degrees Fahrenheit (200 degrees Celsius), it does not create a fire hazard because it pulsates. Doctor Peel stated that the filter is made of a high performance metal and has been shown not to affect surrounding air. The air filter is located in a fire retardant and resistant structure that is designed to hold temperatures that exceed 1,000 degrees Fahrenheit. This is important because research shows that higher temperatures are the key to killing the virus.
An air filtration system alone is not enough to prevent the spread of the coronavirus as it easily transfers from person-to-person. There also needs to be a “killing” component located within the trapping device to stop the exposure in its tracks. The researchers stated that the majority of viruses cannot survive temperatures that reach and exceed 158 degrees Fahrenheit (70 degrees Celsius). They concluded that once the temperature in the air filter reaches 158 degrees Fahrenheit, it takes about five minutes to kill the virus.
If the temperature in the nickel-based ventilation system is set as high as 250 degrees Celsius, then any circulating COVID-19 particles will be killed almost immediately, according to researchers. When the team tested the system with various temperatures, they found that the air system caught and killed 99.8% of COVID-19 particles in just one passing of air through the filter when it was at a temperature of 200 degrees Celsius. Therefore, the temperatures currently listed for the air disinfection system is more than enough to kill the coronavirus on contact.
Traditional air conditioning filters are made of fiberglass or aluminum mesh, which is difficult to heat or contains large pores (of about 1 cm in size) that cannot effectively trap and kill viruses. Researchers noted that it would be ideal for a filter to be self-heating rather than having an external heat source that would cause a rise in air temperature. For this to happen, it would require the filter itself to be electrically conductive.
Commercial nickel is electrically conductive and mechanically strong enough with good flexibility. These properties ensure that it can be used in energy conversion and storage applications. Additionally, nickel has large pores that are randomly located, resulting in a large surface area that can catch particles from air that passes through.
The self-heating aspect has the additional advantage of the heat being localized on the foam and then transferring to passing air, which minimizes the contact time between air and the foam. Because of this, nickel foam acts as an ideal filter for catching and killing the coronavirus.
However, researchers note that it’s not easy to design a filter like this because the nickel foam is too small to heat at high temperatures. To accommodate for this, researchers designed a filter that is made of folded pieces of nickel foam in several compartments and connected it electronically to effectively increase the temperatures to 250 degrees Celsius. Using this method, researchers were able to catch and kill nearly 100 percent of airborne SARS-CoV-2 and anthrax spores.
Nickel is also the best material for the air filter to be used in air conditioning units. For a heated air disinfection system to be used in air conditioners, researchers must take into consideration the temperature of the air after it passes through the nickel foam. If the air temperature is too high, then the nickel foam would not be a good option. After testing the nickel foam, researchers found that air temperature decreases very quickly after passing through it, even at high temperatures of 115.3 °C. The researchers noted that air temperature inside ductwork might be higher than in an open air environment.
Although the new air disinfection system is a step in the right direction, more testing for similar devices and technology is needed to stop the spread of the coronavirus. According to co-founder of #GetUsPPE and Associate Professor of Emergency at Brown University Doctor Megan Ranney, the new air filter is another piece of the puzzle when it comes to reducing the public’s risk and exposure, but it’s not a stand-alone approach by itself.
Doctor Ranney stated that a filter alone is not enough. Masks and other testing are still needed to fight the public health crisis. Doctor Ranney continued by saying that if it works, this type of filter could help decrease the amount of virus that circles in a closed space. However, it two people are talking face-to-face, and one coughs on the other, there is no filtration system in the world that could protect the coughed-on person from potentially being infected.
Doctor Ali Raja, Associate Professor of Emergency Medicine at Massachusetts General Hospital, Harvard Medical School and Executive Vice Chair of Emergency Medicine, agrees with Doctor Ranney’s position. Doctor Raja stated that if the air filter works as it is designed to in the study, then it could be a game changer for catching and killing COVID-19. However, infected patients, especially those who do not show symptoms, could still spread the virus to people around them before the air gets filtered. This means that people still need to wear masks.
Doctor Raja added that while such an excellent air filter system will make reopening public transit, schools, and businesses safer, the question is to what extent. This new filter could help society reopen closed spaces a little more safely. However, people in these spaces still need to wear masks as the virus particles from the lungs can be expelled with each and every breath, stated Doctor Raja.