Keeping Our Homes Air Pure & Safe

ByMarc Silberberg


“Run and get an air purifier”, was the answer to the question that Lisa asked her mother about getting together for the winter holidays. Lisa brought up the suggestion of the family getting together on a smaller scale this winter. She was surprised that her Mom would even consider coming to her home this season. Lisa had assumed that she would get together with her siblings and their families and zoom their parents. Her Mom would have none of that. No way would Lisa’s Mom miss out on the only day of the year that their entire family gets together. Would an air purifier save the day?

It is surprising that air purifiers and HEPA filters (high efficiency particulate air) for central air conditioning units were not being advised as early as March of this year. It is true that as the weather warmed up, homeowners and apartment dwellers could have technically opened their windows to let in fresh air that will circulate around the house. Realistically, however, how many people today open or can open their windows in the warmer weather? For safety or logistical reasons (office buildings have windows that do not open), many places have the same stale air circulating constantly.

According to Richard Corsi, the dean of Engineering and Computer Science at Portland State University, masks reduce the risk of contagion by at least fifty percent and an air cleaner could reduce the risk to over seventy-five percent. With even more ventilation, the likelihood of catching a disease could decrease up to ninety percent. Remember, Corsi is including a mask in his statistical analysis.

There are different types of air cleaners such as air filters, air purifiers and ionizers.

Air Purifiers

The most efficient air purifiers will trap airborne particles as small as 2.5 micrometers, to protect the lungs against hazards such as cigarette or fire smoke and especially viruses and diseases. The better air purifiers can catch extremely small particles such as COVID-19 aerosols. This virus is always released together with a small addition from the human body, such as hair, saliva, or mucus. So even though the virus itself is only about .1 micron (1/1000th cross section of human hair) it is attached and “it will not survive outside that particle”. Most air purifiers are portable and can be moved from room to room as needed although there are some that can be fitted as part of your present HVAC system . Joseph Allen, a science professor, suggests that using a portable air cleaner costing a few hundred dollars with a HEPA filter will destroy 99.97% of disease bearing germs including the tiny droplets that cause the virus.

When shopping for an air purifier check on its specific filtering expertise. Each purifier is specified for different types of pollutants. Presently, stores will be knowledgeable as to which air purifiers would be best to kill the COVID-19 virus effectively.

“It’s Not an Air Purifier It’s a COVID-19 Killer”

This was an announcement made in Galveston, Texas recently. A company based in Houston called IVP has invented a series of air purifiers capable of servicing buildings as large as schools, hotels, and convention centers. A Galveston public school official learned about this new air purifier from the Intercontinental Hotel and the George Brown Convention Center as well as a north Texas school which had these devices installed. The purifier looks like a huge hot water tank in the corner of the classroom and was built to specifically kill the COVID-19 virus in the air. According to the inventor, the device circulates one thousand feet of air every hour. Some of these units will be transferred to different areas during the day such as auditoriums and cafeterias. It cost the Galveston lower school system one hundred thousand dollars to install the units. Now they are looking for public funding to install one in every school in the district. The company is so sure their device is an actual COVID-19 killer since it was tested in a National lab twice.

Air Filters

Most regular cooling and heating systems for the home recirculate the same air repeatedly. The pollen, dust, dirt, and especially airborne viruses keep moving around. If the windows would be open, then of course you could have fresh air circulating but then you would not need your heat or air conditioning working. Built right into your HVAC systems are air filters or air cleaners. For your home, any type of filter from fiberglass to carbon will effectively keep the air in your home clean. Every time air is drawn through the ducts, the air is filtered bringing you cleaner air and preventing impurities from entering your home.


Another effective way of killing the COVID-19 virus are devices called ionizers. By charging the air particles with an electric charge is the way an ionizer kills the virus. Ions, or charged particles are positively or negatively charged. Since opposites attract as we learned in school, a positive ion will be attracted to a negative ion. The ionizer will give the tiny airborne droplets a negative charge. Then a plate that is positively charged will suck these particles out of the air, into the plate and ready for disposal.

Do You Need an Air Cleaner in Your Home?

There are several factors that will determine if you need an air cleaner of any kind in your home. The simple answer would be why not if there is a chance to keep your family safe from getting sick with the dreaded COVID-19 virus. There is certainly nothing negative or dangerous about these air cleaning devices. However, experts differ if they are necessary in certain homes. If you are living in the type of home where you air out your house daily by opening your windows you are already purifying your air. Do you have strangers coming in and out of your house on a regular basis? If you are retirees and it is just the two of you, it may not be necessary. However, even if you have the house cleaner or plumber or other helpers coming in on a regular basis your risk increases. Let us say that one member of your family works in a hospital or nursing home or you have children who go to school it would be a prudent investment. Masks are helpful but not a secure way of preventing a hundred percent of the aerosols from entering your home. In an average home it takes approximately two to three hours for air to be exchanged. If you add an air purifier the air will be cleaned about every ten minutes.

Let us get back to Lisa and her Mom at the start of this article. Richard Corsi and Joseph Allen are both advocates of home air purifiers. However, they caution strongly not to have company, just because you have a purifier running in your home. “Having people into your home for a meal or perhaps staying several days is a big concern as holidays approach,” says Corsi. “Some may have been exposed; others don’t even know they are infected.” They caution that if you do decide to have visitors you must still wear a mask and wash your hands even with an air purifier.

When deciding to purchase an air purifier know that it is like purchasing a portable air conditioner; you must calculate for the correct size. The Harvard-Cu Boulder Portable Air Cleaner Calculator will work for you even though it was originally created for larger institutions. This is a download on the computer for which you put your specific home data into yellow boxes. You will be required to measure your ceiling height, room size and what type of ventilation you presently have in your home.

On the package of a purifier is a number called, CADR (Clean Air Delivery Rate). The higher the CADR the more air will be exchanged per hour. An efficient index would be three to five air exchanges per hour. With a quality purifier the CADR will be specified on the package. If it is not, then Corsi suggests you do not buy it. He recommends a CADR of 250 to 300 or higher.


At the time of this writing, we are still not sure who will be our next president. Joe Biden is getting ready to move into the White House and if he succeeds, we can be sure there will be run on air purifiers and some contractors will get rich. So far, his team is acting on making the White House COVID-19 free. A team led by the General Services Administration plans to go through every part of every wing that was touched by human hands. This includes disinfecting all light switches, doorknobs, handrails, and furniture before Biden will agree to set foot into his new residence.

Depending if you are from the masking or no masking camp will determine how you feel about these developments. Biden did succeed in not contracting the COVID-19 virus during his limited campaign, however, I’m not sure how he will be able to meet with foreign leaders. Hopefully, he will be vaccinated and that will take care of this problem. We must all pray that the vaccine is the answer, but I have a feeling that sanitizers and air purifiers are here to stay.

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