Germs and Smoke
October 28, 2020
Paul Herscu ND, MPHHerscu Laboratory
Air purification from September, 2020 –April, 2021: Germs and Smoke
This is a follow-up to the post on this topic from September, but an urgent one for two reasons. First, there are fires raging in the west of the United States leading to smoke entering homes irritating the respiratory tract of many people. And as importantly we are in the midst of a second wave of viral activity which has not come close yet to peaking. I am not focusing here on mounting virus activity or on changing morbidity/mortality rates, but suffice to say, the second wave has arrived, on schedule, as we predicted earlier this year.
The overall topic of this post is mitigation. Sometimes we find ourselves in situations where the water we drink, the food we eat, or the air we take in is less than optimal and if possible we need to mitigate or modify our exposures so the possibly harmful impacts are minimized. I would like to focus on air quality today and how both smoke and viruses impact air quality.
Over the past many decades, I have been impressed by public health infrastructure and work accomplished in the USA and abroad developing processes that help many people and communities, those with means and those without. It is impressive to examine the ability for governments to intersect with NGOs and stakeholders in an ever-evolving partnership to offer health and safety quickly and efficiently.
And there are areas where we could do better and occasionally there are quick, easy, inexpensive do-it-yourself solutions for a challenging issue.
I describe here one such idea, born from current need: an economical, home-made, Box Fan - Air Filter System.
I received an email from a patient describing how bad the smoke is from the fires burning all around her city. And though she does not go outside much, smoke is irritating her eyes, nose and throat. She has tried several solutions in her space, but the problem persists. And also, she lives in an apartment complex, and does not control central air solutions for the apartment. Even if the owner would want to consider such an investment, professionals doing that work are quite busy now, and new projects would likely be put on a waiting list. But the problem exists right now. What to do?
I received other calls from people who have to go to work, people who are going to family gatherings, and even small medical clinics, where the caregivers all feel appropriately at risk. Doctors are calling to tell me that while they feel their work is vital, in small private clinics, where they cannot control air flow, they feel at dire risk. This is true in naturopathic, acupuncture, and body work offices for certain. Many colleagues have asked what can they do. Likewise, people in small shops who can not afford to close and can not afford expensive alternatives ask the same question.
Lastly, other people tell me that they live at university dormitories where that cannot control air purification, and that there is mold in the room. Others tell me of mold in the house. Others tell me that during hay fever season, they are desperate for a reprieve from the exposure to pollen. What can they do?
Others feel like they are at risk. They physical distance as best they can, they wear masks, but they have to go to a small wedding party, or Thanksgiving or holiday meal or visit an ailing family member. Is there something they can do to help, above and beyond what is already suggested?
Here is a simple, affordable, temporary solution that can help mitigate the air quality that people in a given room are exposed to. There may be a few public health authorities mentioning this, but in fact this kind of recommendation has to date not been generalized and most people are surprised to learn about this simple idea. While I was not the first to create this solution, I really want to publicize this again, and attempt to generalize this now.
The most important aspect of the solution is that you want to remove particulate matter from the air inside the house or space you are in. Good quality air filter machines will do this, but cost $500-$2,000, and you might have to bring in filtration systems to each room of a house or apartment, which is too costly. It can be difficult to purchase and install without further expenditure. I will come back to this point below. But in many ways, we are attempting to mimic a high-end, large-facility air purification system, as a do it yourself project.
Here we go! Buy a box fan. Yes, those old-fashioned fans —you might even one lying about a basement or garage or storage area. These can be bought for $10-$40. Secondly, purchase a 20 inch by 20 inch air filter which will cover the overall surface of one side of the fan.
The filters come in different sized mesh, smaller mesh captures smaller particles. Look for the smallest mesh as this will also remove bacteria, mold and viruses as well as smoke and other pollutants. You will be removing particulate matter. Look for a filter that has at least FPR 10 or MERV 13 or higher number. This may be hard to find just now, so you might have to use a FPR 9, but aim for the MERV13 or FPR 10.
When you get home, unpack the filter, place it, then using packing tape, tape it to THE BACK OF THE FAN, not in the front of the fan. This way the unfiltered air moves through the filter so cleaner air is blown out from the fan into the room.
Note that the filter is made to have air flow in one direction. Look at the edge of filter to find an arrow that shows the direction of airflow. Point the arrow towards the fan when you tape it to the back of the fan. As you tape the filter to the fan, use the packing tape to close the gap space between the fan and filter, since the filter will fit fairly well, but not perfectly. Don’t worry if it is not 100% covered, it will still work! You want to force the air to go through the filter and not around it.
This will work REALLY WELL for any one room. Don’t leave this on when you are not in the house. Fans have electric motors and should only be used when you are present. Keep children away from the fan. For $30-$50, per average sized room, you can dramatically reduce the amount of smoke and other particulate matter in your home and work space. Do not aim the fan directly at people.
Regarding viruses and the current upsurge in cases. Logical distancing between people makes sense, and let’s take 2 yards/meters as a typical suggestion. Adding a mask is as if you added more ‘effective’ yards between people since the mask lessens the amount of germ spread. And here, consider this removal of particulate matter as ‘effectively’ adding many further yards between people. In those situations where contact is unavoidable, and you are doing everything you can, consider adding this air purification system.
Why this is a new solution? We live in a variety of structures. In some instances, you may live in a condominium or work in an office space or factory where there is a central control, central air. Depending on the type, it is very likely or possible that the system cannot handle a MERV 13 or higher filter. The filter may create too much air resistance for those systems to handle and they may be damaged. Or if working within air-conditioning systems, the filter may cause freezing, or overloads in different parts of the system. In other words, the system your space uses might be great, but not able to remove these small particles or viruses because it cannot handle this level filtration. It is also possible that your system might be able to handle it, but the person in charge of managing this is overworked and does not get back to you in time, and time matters here, just now. This is quick and easy to set up.
Do know that taping more than one filter will not make things work better and in fact will put too much strain on the fan. One filter will suffice.
The debate on whether the current virus is transmitted commonly via droplets or also by aerosols continues to rage. This is actually a very important topic which I teach upon in-depth. The topic fits squarely on Contact/Noncontact transmission. There is one point that I want to highlight here, something that has not really been highlighted. Filtration of the type I described clearly removes large particles, but what of the aerosolized particles? I think it helps here as well in two different ways.
First the higher the filter number, the smaller the particle size is that is removed and that by itself is very good. But perhaps as importantly, the aerosolized small particle often ‘binds’ to other molecules and those particles travel. And by removing those other particles, the virus has less things to attach to. In other words, removing large and small particles can help in both droplet and aerosol transmission reduction.
As an experiment, I purchased a professional laser particle counter to measure the particles in the air in a room. It measures both large and small particles. And it dropped the ambient particle count by 70%-90%, with the more fans in the room the more dramatic and quicker the effect.
Click here to watch as I discuss and put together one such filter/fan.
I urge public health authorities to consider sharing such solutions especially at this time when so many people are in need and would do well to purify the air they breathe.
For more information, from other sources, describing the same process please see below:
Different structures: https://www.cct-enr.com/box-fan-filter
Air filter information: https://pscleanair.gov/525/DIY-Air-Filter
Questions for EPA about air quality in the house, including portable air filters: https://www.epa.gov/coronavirus/air-cleaners-hvac-filters-and-coronavirus-covid-19
Paul Herscu, ND, MPH