To Your Health: Indoor Air Filtration, Help with Covid & Smokey Air?

To Your Health: Indoor Air Filtration, Help with Covid & Smokey Air?

Part-time Telluride local, Dr. Alan Safdi, is a world-renowned internist and gastroenterologist with encyclopedic knowledge of mind-body wellness and preventative medicine. He posts regularly on Telluride Inside… and Out under the banner of “To Your Health.” His blogs feature the most current information in his field: health, wellness, and longevity. Which now has to mean Dr. Alan’s podcasts and stories are mostly about what’s on everyone’s mind: COVID-19. 

Links to Dr. Alan’s podcasts and narratives on COVID-19 are here.

This week in his podcast, Dr. Alan talks in depth about in-door air filtration. Do they help in these times of Covid-19, forest fires, and other pollutants?

Beyond the podcast: Air filters and pollutants, more:

Finally The Centers for Disease Control revised its Covid-19 guidelines to include the fact COVID-19 can be spread through aerosols, which “can linger in the air for minutes to hours and travel farther than six feet. High time as we have been discussing the dangers of aerosol spread for about 6 months in our podcasts.

To fully understand our most recent blog and the podcast it is important to know what a micron is in detail.

A micron is a unit of length that equals one-millionth of a meter. In other words, a micron is 1/26,000 of an inch. Generally, the human eye sees particles in the 50 to 60 micron range. A human hair may be in the range of  50-70 microns (approx. 20-170 microns) thick. Covid-19 is much smaller than a bacteria, a red blood cell, or a droplet of fog.

Pollutants such as smoke from wildfires, tobacco, wood burning, and cooking; gases from cleaning products and building materials; dust mites; mold; and pet dander all contribute to an unhealthy indoor environment with ill effects on human health.

But what about COVID-19?

The virus that causes Covid-19 is mainly spread through respiratory droplets expelled when an infected person talks, coughs, sneezes or breathes. These droplets can then be inhaled by anyone in the vicinity. But the virus is also spread through smaller airborne particles that have been “aerosolized,” lingering in the air for minutes, even hours.

Please do not be lulled into thinking air filters alone, of any type, are enough to prevent indoor spread of COVID. Size matters.

Air filters such as a HEPA filter can deal with extremely small particles down to .3 microns, removing 99.97 %, but the COVID virus is smaller at .125 microns.

Does that mean HEPA filters do not work at all?


Often Covid 19 is contained in a larger respiratory droplet, which can occur after coughing, sneezing, etc. as mentioned. In the case of these larger droplets a HEPA filter may be able to trap and remove the bad actors. Those particles which may be the most common means of transmission can be larger than .3 microns and therefore trapped by a HEPA. That said, some larger COVID particles settle to the ground so quickly air purifiers can’t capture them in time so good hygiene remains critical.

Fine particles, 10 microns in diameter or smaller, including those found in dust and smoke, are especially a concern too because they can find their way deep into the lungs. Breathing in particles for just hours or days is enough to aggravate lungs and cause asthma attacks, and has been linked to heart attacks in people with heart disease. According to the EPA, long-term exposure to high particle levels is linked to bronchitis, reduced lung function, and premature death.

A very scary study from about two years ago delineated the risk of dementia associated with air pollution.

In the study older women who live in places with fine particulate matter exceeding the U.S. EPA’s standard are 81 percent more at risk for global cognitive decline and 92 percent more likely to develop dementia, including Alzheimer’s. These very small 2.5 micron microscopic particles generated by fossil fuels get into our body directly through the nose into the brain.

When looking for a good Hepa filter air purifier consider the CADR which reflects, in cubic feet per minute, the volume of clean air that an air purifier produces on its highest speed setting. For example a CADR of 250 for dust particles reduces particle levels of dust to the same concentration that would be achieved by adding 250 cubic feet of clean air each minute.

Personally I like at least 180 and above and, yes, I own three Hepa filter air filtration systems.

Dr. Alan, more:

Dr. Alan Safdi is board-certified in Internal Medicine and in Gastroenterology and is a Fellow of the American College of Gastroenterology. A proven leader in the healthcare arena, he has been featured on the national program, “Medical Crossfire” and authored or co-authored numerous medical articles and abstracts. Safdi has been involved in grant-based and clinical research for four decades and is passionate about disease prevention and wellness, not just fixing what has gone wrong. He is an international lecturer on the subjects of wellness, nutrition and gastroenterology.

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