By Jim Rosenthal, CAFS Several years ago I wrote an article for this website comparing different commonly available filters for resistance and efficiency (at 0.3um). The article continues to be one of the most popular on our site. There just aren’t many places where one is able to compare filters from various manufacturers. Somehow it … More
It’s All About the Air Flow Through the Filter
By Jim Rosenthal, CAFS Users of air filters – whether they are residential or commercial – are not interested in filter efficiency. Efficiency is just a number. What they are interested in is whether or not an air filter will protect their HVAC system and provide better indoor air quality in their home or building. … More
How to Improve the Efficiency of the Corsi-Rosenthal Box Air Cleaner
By Jim Rosenthal Several months ago I wrote two articles for this site on the “Box Fan and MERV 13 Filter” air cleaner. They have been viewed over 30,000 times and many people have built these air cleaners following the simple directions in the articles. They are easy to construct, inexpensive and effective. In short, … More
A Variation on the “Box Fan with MERV 13 Filter” Air Cleaner
The “Box Fan with a MERV 13 Filter” air cleaner is an easy-to-assemble, inexpensive and effective way to improve indoor air quality and to reduce exposure to Covid-19. The concept is really simple – attach an effective air filter to a box fan and clean the air. This article gives more details about the construction … More
Face Shields Should Not be Worn Without Face Masks – Here’s Why
There continues to be a dispute about whether a face shield (sometimes called a “visor”) is as effective or more effective than a face mask. Frankly, I do not understand why. Face shields will not protect someone from airborne Covid-19 – period. A face mask must always be worn with a face shield. This is … More
Using Filtration, Ventilation and Differential Pressure to Slow the Spread of Covid-19
By Jim Rosenthal, CAFS As of today, August 8th, US health officials have reported nearly 5,000,000 cases of Covid-19 (officially SARS-Cov-2). Deaths are over 161,000. This is not just the flu. One of the reasons the disease has spread so fast and so widely is within-household transmission. It is estimated that one in five people … More
How a MERV 13 Air Filter and a Box Fan Can Help Fight Covid-19
By Jim Rosenthal, CAFS A MERV 13 filter and a box fan? It is definitely not a new idea. It has been floating around for years. However, in the era of Covid-19, it is time to take all of the tools out of the toolbox. This simple, inexpensive air cleaning device can remove substantial amounts … More
The Adventures of “Hairy Manne” or Why you should always wear a face mask with a face shield – Continued
(Caution: Wearing a face shield without a mask could be hazardous to your health) By Jim Rosenthal July 14, 2020 – Canton of Graubunden, Switzerland Local health officials spoke out against face shields. In a recent Covid-19 outbreak at a local hotel all of the employees who were infected had been wearing face shields without … More
Understanding How HEPA Air Filters Remove Covid-19 From the Air
By Jim Rosenthal, CAFS “HEPA filters remove particles down to 0.3 microns. COVID-19 viruses are 0.125 microns so a HEPA filter cannot remove them from the air.” The above statement is often found in news articles about COVID-19. It is WRONG! HEPA filters remove over 99% of 0.125 micron sized particles! Even in well researched … More
Does Reducing PM2.5 in Air Pollution Lead to Better Health Outcomes?
Higher levels of PM2.5 have been shown to cause negative cardiovascular and respiratory health effects. Consequently, commercial and residential standards are being set to reduce PM2.5 exposures with the intent of improving health outcomes. This may or may not be a valid approach. Here’s why: All PM2.5 is not the same. The negative health effects … More