Since Florence Nightingale in the 1850s, ventilation has been seen as key to a healthy indoor environment. “Unless the air within the [hospital] ward can be kept as fresh as it is without, the patients had better be away,” she wrote.
Many others have adopted ventilation as the quickest, easiest path to healthy indoor air quality . For example, in their 2020 book Healthy Buildings, Joseph Allen and John Macomber wrote, “We give the economic evidence demonstrating how even just one building factor – ventilation – can lead to significant enterprise-wide gains, and show you how to create and capture this value.” They further point to the evidence that increased ventilation can improve the health and performance of students and employees.
Ventilation is certainly the only way to deal with elevated CO2 levels; no air purifier can remove CO2.
However, as climate change accelerates and wildfires become more intense, the limitation to ventilation as a one-size-fits-all approach to IAQ is becoming apparent.
First, even if outdoor air were as perfectly clean and fresh as in Florence Nightingale’s time (and it wasn’t always so clean even then, with the abundant burning of coal in furnaces and factories), we hear from many facility managers that it is expensive to ventilate. In our increasingly hot summers, up to 27% of a commercial building’s energy use goes to air conditioning. Heating can be even more expensive, and can account for up to 45% of a building’s energy use in the winter months. This “ventilation penalty” is considerable. That’s a lot of money and carbon flying out the window.
And what if, aside from reducing CO2, opening the windows and HVAC vents was actually making the indoor air less healthy?
The American Lung Association says that over a third of Americans live in areas with unhealthy outdoor air. Typically, indoor pollution levels are at least 50% as high as outdoor ones.
This past summer the Midwest and East were blanketed by thick smoke from Canadian and Western wildfires. New research by Metalmark shows that wildfire smoke consists primarily of extremely small particles — .3 microns or smaller. According to a 2020 article in Nature, these tiny particles are especially dangerous, given their ability to pass through the lining of the lungs and into “essentially all organs. Compared to fine particles (PM2.5), they cause more pulmonary inflammation and are retained longer in the lung. Their toxicity is increased with smaller size, larger surface area, adsorbed surface material, and the physical characteristics of the particles.”
Metalmark’s research also found that typical IAQ monitors measuring PM2.5 particles won’t detect these dangerous particles. And typical HVAC MERV filters rated 8-14 can’t filter most of them out.
And a recent study from Harvard T.H. Chan School of Public Health based on Medicare data from millions of people aged 65 and older, found that long-term exposure to supposedly “safe” levels of PM2.5 and NO2 over 10 years led to elevated levels of breast and endometrial cancers. They were only looking at PM2.5; imagine what they would have found if they could have studied PM1.0 and ultra-fine PM.01. There may be no “safe” level of air pollution.
In 2023, ASHRAE released Standard 241, which for the first time acknowledged that healthy indoor air can be achieved through various combinations of ventilation and air purification. While focused primarily on reducing the indoor threat from pathogens such as COVID, its approach is equally useful in dealing with other harmful PMs, from day-to-day pollution to wildfire smoke. It introduced the idea of equivalent clean airflow, which it defines as “the theoretical flow rate of pathogen-free air that, if distributed uniformly within the breathing zone, would have the same effect on infectious aerosol concentration as the sum of actual outdoor airflow, filtered airflow, and inactivation of infectious aerosols.”
It also introduced ECAi, the “required equivalent clean airflow per person for infection risk mitigation.”
Only HEPA filters, like those used in Metalmark Tatama, remove virtually all particles and pathogens.
Tatama Air Cleaner
For commercial new construction or retrofits into existing facilities
Tatama uses Metalmark’s advanced HEPA-grade filters to capture airborne particulates, smoke, VOCs, and pathogens, including viruses and bacteria.
Sierra Air Filters
For your existing commercial HVAC systems
The HVAC filter with enhanced protection against wildfire smoke. A simple drop-in replacement with no change to air flow or pressure.
