Even with higher MERV filters, new research shows HVAC systems vulnerable to small particles in wildfire smoke

The exceptionally small particles in wildfire smoke present a far greater health risk than facility managers might suppose. Sissi Liu is trying to do something about it.

Liu is the co-founder and CEO of Metalmark Innovations, a Boston-based climate tech company whose new peer-reviewed research has sounded an alarm about the dangers of wildfire smoke.

Among the most concerning findings by Metalmark scientists:

• Wildfire smoke is composed primarily of particles far smaller than previously believed, around 0.3 microns. These particles can easily pass through cell walls and cause severe medical problems, such as cardiovascular and respiratory diseases.
• Most HVAC MERV filters, made of synthetic (polymer) electret media, don’t effectively capture such small particles, leaving people who are indoors still exposed to the dangers of wildfire smoke. The electret filters actually lose efficacy as they collect smoke particles.

Even what seems like good news isn’t so good. Filters with fiberglass media were found to be more effective. However, their use causes much higher resistance to airflow within the HVAC systems in institutional and commercial facilities, decreasing the overall HVAC performance, increasing energy use and costs, and reducing the equipment’s lifetime.

Wildfire smoke is everyone’s problem now, regardless of location. It can travel thousands of miles, and Liu saw that for herself on a cross-country trip in 2021, when the Dixie Fire was the second-most destructive wildfire in California history.

“There were national parks just blanketed with smoke,” she says of her trip.

Indoor air quality, too, has received much greater scrutiny since the worst of the COVID-19 pandemic in 2020-21.

“Two or three years ago, there was a very different conversation about indoor air quality,” says Tanya Shirman, a materials scientist and vice president for Metalmark.

On June 7 of last year, on the second day of a wildfire smoke emergency, New York City posted an Air Quality Index rating of 342, giving it the most dangerous air of any city in the world. (A rating exceeding 301 is considered hazardous.) Even healthy individuals complained of burning eyes and coughing.

New research by Cornell University, Nanjing University of Information Science and Technology and the University of Houston found that particulates from wildfire smoke could lead to as many as 9,000 premature deaths and cost as much as $82 billion per year in the United States.

Metalmark, a small-business spinoff of Harvard University, is working on answers.

“We actually have a system we’ve been piloting that can remove particles and is low-maintenance,” Liu says. “Also, we plan to market a drop-in filter with enhanced protections to work with existing systems, with no change to the flow rate and pressure. It doesn’t increase energy, it maintains CFM and it boosts protection against smoke.”

Facility managers, she said, need to understand that MERV ratings don’t tell the whole story regarding wildfire smoke and the health dangers posed by its particles. Typical commercial MERV filters rated 8-to-14 can’t filter out most of them, she says.

In 2023, the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) released Standard 241, which for the first time acknowledged that healthy indoor air can be achieved through combinations of ventilation and air purification. Although the focus primarily was on reducing the threat of pathogens such as COVID, it also applies to day-to-day pollution and wildfire smoke.

By Doug Carroll, Contributing Writer

Doug Carroll is a freelance writer based in Chandler, Arizona.

The post "Wildfire Smoke: A Billions-of-Dollars Concern for Facilities" appeared first on Building Operating & Management