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Factory-installed cabin air filters allow ultrafine particles to enter through the vents in your vehicle, but a new HECA filter improves the air. Credit: Image adapted from Zuzu; Wikimedia Creative Commons License.

The next time you can’t decide what to order while sitting in the drive-thru at Wendy’s, consider blaming your air filter.

A vehicle’s cabin air filter is designed to filter out harmful small particulates, namely dangerous ultrafine particles (UFPs), but it isn’t very efficient—most OEM filters only block about 50% of particulates. Vehicle emissions are a primary source of urban UFPs, which are consistently elevated around urban highways, so that means you’re breathing in a lot of those particulates each time you ride in your vehicle. And though switching your air vent to recirculation mode can block the entry of around 90% of UFPs, doing so quickly runs up dangerous carbon dioxide levels—which inhibit decision-making. You just can’t win.

Take a deep breath—a couple of scientists at UCLA have devised a solution. “To address this challenge, (the authors) Zhu and Lee decided to develop a method that would simultaneously reduce UFPs inside cars, while also allowing carbon dioxide to escape,” states a press release from the American Chemical Society.

The duo developed a high-efficiency cabin air (HECA) filter that can reduce cabin UFP levels by an average of 93%. Breathe that in. Published in Environmental Science and Technology, the study describes the design of a dual-layered filter composed of upstream synthetic fibers and downstream glass fibers, in comparison to the standard single-layer of OEM filters. The scientists also decreased the diameter of the fibers to increase particulate-nabbing surface area.

Zhu and Lee then put the filter to work, testing it out in 12 different vehicles under stationary, local road, and highway conditions, using condensation particle counters to measure particulate levels inside and outside the vehicles.

The tests showed great results across the board, with the HECA filter able to significantly reduce cabin particulate levels and prevent buildup of carbon dioxide. As the authors conclude in the paper, “Overall, the developed HECA filters achieved 2−3 times greater reduction than the in-use OEM filters.”

UFPs, which are defined as being less than 100 nm in diameter, pose a significant health risk because their small size allows them to easily enter the respiratory system. There, within the aveoli of your lungs, the particles’ small size further allows them to diffuse or transport across cell membranes, entering the intracellular space and gaining access to important cellular stuff, like DNA. Once on the inside, UFPs might induce or catalyze of wide range of cellular changes, including inflammation, oxidative stress, and epigenetic modifications.

UFPs are generated from a variety of sources, which include both natural (think volcanic eruptions and sea spray) and manmade (combustion reactions and friction) processes, but vehicle emissions constitute a large proportion of urban UFPs. Considering the estimated 38 hours per year the average American spends stuck in traffic, reducing vehicular exposure to UFPs could provide great health benefits.

The paper is “Application of a High-Efficiency Cabin Air Filter for Simultaneous Mitigation of Ultrafine Particle and Carbon Dioxide Exposures Inside Passenger Vehicles” (DOI: 10.1021/es404952q).

 Feature image credit: Image adapted from Lazy Lightning; Wikimedia Creative Commons License.

Credit: Zuzu; Wikimedia

Honda Credit: Lazy Lightning; Wikimedia