What is a PM2.5 Air Filter?

Jessica Shea Choksey | Dec 21, 2020

Just like with your home or any other interior space, an automobile uses a filter in conjunction with its heating, ventilation, and air conditioning (HVAC) system to help clean incoming air as it enters from the outside. But a standard air filter may not be an effective enough barrier against fine airborne particulates known as PM2.5. This designation refers to particles of matter that measure 2.5 micrometers in size, including combustion emissions, organic compounds to which viruses may attach themselves, and certain metals.

PM2.5 Air Filter Monitor in a Volvo

These harmful aerosolized particles can pass through a standard air filter’s cotton and polyester layers with little resistance. Prolonged exposures to this kind of pollution can negatively affect an individual’s respiratory system and cardiovascular health, allowing fine particles to get deep into the lungs and even into the bloodstream. These health risks can increase due to sitting in rush hour traffic frequently or navigating long highway commutes daily, as dense traffic often creates the highest pollutant concentrations.

Roadside PM2.5 particulate matter sources include automobile tailpipes, construction sites, unpaved roads, smokestacks, fires, and industrial plants. When on the road, the best way to reduce exposure to outdoor pollutants is to keep the windows closed and set the vent to recirculate cabin air.

If a PM2.5 cabin filter is available for your make and model of car, consider replacing the vehicle’s standard air filter, which is typically designed only to capture larger PM10 particles such as dust, pollen, and mold. Able to filtrate the cabin air to a much higher degree, a PM2.5 filter has two layers of mesh made from non-woven fibers that will “catch” tiny particulates coming through the HVAC system. Furthermore, the fibers are electrically charged, which means the filter uses electrostatic attraction to capture smog particles, much like a magnet. This technology is similar to that of medical-grade N95 masks used in hospitals and healthcare facilities.

The static and the non-woven fibers together provide an elevated defense that is more advanced than standard air filters and HEPA filters. PM2.5 filters are known to achieve up to 90% effectiveness in the filtration of smog elements in the sub-micron range, the smallest of the small particles flying around in the air.

Some vehicles with advanced air purification systems can elevate PM2.5 filtration up to 99% effectiveness. These systems use cabin sensors to automatically shut down the external air supply and recirculate clean air. Under normal operation, incoming air first comes in contact with an ionizer, which attracts the tiny pollutants to an opposing charge filter plate. The air then passes through a PM2.5 cabin filter and enters the occupant compartment.

Many vehicles do not offer PM2.5 filters. Check with your manufacturer or a local auto parts retailer to determine availability for your make and model. In place of a PM2.5 air filter, an equally-rated in-vehicle air purifier is a suitable alternative.

Regardless of what kind of cabin air filter you are using in your vehicle, consult the owner’s manual to locate and replace the filter. In most cases, the recommendation is to change the air filter every 12,000 miles, but consider a shorter interval if you or others you drive with have underlying respiratory issues. You may also want to change the air filter more frequently if you regularly drive in heavy traffic or through smoggy areas often.

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