Sitting in traffic? You need cleaner air in your car. Follow our safe driving tips and read our review of Bosch’s HEPA cabin air filter so that you and your passengers can breathe easier.
Vehicle emissions (e.g., fine particulate matter (PM)) contribute to outdoor air pollution, especially along congested roads. But did you know that when you sit in traffic, these emissions can also make the air inside your car unhealthy to breathe? Even if you recirculate your air when you sit in traffic (which is our strong recommendation), you can still benefit from having a cabin air filter designed to meet HEPA standards and remove small particulate matter from the air inside your car. This is important, like wearing your seatbelt, properly inflating your tires, and putting your younger children in car safety seats. For this reason, we decided to test one of the few HEPA cabin air filters on the market.
For millions of Americans, driving on congested roads and freeways is a way of life – a daily grind that the Police famously compared to being “packed like lemmings into shiny metal boxes.” There is no question that driving in heavy traffic on the way to and from work, kids’ schools, and afterschool activities can take a mental toll. But many drivers may not know that it can take a heavy physical toll as well: With their vents open, they are actually endangering the health of everyone in the car because they are breathing the polluted air around them.
While technologies to curb large particulate emissions from vehicle exhausts have been successful in reducing air pollution, research has provided insight into the health impacts of particulates that are invisible to the naked eye and still emitted by vehicles – fine particulate matter PM2.5 and PM10 (smaller than 2.5 microns and 10 microns respectively). These pollutants can cause respiratory illnesses and have been linked to up to 3.3 million premature deaths worldwide despite the advances in emissions control. Since these pollutants are out of sight, they are largely out of mind for the public, notwithstanding that they literally surround us when we drive on congested roads.
Almost all vehicles manufactured since the last 1990s are fitted with a cabin air filter that filters out pollen, other large particulates and certain odors. However, few cabin air filters have the ability to protect a vehicle’s occupants from fine particulate matter and other pollutants. Manufacturers are beginning to address this issue by releasing HEPA compliant filters. However, these filters are not available for every vehicle. Moreover, you may need to install these filters yourself because they are not typically included as standard equipment on new cars, nor are they typically incorporated into dealer maintenance programs.
How do I protect myself while driving?
There are several ways to reduce the amount of harmful pollutants that you breathe while on the road. These include:
- Avoid driving in heavy traffic to the greatest extent possible. This is one reason we recommend checking traffic before every drive.
- If you must drive in traffic, follow our safe driving tips: Set your air vent to recirculate with your windows up just before you hit the traffic on the road. Researchers from USC have found that having your air vents open to draw outside air will fill the interior of a vehicle with 60-100% of the outside air and the pollutants it contains, meaning you might as well have your windows down. However, if you put your vents on recirculate with the windows up, the indoor-to-outdoor air ratio improves dramatically (meaning you are breathing much cleaner air), with the greatest air quality benefits seen at slower speeds in newer cars (as vehicles age, their seals become less air-tight).
- But remember: Depending on the number of occupants in your car, you will need to open your vents for a few minutes roughly every 30 minutes to avoid dangerous carbon dioxide levels building up inside your car. The best time to open your vents is when you hit a stretch of faster moving traffic with more spacing between vehicles.
- Install a HEPA rated cabin air filter in your vehicle if available for your make and model. This will protect everyone in the car both when the vents are open and when they are set to recirculate (because air is still passing through the cabin air filter in this mode).
Bosch, a major manufacturer of automotive parts, has created a cabin air filter that their testing has shown meets the relevant HEPA standard – filtering out 99.97% of all particles down to 0.3 microns. HEPA (high efficiency particulate absorber) is a standard set by the US Department of Energy and any filters that are certified HEPA must meet or exceed these standards to obtain the certification. Therefore, these filters have the ability to filter out harmful particulates such as PM10 and PM2.5.
Tell me more about these filters!
Bosch HEPA filters are easy to install (for most vehicles) and are made for a variety of newer and popular vehicles. We obtained two filters to test the ease of installation and determine whether there are any downsiders to these filters as some early adopters of HEPA cabin air filters have complained that they produce squealing noises and/or substantially reduce air flow. The filters were comparably priced to non-HEPA cabin air filters.
Our two test vehicles:
- 2008 Toyota Highlander Hybrid
- 2015 Lexus RX350
On both vehicles, the cabin air filter is accessible via the glove box and the filter can be installed in less than 5 minutes. Neither installation required tools – you simply push in the hinges of the glove box to detach it and expose the filter panel, which is right behind the glove box. All you need to do is make sure you place the filter with the correct side up, which is clearly indicated on the filter itself. You do not have to be a dedicated DIYer to change your own cabin air filter.
We have driven four weeks with the filters. On our two test vehicles, there have not been any squealing noises. However, we have noticed what feels like a very slight decrease in fan power, although it is not substantial enough to impact passenger comfort in either car. Although we are months away from needing to replace the filters, it is worth nothing that with a HEPA filter, you may need to replace it every year or 12,000 miles because it will be trapping a lot of particles that would otherwise be inside your car cabin. In the grand scheme of things, these are small prices to pay for improved air quality and health.
Is it available on my vehicle?
For more information regarding the Bosch filters and their availability for various makes and models, please check out Bosch’s website here. Once you have the filter number that matches your vehicle, please visit our Shop to order the filter you need. As other HEPA cabin air filters come to market, we will update our testing.
If the filter is available for your vehicle, we highly recommend getting it. This is especially true if you drive a relatively newer vehicle (with newer and better sealing and weather stripping) in moderate to heavy traffic conditions on a regular basis. Even with a HEPA filter, we recommend recirculating your air with the windows up as much as possible when you sit in heavy traffic (and opening the vents as necessary to avoid carbon dioxide buildup).
If Bosch does not make a HEPA filter for your car, please set your air vents to recirculate as much as possible when you sit in traffic to reduce the pollutants inside your car. But remember to open your vents roughly every 30 minutes, with the best option being whenever you get a break in traffic.
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