Do Car Air Purifiers or Ionizers Really Work?

Car air purifiers, ionizers, and ozone generators

Most people never think about the air quality inside their cars, but it is a subject that bears some attention. On average, we spend about 5.5 percent of our time in our cars, according to one study on the air quality inside vehicle cabins, which is a significant amount of time to seal yourself in with some pretty bad air.

Dealing With Bad Air In Cars: The Problem With Car Air Purifiers

Car air purifiers exist, and some actually work. The problem is that car air purifiers rarely work in the same way, or as well as the air purifiers you may use at home or work. If you're expecting similar results, you'll probably end up disappointed.

Therefore, it's important to temper your expectations when dealing with car air fresheners, purifiers, ionizers, and similar gadgets. Most of these devices are actually ionizers, which work using a different mechanism than the HEPA filters (high-efficiency particulate air) that are common in home and office environments.

The fact is that ionizers don't filter particulates out of the air, and even big, expensive units designed for home use have drawn the ire of consumer advocacy groups. They do work in that they do what they are designed to do, but that may or may not align with your expectations for an air purifier.

Other car air purifiers work by generating ozone. These devices can certainly knock out some powerfully baked-in smells, but they're typically better left to professionals.

car air purifier needed

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The Quality of the Air Inside Your Car

When most people think about air pollution, they think about smog, pollen, and other outdoor air quality problems. The next thing that typically comes to mind is indoor air quality, which usually becomes a bigger problem during hot or cold weather when dust and other allergens are allowed to collect inside homes and businesses sealed up against the elements.

Indoor air pollution is also a problem inside cars, so the idea of car air purifiers has a lot of merits. The same pollutants and allergens you find outside are present inside your car, in addition to chemicals and particulates that come from the car.

Another air quality issue that many people deal with involves lingering odors from tobacco and other sources. Purifiers and ionizers usually won't help with this type of problem, but you may have luck with adsorbents or ozone generators.

Types of Car Air Filters, Purifiers, and Ionizers

There are a few types of air filters and purifiers that you can get for a car, including:

  • Engine air filters: These filter the air that goes into the engine for combustion. They have nothing to do with the air quality inside the passenger compartment.
  • Cabin air filters: These filter the air that comes into your car when the heating, ventilation, and air conditioning (HVAC) system is set to draw in fresh air. They may also filter the air that is recirculated.
  • Air ionizers: These are electronic devices that are typically plugged into the cigarette lighter socket. They operate on the principle of ionizing pollutants and causing them to stick to surfaces where you won't be able to inhale them.
  • Ozone generators: These devices generate ozone, effectively destroying the molecular structure of pollutants and unpleasant aromas.

Each of these filters uses a specific method to perform a different function.

Air Filters in Cars

Engine air filters use a filtration media that is typically paper or cloth-based to trap particles and debris and prevent them from entering the engine's intake system. Unlike cabin air filters, engine air filters have nothing to do with the air inside the passenger compartment of a car.

Cabin air filters are an important part of maintaining an allergen and odor-free passenger compartment. Whereas older vehicles drew in fresh air through unobstructed exterior vents, newer vehicles use cabin air filters to trap particles and debris. Two kinds of cabin air filters may help reduce the allergens and odors in your car:

  • HEPA cabin air filters: These filters use a fine mesh to trap large particles, like pet dander, and tiny particles, like those found in tobacco smoke.
  • Cabin air filters with activated carbon-impregnated filtration media: Filters with activated carbon are especially good at eliminating odors.

Even when you set the HVAC controls to recirculate, the cabin air filter is still in play in most vehicles. This setting prevents new air from entering the vehicle. It simply recirculates the air in the cabin, so it can effectively prevent the introduction of new pollutants while filtering out existing pollutants.

Cabin air filters work better than ionizers, but you need to replace them regularly.

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Some vehicles, especially older vehicles, don't have cabin air filters. And some older vehicles that do have cabin air filters have them placed in a location where they cannot filter air as it recirculates inside the cabin.

If your vehicle has a cabin air filter capable of filtering recirculated air, regularly installing a fresh HEPA or carbon-impregnated filter is the best way to improve the air quality inside your car.

Do Car Ionizers Work?

Air ionizers designed for automotive use are typically compact units that plug into a cigarette lighter socket. Instead of filtering the air, these devices emit ions, which are molecules that have a positive or negative charge instead of the normal neutral charge.

The basic idea behind a car air ionizer is that ionized particles of various allergens and odorous materials will either stick to surfaces or each other. At this point, they won't be floating in the air anymore.

Although a good air ionizer should do what it is designed to, it won't filter anything, and you may find yourself dealing with a dark coat of dust, pollen, and whatever else clinging to every surface inside your vehicle.

The other issue to look out for is that many of the small, weak ionizers that plug into a cigarette lighter are too anemic even to accomplish that much.

Do Ozone Generators Work for Smelly Cars?

Like ionizers, ozone generators don't filter the air. They generate ozone, which interacts with various odor-causing chemical substances, often rendering them odorless. For some sources of bad car smells, this works quite well.

Large ozone generators, which you can sometimes find at dealerships and independent repair shops, can generate tremendous amounts of ozone and remove many built-up odors.

Car Air Freshener and Purifier Limitations

Since every type of car air freshener and purifier comes with steep limitations, the best way to deal with car odors is to avoid creating them in the first place. If it's too late for that, it may be worth it to check into whether any of the dealers or independent shops in your area can perform (or even recommend) an ozone treatment. Substances like activated carbon, baking soda, and pumice stones can also soak up some foul odors.

Like the iconic little green trees, car air fresheners can also help with odors, although they only mask things like smoke and food smells instead of removing them, so your mileage may vary.

If you're mainly concerned about allergens, a good HEPA cabin air filter, or any cabin air filter with a sufficiently constrictive filtration media, is your best bet.

Although cabin air filters can't do anything about the air already in your car, they will prevent new allergens from entering. And since the passenger compartment isn't a sealed environment, introducing allergen-free air will eventually displace most or all of the allergen-laden air.

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