Air scrubber vs Air Purifier – What’s the Difference?

The coronavirus has made staying indoors a norm and while one might believe indoor air quality is better than the air out there, it’s no different. If anything, the indoor air quality might be worse due to the lack of proper ventilation and conditions that favor microbial growth. This is further supported by EPA’s Office of Research and Development, which found indoor air to be 2-5 times more polluted than outdoor air.

Having an air-cleaning device like an air purifier or an air scrubber is a necessity in these testing times, as the right one will not only take care of the particulate matter in the air but will also handle noxious odors and chemicals. 

If you’re confused about the type of air purification device your space needs, you’re in the right place. This article will guide you through different air purification systems so you can make the right choice.

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What is an Air Scrubber?

An air scrubber is an innovative device that produces negative ions that attach themselves to contaminants making them too heavy to roam about in the air. Air scrubbers can be attached to existing HVAC ducts and will add purification functionality to your home ventilation system. According to the Federal Remediation Technologies Roundtable, both wet scrubbing and dry scrubbing can significantly bring down indoor air pollutants.

How do Air Scrubbers Work?

Air scrubbers work by passing the incoming air through fine tubes that have a UV light, which degenerates the microbial DNA and also passes it through a catalytic process that releases negative ions into the air. The negative ions attach themselves to positively charged air contaminants that are too tiny to be captured by a normal physical filter.

This process makes the airborne pollutants too heavy to float in the air and you might see an increase in the dust when you use an air scrubber for the first time. But as this dust is removed, the buildup of pollutants will be significantly reduced.

The dust will normally be pulled into the HVAC system as the fan circulates the indoor air and will eventually be filtered out thanks to a mix of the carbon filters and HEPA filters that are usually found in infiltration systems.

Wet Scrubbers vs. Dry Scrubbers

At an industrial level, the amount of pollutants and the incoming flue air volume is too large to be handled by thin tubing and UV light. Instead, a reagent is used that neutralizes airborne contaminants by reacting or attaching to them.

A wet air scrubber sprays a liquid reagent onto the incoming flue air, whereas a dry air scrubber uses dry reagents. Both processes have a similar outcome: the harmful particles are either neutralized or changed into a different non-toxic substance.

Wet scrubbers produce a sludge that has to be treated separately while dry air scrubbing is relatively cleaner as it doesn’t produce waste that has separate handling requirements.

What is an Air Purifier?

An air purifier or an air cleaner filters the contaminants from the air by using a mix of air filters that trap dust particles, dust mites, mold spores, pet dander, and can also neutralize dangerous gases. Budget air purifiers feature 2-stage filtration or a 3-stage filtration system, while the more advanced ones can have as many as 5 stages. According to studies, air purifiers can help bring down asthma attack frequency and ease medication burdens by reducing the number of allergens in the air. 

Unlike an air scrubber, the whole air filtration process takes place inside the air purifier. While most air purifiers use mechanical filtration, some can use electrostatic charge and negative ion filtration just like air scrubbers.

For advanced odor control that escapes the mechanical filtration, there is a carbon filter or an activated carbon mesh filter that neutralizes organic compounds (VOCs) and other unwanted odors.

How do Air Purifiers Work?

Air purifiers pass the air through a series of filters, these include:


A pre-filter captures large particles like hair, pet fur, and dust before the air can make its way towards other, more expensive filters. Some manufacturers use a nylon mesh pre-filter, while others use a different composition. These can usually be vacuumed or even washed depending on the type.

HEPA Filter (High Efficiency Particulate Air Filter)

A HEPA filter, as described by the United States Environmental Protection Agency (EPA), can remove 99.97% of airborne particles, even with a tiny size of 0.3 microns (µm). HEPA filters have a MERV rating based on their ability to capture particles between the sizes of 0.3 and 10 microns. A MERV 1-4 HEPA filter can remove particles with a size of 3-10 microns with 20% efficiency whereas a MERV 16 can filter 0.3-1 micron size particles with an efficiency of 99.97%.

HEPA filters are usually placed after the pre-filter or can be sandwiched between different filters.

Carbon/Activated Carbon Filter

A carbon filter or an activated carbon filter neutralizes organic compounds and takes care of household odors, chemical odors, and even pet or cooking odors. These filters can come in different variations, some manufacturers use a honeycomb design on their carbon filters while others use a simple carbon sheet. 

While carbon filters are great for odors and are even used in gas masks, they have a problem of off-gassing. The filter can release some of the absorbed gaseous contaminants back into the air.

Additional Stages

Some air purifiers add additional stages of filtration apart from the above-mentioned filters. These may include a UV-C light chamber and/or a negative ion filtration stage that air scrubbers employ.

Air Scrubber vs Air Purifier

While air scrubbers and air purifiers present a different air purification solution, some air purifiers add an extra stage of filtration that uses the same air purification technology as an air scrubber. 

What is the difference between an air scrubber and an air purifier?

Air purifiers primarily use mechanical filtration. The air has to enter the body of the air purifier and is passed through various filters to filter out the contaminants. On the other hand, air scrubbers release negative ions into the air that make their way towards air pollutants and latch onto them. This makes the air pollutants too heavy to stay airborne.  

Air scrubbers only rely on the power of negative ions and UV filtration, the mechanical filtration is left to the HVAC filters. As mentioned above, some manufacturers are now coupling the air scrubbers technology into air purifiers to provide a 360˚ solution.

The negative ion air purification can bring significant advantages as highlighted by studies. For indoor space, air scrubbers might be overkill as they are generally meant for commercial use. An air purifier on the other hand is usually a portable unit that can offer a simple air purification solution. 

CharacteristicAir ScrubberAir Purifier
Removes Dust
Removes VOCsOnly some
Power Consumption10-20 Watts 5-100 Watts
Operation CostLowHigh
Leaves Behind ResidueYesNo
Effectiveness against MoldLimited (requires HEPA filter)Highly Effective
Space Coverage>50 sq. ft.50-1500 sq. ft.


So, Which Air Cleaner is Right for You?

As both air purifiers and air scrubbers employ ionization to cleanse the indoor air, both are viable solutions for your air quality issues. They can both eliminate pollutants with an efficiency of 99%.

The air scrubber adds an extra stage as the purification is happening outside the device. This produces more cleaning requirements as dirt buildup can be an issue in the initial few weeks of usage.

The air purifier handles this issue as purification and filtration are happening inside the air purifier but adds to the cost as the filters will need to be changed periodically. The better the filtration rating of a filter, the more expensive it is to replace it.

Air scrubbers do not require maintenance and can also clean surfaces, something the air purifier cannot do. The negative ions can latch onto surface contaminants too, making it easier to keep the whole space spotlessly clean. If your space has mold infestations and you need a 360-degree solution then an air scrubber is the best way forward.

Conversely, if you want to move the device around a lot and need a quick solution to air quality issues then an air purifier will be a better choice as it can cleanse the indoor air several times an hour and will ensure you get an allergen-free breathable air in no time.