Are air scrubbers better than air purifiers?

This article discusses the difference between an air scrubber and an air purifier. We use the distinctions between them to determine which device is better when it comes to maintaining the indoor air quality.

What are air scrubbers and how do they work?

The term ‘scrubber’ refers to a liquid that is used to remove contaminants from the air. In other words, the contaminant is removed from the air. 

A wet scrubber is a form of air cleaner in which a liquid is sprayed into the air to clean it. Water is frequently used as the cleaning liquid in wet scrubbers. 

The other form of air scrubber is the dry scrubber, which cleans the air with a cloth or mechanical filter. A HEPA or carbon filter, for example.

The most common method for removing gases is to use an air scrubber. An air scrubber was initially used to remove carbon dioxide from the air, and it is still a common air filtering device in submarines.

The air scrubber continually creates negative ions as air passes through your ducting system. Those negative ions are dispatched on a mission to locate and return impurities floating in your air that are too tiny to be collected by your standard air filter.

An Air Scrubber uses microscopic metal tubes to produce negative ions. The tubes, which are formed in the shape of a honeycomb and have a specific coating, are placed in a honeycomb pattern.

The air goes through the tubes before passing through a segment with ultraviolet (or UV) radiation. Negative ions are formed as a result, and they are dispatched on their way to purify your air.

When negative ions are present in your home’s air, they seek out positively charged particles such as germs, pollen, and other allergies.

When negative ions and positive particles come together, they form bigger, heavier particles that can’t float in the air. They instead fall to the ground or land on surfaces.

When the fan on your air handler turns on, it pulls the freshly produced, bigger dirt particles through your ducting system, eventually resting on and clinging to your air filter.

What is an air purifier and why do we need it?

Air purifiers are devices which, as the name suggests, clean the ambient air. There are mainly two types of air purifiers, namely:

  • High efficiency particulate air (HEPA) filters
  • Air ionisers

These air purifiers can have additional components, such as a UV light chamber, activated charcoal filter, and so on, which are mainly designed for widening the spectrum of the device’s efficacy against various pollutants.

Many people wonder whether an air purifier is the right investment. However, in the current scenario, where air pollution is prevalent and worsening with each passing day, especially in urban areas, air purifiers are very vital.

Air pollution is the presence of undesired substances in the form of solids, liquids, or gases, which are suspended in the ambient air, and can adversely affect human health.

These pollutants can be especially harmful if present in the indoor environment. The average human being spends more than 90% of their total lives in an indoor environment, with more than 80% of it inside a building.

Indoor air, just like outdoor air, is susceptible to pollution. Indoor air can get polluted when pollution from outdoors infiltrates through openings such as doors, windows, cracks, seeps, etc.

Indoor air can also get polluted from indoor sources, which can arise from things such as furniture, household items, solvents and dyes, spores from mold and mildew, combustion of fuels and firewood, and hobbies/activities such as smoking, etc.

The pollutants generated from these sources have been shown to adversely affect human health, and continuous exposure to elevated concentrations can cause many serious issues, such as cancers, respiratory and cardiovascular disorders, and even death.

This is where air purifiers come in. They help to get rid of the pollutants in the indoor air, thereby keeping it clean and fit to breathe.

How air purifiers work at home

As discussed before, there are two types of air purifiers, namely:

  • Air purifiers with HEPA filters
  • Air ionisers

We shall discuss these in more detail.

Air purifiers with HEPA filters

These air purifiers are also known as passive air purifiers. They simply pull in air from the indoor air, pass it through the filter, and release the purified air back in the enclosure.

The HEPA filters are very popular nowadays, as they have an efficiency greater than 99% against particles that are equal to or greater than 0.3 microns in diameter.

Air ionisers

Air ionisers are also known as active air purifiers. They release negatively charged ions into the ambient air. These negatively charged ions attract pollutants that have a positive charge and combine with them.

Once they are combined, the pollutant particle becomes too heavy to stay suspended in the ambient air. Therefore, they get deposited on surfaces.

Sometimes, an air ioniser can also be an additional component in an air purifier which has a HEPA filter.

Which one is better?

While both are good in their own ways, air purifiers with HEPA filters are by far a better option than air ionisers.

The main reason for this is that ionisers simply remove particles from the air, which get deposited on floors, surface of items, and ceilings.

These particles can cause allergies, and need to be cleaned and removed manually. Furthermore, ionisers produce a considerable amount of ozone in their working, when compared to HEPA air purifiers.

Ozone is a highly reactive gaseous molecule which is naturally present in the upper layers of the atmosphere, where it absorbs the sun’s damaging ultraviolet radiation.

When present in the lower levels of the atmosphere, however, it acts as a pollutant, and can have serious adverse effects on human health, which also includes afflictions related to the cardiovascular and respiratory systems.

Ozone acts as an irritant, due to its pungent odor. It can cause wheezing, irritation in the nose and throat, runny nose, watery eyes, difficulty in breathing, and so on.

Additionally, ozone can also worsen the condition of people who are suffering from diseases such as asthma, emphysema, and bronchitis.

Bottom line – air scrubbers vs. air purifiers

Both air purifiers and air scrubbers use the chemistry of ionization to clean the air. This means that both devices will deep-clean your air, eliminating up to 99% of airborne particles. 

If you are seeking to purify the air in your home, both choices will get you there. The advantage to an air purifier is that the cleansing process happens within the device itself. 

Pure air leaves the device, delivering clean, fresh air to your space immediately after installation. However, replacing the high-efficiency MERV filter on an air purifier would need frequent maintenance. 

Filters with a higher MERV rating, such as those found in air purifiers, will cost more than the more typical air filters found in air handlers.

The air scrubber, on the other hand, has no components that need to be replaced on a regular basis — it’s set and forget. While the fact that the purifying job is done in your environment rather than within the device itself may seem unsettling, the air scrubber has a significant benefit in that the negative ions will cling to particles on surfaces in your house such as worktops, doorknobs, and light switches. 

Only airborne particles can be cleaned by an air purifier. An air scrubber is the way to go if you want clean air as well as clean surfaces.


Air scrubbers are devices that although are more expensive in terms of an air purifier, they are more effective in terms of cleaning the indoor air.

Air purifiers can only get rid of the particulate matter associated with indoor air, while the mechanism through which air scrubbers work also help to get rid of odors and gaseous pollutants with ease.

Furthermore, although air purifiers are relatively cheaper, they require a higher frequency of maintenance and replacement of air filters, which can be quite expensive.

On the other hand, air scrubbers require a one-time installation, and continue to work for a longer period of time, before the need to change the filters arise.


Are air scrubbers effective against coronavirus?

Air scrubbers are not completely effective against the virus that causes COVID-19. Coronavirus transmits in various ways, which are:

1. Direct or indirect contact: 

The virus can be transferred by contacting an infected person’s mouth, nose, or eyes after touching an infected object or surface. 

For this type of transmission, air scrubbers are ineffective. For this type of transmission, good hygiene, which is a sort of source control, is beneficial.

2. Droplet spray in short range transmission:

When an infected individual exhales, the virus can spread through respiratory droplets (breathes, coughs, sneezes, sings, yells, or talks). 

These droplets are often bigger (>5 microns in diameter) and fall out of the air in seconds to minutes. For this type of transmission, air scrubbers are ineffective. 

This type of transmission may be prevented through social distance and masks, as well as customised filtration pressure differentials, which involves creating a negative air pressure in a certain area in order to keep all pollutants from spreading.

3. Aerosol in long-range transmission (airborne transmission):

When an infected individual exhales, little respiratory droplets (less than 5 microns in diameter) are produced. Smaller, aerosolized viruses can linger in the air for a long time and move long distances on air currents. 

For this type of transmission, air scrubbers and customised filtration pressure differentials might be beneficial.

How long should you run an air scrubber?

An air scrubber should remain in the environment for 24 to 48 hours to properly clean the air, according to industry guidelines. 

These air exchange machines typically do 4 to 6 air exchanges each hour, assisting in the filtration and cleaning of the airspace.

Where do you put an air purifier?

The best suited place for installing your air purifier is on the wall, at a height of about three to five feet above the ground, in a room which receives the highest airflow rate with respect to the other rooms.

Furthermore, care should be taken when placing the air purifier. It is necessary to ensure that there is no obstacle in its path, and it is away from other electronic devices at least by a distance of 5 feet.

However, due to certain circumstances, it would not be ideal to mount the air purifier unit on the wall. However, there are many models available in the market which are designed based on the user’s preference to place the air purifier.

Lastly, it is important to buy an air purifier which has a coverage area suited to the requirements of the user.


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