Air Purifiers – breathe easy this spring (2024 update guide)

Air purifiers may be what you need to help you breathe easy this spring. CyberShack has tested many and shows you how to get the right one.

Our extensive testing reveals that most any air purifiers do a fine job removing enough dust and pollen; some go several steps further, removing noxious gasses like Formaldehyde, have informative readouts, and fans/heaters for multi-use.

The guide covers:

• What is air quality, and how it impacts respiratory issues?
• Sources of air quality issues in the home – cooking, flatpack, new flooring, circulation
• Why/if you need a purifier
• What are typical room sizes/layouts, and how do these affect purifiers
• The right purifier for the job (CADR, Coandă effect, UV, Ions, HEPA, other)
• Mould Control
• Remote controls, control panel readouts, sensors, Wi-Fi, and apps
• Fan, heat
• Energy Use
• Sound levels
• Maintenance, filter cost, warranty, aftersales support
• Children’s safety

What is air quality, and how it impacts respiratory issues?

The air quality index varies from state to state, and it is whether it is a commercial site like AccuWeather (select region and air quality). At a minimum, it covers Ozone (O3), Large Particulate Matter PM10 (<10 μm), Small Particulate Matter PM2.5 (<2.5 μm can be harmful) and Nitrogen Oxide (NO2 can cause respiratory issues). Asthma Australia has an iOS and Android AirSmart App that may help. Beware that most other so-called Air Quality apps are nothing more than Data-harvesters.

The information can help Identify problem days and areas but does not show internal air quality.

Sources of air quality issues in the home – cooking, flatpack, new flooring, circulation

Internal air quality has never been more important. With the proliferation of high-rise apartment living, where most air is recirculated. While Airconditioning may remove some larger particulates, it is not a purifier. The best way to improve internal air quality is to open windows, but all that does is equalise indoor and outdoor air quality. You would not want to do that on smoggy, windy, dusty or smoky days.

The leading causes of poor internal air quality are

• Cooking (without a range hood extractor)
• Smoking
• Wood or gas heaters or fireplaces (Increase carbon monoxide, nitrogen dioxide, Formaldehyde, toxic chemicals and PM2.5 small particulates)
• Flatpack furniture outgases Formaldehyde for months to years
• New synthetic carpets outgas Formaldehyde for months to years (new carpet smell)
• Mould, especially toxic black mould, can cause health issues
• If your neighbourhood has specific pollution problems, such as near industrial smoke stacks, etc.

Why/if you need a purifier

Before you scoff that your parents and grandparents never needed one, remember that air quality has only become an issue in the past few decades. You can blame part of that on climate change issues, but equally, we have more cars, trucks, high-rise, flat-pack, and air quality ‘influencers’. Hay Fever, Asthma, and respiratory issues have never been at higher levels. Hay Fever starts getting bad in Spring and is driven by potential bushfires in summer and westerly winds in Autumn.

CyberShack has reviewed many air purifiers over the years and knows that having a few around the home makes a massive difference to internal air quality. Simply put, we stake our reputation on the fact that they remove harmful stuff from the air we breathe, making it easier to sleep, work and play indoors. But they won’t increase the amount of oxygen in the room – only external ventilation can.

What are typical room sizes/layouts, and how do these affect purifiers?

If you want to tow a caravan, you don’t do it with an underpowered car. Equally vital is to calculate the room size in cubic meters (assume a 2.4m ceiling) and layout (door, windows, open space, etc.) and match an air purifier’s capacity to that.

• Small room with a door and windows – typically a 3 x 3m 21.6m3
• Medium room with a door and windows – typically 5 x 5m 60m3
• The large living area still enclosed – typically 10 x 5m 125m3
• Large living area open plan with no doors or walls to separate from the remainder of the home – typically 20 x 10m 480m3

Rule #1: Accurately measure the room and types that you want to clean.

The right purifier for the job (CADR, Coandă effect, UV, HEPA, other)

CADR – Clean Air Delivery Rate measured in cubic meters per hour (m3/hour).

Most air purifiers specify a CADR rate, which means how many cubic metres of air (1 x 1 x 1m) it can clean in a specified time. Most use per hour, but some Asian generics use per day. Just make sure the time is the same. If CADR is not specified then do not buy that brand.

How do you know a room’s cubic meterage? It is a room’s length x depth x ceiling height.

Layout: Can the room be enclosed (closed doors and windows)—a closed ecosystem? Or if it is more open (like an open-plan lounge/dining with perhaps a hallway and stairwell to other levels)—an open ecosystem?

In a closed ecosystem, the great thing is that once the air is cleaned, the job is done until more dirty air is let in (opening a window or door).

You should over-specify CADR capacity in an open ecosystem or use more air purifiers.

Now that you know the room size, you can divide CADR by it to see how many times per hour it will be cleaned.

Rule #2 – CADR indicates how often the room air will be cleaned per hour. Look for two or more times per hour and go for the highest rating you can get (except for Dyson with the Coanda effect).

Coandă effect

Some devices (like Dyson) use the Coandă effect (often called the air multiplier effect) to multiply the volume of air that leaves the purifier. While it does not directly relate to air input and filter cleaning efficiency, it increases room ventilation efficiency. It can turn over the room air faster than a purifier that sucks air in and blows it out through an upwards or forward-facing vent. It uses the POLAR index in the same way that CADR is for typical air purifiers.

Rule #3 – An oscillating fan will move the room air mass around more efficiently but really comes into its own if combined with a fan/heater/purifier using the Coandă effect .

UV, Ions and germ-killing

Some purifiers have internal UV-C lights as extra filtration.

• UV-C can inactivate many viruses and bacteria on directly irradiated surfaces with the correct exposure time. Tests on the SARS-CoV-2 virus (not COVID-19) took an exposure time of 6 seconds.
• UV-C is 200 to 280nm (see the light spectrum chart below; 254 nm is used) and is safe.
• EPA found that UV-C can reduce most bacteria by up to 99.9999% under the right conditions.
• Therapeutic Goods Administration warns that it has not approved any air purifier as a medical device, although it has approved room sterilisation systems with UV-C light.

Our take is that as long as no medical claims are made, adding UV-C light to an air purifier cannot hurt and can reduce airborne pathogens. And we doubt that any consumer-grade air purifier kills germs – it may trap some, but that is all.

The jury is out on Ions (charged particles), and this should is not a prime reason to buy an air purifier.

Rule #4 UV light is good and Ions are nice but not the main reason to buy a purifier.

Filters – HEPA, Activated Charcoal, paper and more

Typically, the air is drawn in via a fan (suction) through a fine mesh (pre-filter for larger PM10+ particles) and then a filter (can range from PM10 down to 3). It may also pass through an activated charcoal filter to remove common noxious gases.

All filters have a Particulate Matter Rating (PM) known as MERV rating, but many companies do not publish that. The higher the rating, the better the filter.

To be called HEPA, it must capture 99.97% of particles larger than .3 micrometres (or 3μm). By the way, hair is typically 70μm. Many filters are not certified HEPA grade.

As far as we know, no consumer-grade filter catches below 3um as these are more like ‘vapours’ than particles. Some may be caught attached to larger particles in the activated carbon filter.

Remember that larger particles (over PM10) will simply fall to the ground as dust, and you will still need to clean them manually.

Rule #5 – HEPA filters with a MERV rating of over 13 are best. Avoid filters that make HEPA-like claims without using the word HEPA.

Recycling old HEPA “High-Efficiency Particulate Air” filters

There are no active consumer recycling programs. We quote the Victorian Government: Place used HEPA filters in a sealed bag and dispose of in general waste. Used HEPA filters are not recyclable and contain many contaminants.

It is a global issue, as HEPA uses densely packed fibres that end up in landfills. Hopefully, we will solve this problem soon.

Do not be conned by claims that other filters are better.

• Water filters have low CADR, only capture a fraction of the particulate matter (they are more effective at PM10), do not capture noxious gases, and can lead to excessive mould growth.
• Solid-state electrolysis filters – these work on a larger industrial scale but not at consumer level.
• Passive convection-based systems using a microfurnace
• Smaller desktop or car nano-filters – a waste of money.

Formaldehyde – a 21^st-century issue

The primary sources are automotive use, pressed-wood particleboard, plywood, and fibreboard from the urea-based glue. I’m not saying the new car smell or the famous IKEA flat-pack kills us, but you inhale Formaldehyde. It is also in permanent-press fabrics, paper product coatings, disposable nappies, and insulation materials. In addition, Formaldehyde is also used as an industrial fungicide, germicide, and disinfectant.

It is a 21^st-century problem because we live in a flat-pack world, in high–rise apartments with recirculated air conditioning, and don’t open windows. If you live in an older home with wide-open windows, you should not have an issue until you install carpet, compressed hardwood, or faux wood flooring. On average, Formaldehyde is in the air at around 0.03 ppm (approximately 1/3^rd of the Cancer.gov dangerous level).

Dyson has invented two patented technologies.

First is a ‘catalytic converter’ (a catalyst that causes something to happen without being used in the process) that breaks Formaldehyde down into tiny amounts of water (H2O) and carbon dioxide (CO2). It lasts a lifetime because it regenerates during the process.

Second, a solid-state detector to measure mg/m3 – damned hard as formaldehyde gas is 500 times smaller than particles trapped in its HEPA and activated charcoal filters.

CyberShack understands that no other consumer-grade air purifier can remove Formaldehyde (a gas, not a particle) via HEPA or Activated charcoal filters—any claims otherwise are pure BS.

We quote: No filter-based consumer air purifier can remove Formaldehyde. Filters only trap particles down to 3.0um. Carbon filters can trap many chemical gasses (VOCs) but cannot retain Formaldehyde. You must destroy it—break it down into its component elements.

Rule #6 – Formaldehyde is an issue for apartment dwellers and those living in relatively closed environments. For the rest, it is a nice thing to have.

Mould control

Air purifiers do not kill mould but may trap some mould spores and reduce the spread. You need a dehumidifier (which may be part of an air purifier). These trap water in the air and fill an internal tank that needs emptying when full. An Air conditioner is usually far more efficient at dehumidifying and often has a specific setting to dry the air. Heaters will not kill mould.

Users often comment that dehumidifiers dry their skin, so use a moisturiser.

Rule #7 – Mould control is only if the air purifier has a dehumidifier, and you have a mould problem.

Remote controls, control panel readouts, sensors, Wi-Fi and apps

Most air purifiers sit in a corner and do the job. To be effective, they should be left on 24×7. While that means more frequent filter replacement, it also means consistently cleaner air.

A remote control is unnecessary unless it is easier to change purifier settings or measure air quality away from the purifier. The exception is Dyson’s fan/heater purifiers, which need a remote control to operate fan speed, oscillation, and readouts.

Readouts range from Coloured LEDs/rings/bars to detailed Ozone, COS, VOC, and more. A helpful feature is the ability to dim any LED readouts at night. Remember that this is more for interest than practicality and is not the reason to buy one brand over another.

Rule#8 – Don’t be distracted by the frippery unless it is vital to the air purifiers operation

Remote air quality sensors

I like the concept of remote air quality sensors as they can be placed away from the purifier and give a separate reading. But again, this is really of little use as the air purifier will eventually clean the whole room.

Rule #9 – remote air sensors are nice but don’t really do that much more.

Wi-Fi and Apps

Wi-Fi and Apps are more for interest and perhaps the ability to control a Smarthome remotely. If there is an App, it usually means privacy issues, and I don’t trust any company with my information. Some generic Asian purifiers have been found to send data to China and could be a weak point in home network security.

Rule #10 – If it needs an App to work, forget it

Fan, heat

The majority of air purifiers are just that. Air comes in, cleaned, and shot out the top. Dyson has a variety of Fan/heat air purifiers that offer more utility at higher prices. They replace stand-alone heaters and fans and do just as good a job. Remember, Dyson was the first to use the Coandă effect and moves up to 10x the amount of air around the room.

Rule #11 – Buying one multi-purpose device is the way to go.

Energy Use

While most use negligible energy (kilowatt hours), they are only effective if left on 24×7. Those with an Automatic setting will be the most power-efficient.

Rule #12 – most will be energy efficient as straight purifiers. Combo units with heaters will draw more power when heating.

Sound levels

Depending on fan speed, most will range from low 30 to 70dB. 30-40dB at a mid-range speed is acceptable in the bedroom. If it is in a lounge area, then 50-60dB is acceptable.

Rule #13 – Quieter the better but expect some noise at full fan speed.

Maintenance, filter cost, warranty, aftersales support

The biggest complaint about generic and no-name air purifiers is that replacement filters become unavailable, rendering the device useless. Many have no after-sales support.

The second biggest complaint is the cost of replacement filters. Most good filters have a 4000-hour life (365 days x 24 hours = 8,760 hours), while cheaper air purifiers have a 1000-2000-hour life.

Remember that you buy an air purifier to clean the air to help you breathe better, and filter replacement costs go with the territory.

For example, Dyson HEPA and Activated Carbon filters cost $89/99, and while no lifespan is published, the machine measures their efficiency and advises when to replace them. Samsung filters range from $79 to $199, and the machine advises based on hours used.

Rule #14 – If ongoing cost is an issue, look at the filter replacement costs and life – you may be surprised.

Children’s safety

Toddlers and children can use the filter to support them when learning to walk. We test with a 10kg weight to see if the device tips and the purifier’s weight will hurt the child.

Rule #15 – Stability, base size, castors or sliders, fan blade style etc., must be considered.

CyberShack’s view – Air purifiers – many traps for the unwary

The need for cleaner air is a 21st-century problem. Air purifiers are now more of a necessity. The easiest way to use this guide is to select the issues that matter to you and use them as a checklist.

We did not mention purchase price as that is what you pay; value is what you get. All we can suggest is that you set a budget and get the best you can for that.

What to buy – there are over 70 from major retailers

We did not review any air purifiers in 2024 as we were inundated with other device categories. But based on what we have learned over time, here are our recommendations. (Prices correct at 1/11/24 based on Harvey Norman and other stockists). You can’t go wrong with these brands.

• Breville: The traditional barrel style costs $299 to $599, and replacement filters cost $65 to $99, depending on CADR.
• Delonghi: Air Dry Humidifier is $639
• Dyson: Bladeless ranges from $799 to $1149 (Formaldehyde). A typical filter costs $89-$99
• Ionmax: UV-C ranges from $249 to $999—highly recommended. Filters range from $50 to $349.
• Philips: The traditional barrel style costs $396 to $549, and filters cost $59 to $149. Philips is well made and has a 90-day money-back guarantee.
• Samsung—Bespoke Cubes range from $1299 to $1699, barrel styles from $699 to $999, and filters from $79 to $199.
• TruSens: UV-C from $199 to $599. Filters from $59 to $109.

We cannot recommend home brands bought from stores such as Kmart or Big W or online marketplaces like Kogan/DickSMith/MightyApe/MattBlatt, Catch, MyDeal, Temu, Shein or eBay/Amazon as replacement filters are only available for a very short time and must be replaced at least annually.

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