Air Purifier vs Air Conditioner: Which Should You Choose? (Australia 2026)

30 min read

An air purifier and an air conditioner do two completely different jobs, and confusing them is one of the most expensive mistakes Australian households make. An air purifier removes contaminants — particles, allergens, smoke, VOCs — from your indoor air. An air conditioner controls temperature and, depending on the type, may introduce filtered outdoor air or simply recirculate what is already inside. If your problem is poor air quality, no amount of cooling will fix it. If your problem is a 42°C day in western Sydney, no HEPA filter will save you.

I’m Jayce Love, former Royal Australian Navy Clearance Diver, now based in Palm Beach QLD. I’ve spent years measuring air quality, filtration performance, and indoor contaminants in Australian homes. This article gives you the full breakdown — what each device actually does, what it doesn’t do, what it costs to run on Australian electricity prices, and exactly how to decide which one you need (or whether you need both).

What an Air Purifier Actually Does (And What It Cannot)

An air purifier draws room air through a series of filters and returns cleaner air. That is the entire mechanism. There is no temperature change, no humidity adjustment, no ventilation from outside. It processes indoor air only.

The gold standard is a true HEPA filter rated to EN 1822:2019. Here is the efficiency hierarchy you need to know: H10 < H11 < H12 < H13 < H14. Higher number means higher particle capture efficiency. An H13 filter captures 99.97% of particles at the most penetrating particle size (MPPS) of 0.3 µm. An H14 captures 99.995%. If a product says “HEPA-style” or “HEPA-type” without specifying the EN 1822 grade, you are not getting true HEPA performance.

Most quality air purifiers also include an activated carbon layer. Carbon handles gases and volatile organic compounds (VOCs) — formaldehyde from pressed-wood furniture, benzene from paint, toluene from adhesives. HEPA handles particles. Carbon handles gases. This distinction matters because an air conditioner’s mesh filter does neither job well.

What an air purifier cannot do: cool a room, heat a room, control humidity, ventilate from outside, or remove carbon dioxide. If your indoor CO2 levels are climbing because you have sealed every window against bushfire smoke, only mechanical ventilation or opening a window (when safe) will fix that. An air purifier cleans the air you have — it does not replace it.

What an Air Conditioner Actually Does (And What It Cannot)

A split-system or ducted air conditioner moves heat energy from inside your home to outside (cooling mode) or the reverse (heating mode). It uses a refrigerant cycle and a compressor. As warm humid air passes over the cold evaporator coil, moisture condenses and drains away — this is why AC reduces indoor humidity as a byproduct of cooling.

The filtration in a standard residential AC is minimal. Most split systems ship with a washable polyester mesh filter rated somewhere between MERV 1 and MERV 4. That captures visible dust, lint, and hair. It does almost nothing for PM2.5 (bushfire smoke), pollen grains below 10 µm, mould spores, bacteria, or VOCs. Some premium units (Daikin Streamer, Mitsubishi Electric Plasma Quad) add electrostatic or plasma-based secondary filtration, but none of these match true HEPA performance, and none include activated carbon for gas-phase contaminants.

What an air conditioner cannot do: remove PM2.5 to safe levels during bushfire season, adsorb VOCs, capture ultrafine particles (PM0.1), or function as a substitute for an air purifier. If you are relying on your AC to clean the air during a smoke event in the Blue Mountains, western Sydney, or the Gold Coast hinterland, you are breathing in most of what you are trying to avoid.

Who Should Buy an Air Purifier

• You live in a bushfire-prone area (NSW south coast, Victorian high country, Adelaide Hills, Perth hills, south-east Queensland). NEPM ambient PM2.5 standards are 25 µg/m³ (24-hour average). During the 2019–2020 Black Summer, parts of Sydney exceeded 500 µg/m³. Only an H13 HEPA purifier sized to your room will bring indoor levels down to breathable.
• You or a family member has asthma, allergic rhinitis, or eczema triggered by airborne allergens. Asthma Australia’s position statement supports HEPA air purifiers as part of allergen reduction strategies. Dust mite allergen particles (Der p 1) average 10–20 µm — well within HEPA capture range.
• You live near a major road in any Australian city. Tyre wear particulate, brake dust, and diesel exhaust particles are all in the PM2.5 and PM10 range. This is a HEPA job. Suburbs like Strathfield (Sydney), Footscray (Melbourne), and South Brisbane sit within 200 metres of heavy traffic corridors.
• You have a new build or recently renovated home. Off-gassing from engineered timber flooring, cabinetry adhesives, and fresh paint can elevate indoor formaldehyde and total VOC levels for 6–12 months. A purifier with a substantial activated carbon bed (500 g minimum; 1–2 kg preferred) handles this.
• You have indoor pets. Cat and dog dander particles range from 1–20 µm. HEPA captures them. A carbon layer handles the odour component. Your AC filter does not.

Who Should Buy an Air Conditioner

• You live in a hot climate and need active cooling. If you are in Darwin (average January max 33°C, 80%+ humidity), Townsville, Cairns, Rockhampton, inland western NSW, or Perth, an air conditioner is a health necessity, not a luxury. Heat-related illness kills more Australians than any other natural hazard, according to the Bureau of Meteorology.
• You need humidity control to prevent mould. In subtropical and tropical Australia (Brisbane, Gold Coast, Sunshine Coast, Darwin, Cairns, coastal NSW north of Coffs Harbour), indoor relative humidity regularly exceeds 70%. Mould growth becomes likely above 60% RH at sustained temperatures above 20°C. A refrigerant AC actively dehumidifies.
• Your home already has good air quality and you simply need thermal comfort. If you are in a low-traffic area with no bushfire exposure, no renovations, and no allergy sufferers, an AC alone may be all you need for comfort.
• You want heating and cooling from one system. Reverse-cycle split systems provide both. Melbourne, Canberra, Hobart, and highland areas that swing from sub-zero winter mornings to 40°C+ summer afternoons benefit enormously from a single reverse-cycle unit.
• You are building or renovating and can install ducted AC with upgraded filtration. If you spec a ducted system with MERV 13+ return-air filters, you get meaningful particle filtration integrated into your HVAC. This still does not match a standalone HEPA purifier for PM2.5, but it is a significant upgrade over standard mesh.

Head-to-Head Comparison: Air Purifier vs Air Conditioner

Criterion	Air Purifier (H13 HEPA + Carbon)	Air Conditioner (Split System)	What This Means for You
Primary function	Removes airborne particles and gases	Controls temperature (heating/cooling)	They are not interchangeable. Define your problem before choosing.
PM2.5 removal	99.97% at 0.3 µm (H13 HEPA, EN 1822:2019)	Minimal — standard mesh filters rated MERV 1–4	During bushfire smoke, only a HEPA purifier protects your lungs.
VOC / gas removal	Yes — activated carbon adsorbs VOCs, formaldehyde, odours	No	New builds and renovations need a carbon-equipped purifier for off-gassing.
Cooling capacity	None (0 kW)	2.5–10 kW typical residential split	A purifier cannot cool a room. Full stop.
Humidity control	None	Reduces humidity during cooling (typically 10–20% RH drop)	For mould-prone homes in QLD, NT, and coastal NSW, AC is the humidity tool.
Power consumption	30–60 W (typical HEPA unit on medium)	900–2,500 W (compressor running)	Running a purifier 24/7 costs roughly $85–$170/year. AC costs $400–$1,200/year.
Installation	Plug in, turn on. No installation required.	Licensed electrician + refrigerant technician. Requires wall bracket, outdoor unit, drain.	Renters can use a purifier immediately. AC needs landlord approval and professional install.
Noise (typical bedroom use)	20–45 dB on low/medium	22–48 dB (indoor unit); 45–55 dB (outdoor unit)	Both are comparable indoors. AC outdoor unit noise may affect neighbours.
Ongoing filter costs	$60–$150/year (HEPA + carbon replacement)	$0–$30/year (washable mesh); $150–$300 biennial service	Purifier filters are a recurring cost. Budget for them.

The CADR Question: Why Your AC’s “Filtration” Rating Is Misleading

CADR — Clean Air Delivery Rate — is the single most important metric for comparing air cleaning devices. It measures cubic metres of clean air delivered per minute (or per hour, depending on the standard). Higher CADR means faster air cleaning. An air purifier with a CADR of 300 m³/h can cycle the air in a 25 m² bedroom (2.4 m ceiling = 60 m³) five times per hour. That means every 12 minutes, all the air in your room has passed through the HEPA filter.

Your air conditioner does not have a meaningful CADR rating. It was not designed to clean air. It was designed to move thermal energy. The mesh filter inside your split system exists to protect the evaporator coil from dust buildup — it is there for the machine’s benefit, not yours. When an AC manufacturer advertises “air purification” as a feature, they are typically referring to an ioniser, a plasma generator, or a catechin-coated filter insert. None of these have published CADR ratings that come close to a standalone HEPA purifier.

This matters most during the NSW and Victorian bushfire season (November–March). When the Air Quality Index (AQI) in your suburb exceeds 200 (hazardous), you need a device that can strip PM2.5 from your indoor air quickly and continuously. Your AC cannot do this. A correctly sized HEPA purifier can. If you are choosing between the two for air quality, there is no contest.

Running Cost Comparison: Australian Electricity Prices (2025–2026)

Electricity costs matter. The average Australian residential electricity rate is approximately $0.33/kWh as of early 2025, though this varies by state — South Australia averages higher (~$0.40/kWh), while Queensland’s regulated tariffs can be lower (~$0.28/kWh). Let’s calculate real running costs for both devices.

Air Purifier Running Cost

A typical HEPA air purifier draws 30–60 W on medium speed. Running 24 hours a day, 365 days a year:

• 45 W × 24 h × 365 days = 394 kWh/year
• At $0.33/kWh = $130/year in electricity
• Add $80–$150/year for replacement HEPA and carbon filters
• Total annual running cost: $210–$280

Air Conditioner Running Cost

A 5 kW split system (common for a 30–40 m² living area) draws approximately 1,400 W during active compressor operation. Assuming 8 hours/day for 6 months of the year (summer in Brisbane, Perth, Darwin — adjust downward for Melbourne or Hobart):

• 1,400 W × 8 h × 180 days = 2,016 kWh/year
• At $0.33/kWh = $665/year in electricity
• Add $150 biennial professional service (gas check, coil clean) = $75/year amortised
• Total annual running cost: $740

If you are in Darwin or Cairns running AC for 10+ hours a day across 8–9 months, expect $1,000–$1,500/year in electricity alone.

5-Year Total Cost Comparison

Device	Upfront Cost (AUD)	Annual Running Cost (AUD)	5-Year Total (AUD)
HEPA air purifier (mid-range, e.g. Winix, Philips)	$350–$600	$210–$280	$1,400–$2,000
Split system AC (2.5 kW — bedroom)	$1,200–$2,200 (installed)	$350–$500	$2,950–$4,700
Split system AC (5 kW — living area)	$1,800–$3,500 (installed)	$650–$900	$5,050–$8,000
Both (purifier + 2.5 kW split in bedroom)	$1,550–$2,800	$560–$780	$4,350–$6,700

The numbers speak for themselves. An air purifier is a fraction of the cost of an air conditioner — but they solve different problems. If you need both, budget for both. The combined 5-year cost is still less than most ducted AC installations alone.

Can Your AC Double as an Air Purifier? The Honest Answer

This is the question I get asked most. The short answer: no. Here is the long answer.

Standard residential split system filters (Daikin, Mitsubishi Electric, Fujitsu, Samsung — the brands most commonly installed in Australian homes) use a coarse polyester mesh. This mesh has pore sizes measured in millimetres. PM2.5 particles are measured in micrometres — roughly 1,000 times smaller than the filter openings. The filter physically cannot capture them.

Some premium models add secondary filtration technologies:

• Daikin Streamer Discharge: Uses plasma to decompose some allergens and odours on contact. No CADR published. No HEPA-equivalent particle capture.
• Mitsubishi Electric Plasma Quad Plus: Electrostatically charges particles to attract them to a collector plate. Limited independent testing. No published efficiency to EN 1822.
• Samsung Wind-Free with PM1.0 filter: Claims to filter particles down to 1.0 µm. This is better than standard mesh but still does not meet H13 HEPA standards. No CADR published.
• LG Dual Inverter with ioniser: Generates ions to cluster airborne particles. Ionisers can produce trace ozone as a byproduct. AS/NZS 3823 sets ozone emission limits for air cleaners — check the product’s compliance.

None of these match what a $400 standalone HEPA purifier does. If an AC manufacturer publishes a CADR rating and an EN 1822 filter grade for their unit, I will update this section. Until then, the evidence is clear: use a dedicated air purifier for air quality, and use your AC for temperature.

The Mould Problem: Where AC and Air Purifiers Overlap (and Don’t)

Mould is a massive issue in Australian homes, particularly in Brisbane, the Gold Coast, Sunshine Coast, Darwin, Cairns, Townsville, and the NSW North Coast. If you have lived through a La Niña summer in south-east Queensland, you know what happens: 80%+ relative humidity for weeks, mould blooming on walls, leather, and clothing.

Here is the overlap: an air purifier with H13 HEPA captures mould spores (typically 2–20 µm) from the air. This reduces your inhaled dose. But it does not address the root cause — excess moisture. A HEPA purifier captures spores floating in the air. It does not dry your walls. It does not prevent new mould growth.

An air conditioner (or dedicated dehumidifier) reduces indoor humidity, which prevents mould growth at the source. The target is below 60% RH. A refrigerant AC running in cooling mode will typically achieve this as a byproduct.

For mould-prone homes, you likely need both: AC (or dehumidifier) to control humidity and prevent growth, plus a HEPA purifier to capture spores that are already airborne. If your budget forces a choice, address humidity first — prevention beats remediation every time. Then add a purifier when budget allows.

Bushfire Smoke: The Scenario Where Only a HEPA Purifier Works

During the 2019–2020 Black Summer, PM2.5 concentrations in Canberra hit 3,508 µg/m³ — more than 140 times the NEPM 24-hour standard of 25 µg/m³. Sydney’s AQI exceeded hazardous levels for days at a stretch. People sealed their homes, turned on the AC, and assumed they were protected. They weren’t.

When you seal your home and run your AC in recirculation mode, you are recirculating smoky air through a filter that cannot capture smoke particles. PM2.5 from bushfire smoke is a complex mixture of carbon particles, polycyclic aromatic hydrocarbons (PAHs), and fine particulate matter. These particles penetrate deep into lung tissue and enter the bloodstream. The WHO classifies outdoor air pollution (including PM2.5) as a Group 1 carcinogen.

A HEPA air purifier is the single most effective indoor intervention during smoke events. Research from the University of Tasmania and CSIRO confirms that portable HEPA air purifiers significantly reduce indoor PM2.5 concentrations. The key is sizing: you need a unit with sufficient CADR for your room volume. A small desktop purifier with a CADR of 80 m³/h is not enough for a 40 m² open-plan living area — it needs to cycle the room air at least 4–5 times per hour.

Sizing formula: Room volume (m³) × 5 air changes per hour = required CADR (m³/h). For a 40 m² room with 2.4 m ceilings: 96 m³ × 5 = 480 m³/h CADR. Choose a unit rated at or above this number.

Decision Tree: 3 Questions to Choose

Running Both Together: The Correct Configuration

If you decide you need both — and most Australian households in bushfire-prone or allergy-affected areas do — here is how to set them up correctly in a bedroom or living area.

Step 1: Position the air purifier away from the AC outlet. If the AC’s airflow blows directly across the purifier’s intake, you create a short-circuit where the purifier processes the same stream of already-cooled air rather than drawing from the wider room. Place the purifier on the opposite side of the room from the AC indoor unit.

Step 2: Run the AC in recirculation mode during smoke events. Most split systems have a fresh air intake option. During bushfire smoke, close this. You want the AC processing indoor air only — cooling it and removing humidity — while the purifier strips particles and gases.

Step 3: Run the purifier continuously, not just when the AC is on. Air quality issues persist at 2 AM when you have turned off the AC. Dust mite allergen, pet dander, and VOCs do not stop at bedtime. Run the purifier on its lowest effective speed overnight. At 20–30 W, this costs roughly 7–10 cents per night in electricity.

Step 4: Clean your AC filters monthly. A clogged AC filter restricts airflow, increases energy consumption, and can become a breeding ground for mould and bacteria. Pull the mesh filters, wash them with water, dry them completely, and reinstall. This takes 10 minutes and costs nothing.

What About Portable Air Conditioners with “HEPA” Filters?

Some portable AC units sold in Australia advertise built-in HEPA filtration. Approach these with scepticism. The problem is physics: a portable AC uses a single-hose or dual-hose system that exchanges air with the outdoors. During a smoke event, a single-hose portable AC creates negative pressure inside your room, which pulls smoky outdoor air in through gaps around windows and doors. It can actually make your indoor air quality worse.

If the unit has a genuine HEPA filter, it is typically small — often 100–200 cm² of filter surface area, compared to 3,000–5,000 cm² in a dedicated air purifier. This means it clogs faster, restricts airflow sooner, and delivers a fraction of the CADR. The cooling performance also suffers when airflow is restricted.

My advice: keep the functions separate. A dedicated HEPA purifier does air cleaning better and cheaper. A dedicated split system AC does cooling better and more efficiently. Combination devices are a compromise on both fronts.

Special Considerations by Australian City

Sydney

Bushfire smoke exposure (Blue Mountains, south-west corridor), high traffic pollution (Parramatta Road, M5 tunnel vicinity), and apartment living with limited ventilation. HEPA purifier is close to mandatory for inner-west and western Sydney apartments near arterial roads. AC is already installed in most apartments.

Melbourne

Pollen capital of Australia — Melbourne’s thunderstorm asthma events (November 2016 killed 10 people) make HEPA purifiers critical during spring/summer. Mild summers in inner suburbs may not require AC, but northern and western suburbs (Werribee, Melton, Craigieburn) regularly hit 40°C+ and need cooling.

Brisbane and South-East Queensland

Humidity and mould are the dominant issues. AC for dehumidification is a priority. Bushfire smoke from the Gold Coast hinterland and Scenic Rim affects the region intermittently. HEPA purifier recommended for households with asthma or allergy sufferers.

Perth

Hot dry summers make AC non-negotiable for most of the year. Bushfire risk from the Perth Hills and south-west forests is high. Perth’s TDS-heavy water (180 mg/L CaCO3) creates mineral dust when evaporative coolers are used — another reason to prefer refrigerant AC. HEPA purifier recommended for bushfire season and households near Kwinana industrial area.

Adelaide

Extreme summer heat, dry air, and proximity to grassfire-prone areas (Adelaide Hills, Fleurieu Peninsula). Evaporative cooling works better here than in humid cities but still does not filter PM2.5. HEPA purifier recommended during fire season. Highest state electricity costs (~$0.40/kWh) make energy efficiency critical — choose an inverter AC and a low-wattage purifier.

Darwin and Tropical North

AC is a survival tool, not a comfort device. Running 10+ hours a day, 8–9 months a year. Air quality is generally good outside of controlled burn season and dry-season dust storms. A HEPA purifier is less critical here than in southern fire-prone cities but valuable for households with respiratory conditions.

Hobart and Canberra

Cold winters demand reverse-cycle heating. Summer smoke from surrounding bushland (Canberra is encircled by bushfire-prone forests) makes a HEPA purifier critical in fire season. Both cities have relatively mild summers where AC may not be needed except during heatwave events.

Ozone Concerns: Ionisers in ACs and Some Air Purifiers

Some air conditioners and air purifiers include ioniser functions. Ionisers work by electrically charging airborne particles so they clump together and settle on surfaces. The problem: the corona discharge process that generates ions can also produce ozone (O3) as a byproduct. Ozone is a respiratory irritant — it aggravates asthma and damages lung tissue at elevated concentrations.

In Australia, AS/NZS 3823 (Performance of electrical appliances — Air cleaners) sets ozone emission limits. Any air cleaning device sold in Australia should comply with this standard. If a product does not reference AS/NZS 3823 compliance, ask the manufacturer directly before purchasing.

My position: avoid ioniser-equipped devices unless the ioniser can be disabled independently. Passive HEPA + carbon filtration achieves better results without any ozone risk. If your AC has an ioniser function, turn it off. You lose nothing measurable in air quality and eliminate the ozone concern entirely.

The “Air Purifier AC” Marketing Trap

In 2024–2025, several AC brands have launched models marketed as “air purifier air conditioners.” Samsung’s Wind-Free, LG’s PuriCare, and Midea’s breezeless models all make some air cleaning claim. Here is what to look for and what to ignore:

Look for: A published CADR rating (in m³/h), a named filter standard (H13, H14, or MERV rating), and an independently tested efficiency claim (not “up to 99%” without specifying particle size).

Ignore: “Nanoe” technology (Panasonic’s marketing term for hydroxyl radicals — no published CADR), “Plasmacluster” (Sharp — limited independent verification of real-world particle removal), and any claim that uses “neutralises” or “deactivates” instead of “removes” or “captures.”

If a product captures particles, it can state a CADR. If it claims to “neutralise” them, it may be doing very little. Stick with devices that have published, verifiable performance metrics.

Energy Star and Zoned Energy Rating Labels

In Australia, air conditioners carry the Zoned Energy Rating Label (ZERL), which replaced the old star rating system in 2019. The ZERL provides separate efficiency ratings for three climate zones: hot, average, and cold. Check the zone relevant to your location — a unit efficient in Melbourne’s temperate climate may perform differently in Darwin’s tropical heat.

Air purifiers do not currently carry an Australian energy rating label. Energy consumption varies by model and speed setting. When comparing purifiers, calculate the cost per unit of clean air: annual electricity cost divided by annual CADR output. This gives you a cost-efficiency metric that lets you compare apples to apples.

Final Verdict

An air purifier and an air conditioner solve different problems. There is no “better” choice — there is only the right choice for your situation.

If your problem is airborne contaminants — bushfire smoke, allergens, pet dander, VOCs, mould spores — you need an air purifier with true H13 HEPA filtration and activated carbon. No air conditioner can do this job.

If your problem is heat, humidity, or thermal comfort, you need an air conditioner. No air purifier can cool or dehumidify a room.

If you live in an Australian city that faces both problems — and most do, at some point during the year — you need both. A mid-range HEPA purifier ($350–$600) running alongside your existing split system AC is the most cost-effective way to handle both temperature and air quality in the same space.

Start with the device that addresses your most urgent problem. For most Australians reading this in 2026, that means: if you already have an AC installed, add a HEPA purifier. If you are building new, install a reverse-cycle split system and budget $400–$600 for a standalone purifier for each bedroom. Do not rely on your AC’s built-in “air cleaning” features — they are not enough.

The next step is sizing your purifier correctly for your room. Our air purifier guide walks you through the CADR calculation, filter grades, and specific product recommendations for Australian conditions.

Frequently Asked Questions

Does an air conditioner purify the air?

No. A standard residential air conditioner uses a coarse mesh filter (MERV 1–4) that captures visible dust and lint. It cannot capture PM2.5, mould spores, pollen, pet dander, or VOCs. Some premium AC models include secondary filtration technologies (ionisers, plasma generators, electrostatic filters), but none match the performance of a standalone H13 HEPA air purifier.

Can I use an air purifier instead of an air conditioner?

No. An air purifier has zero cooling or heating capacity. It processes the air that is already in your room without changing its temperature or humidity. If you need thermal comfort, only an air conditioner (or evaporative cooler in dry climates) will work.

Should I run my air purifier and air conditioner at the same time?

Yes. Running both simultaneously is the correct approach for Australian homes that face heat and air quality issues. The AC controls temperature and humidity. The purifier removes particles and gases. Position them on opposite sides of the room to maximise air circulation and avoid short-circuiting the purifier’s intake with the AC’s direct airflow.

What is more expensive to run — an air purifier or an air conditioner?

An air conditioner costs significantly more to run. A typical HEPA purifier draws 30–60 W and costs $130–$170/year to run 24/7 at $0.33/kWh. A 5 kW split system AC draws approximately 1,400 W during compressor operation and costs $650–$900/year at moderate use. In tropical cities like Darwin, AC costs can exceed $1,500/year.

Will a HEPA air purifier help during bushfire smoke season?

Yes. A correctly sized H13 HEPA purifier is the single most effective indoor intervention during smoke events. It captures 99.97% of PM2.5 particles at 0.3 µm. Ensure the unit’s CADR is sufficient for your room — calculate room volume (m²×ceiling height) multiplied by 5 air changes per hour. Research from the University of Tasmania and CSIRO confirms significant indoor PM2.5 reductions from portable HEPA purifiers.

Do air purifiers remove mould?

An air purifier with H13 HEPA captures airborne mould spores (typically 2–20 µm), reducing your inhaled dose. However, it does not address the root cause of mould growth — excess moisture. To prevent mould, you need to reduce indoor humidity below 60% RH using an air conditioner, dehumidifier, or improved ventilation. For mould-prone homes in Brisbane, Darwin, Cairns, and coastal NSW, use both a dehumidification solution and a HEPA purifier.

Is an evaporative cooler better than an air conditioner for air quality?

No. Evaporative coolers add moisture to the air, which can increase indoor humidity and promote mould growth in already-humid climates (Brisbane, Darwin, Cairns, coastal NSW). They work effectively for cooling in dry climates (Adelaide, inland NSW, Perth) but provide no meaningful particle filtration. They also draw outdoor air in, which means they pull bushfire smoke directly into your home during fire events. Evaporative coolers are unsuitable for air quality management.

What filter grade should I look for in an air purifier?

H13 is the minimum recommended grade per EN 1822:2019. H13 captures 99.97% of particles at the most penetrating particle size of 0.3 µm. H14 (99.995%) is better but significantly more expensive and creates more airflow resistance, which can reduce CADR unless the fan motor compensates. Avoid products labelled “HEPA-style” or “HEPA-type” without an EN 1822 grade — these may have significantly lower capture efficiency.

Can I upgrade my ducted AC to filter like an air purifier?

Partially. If you have a ducted AC system, you can upgrade the return-air filter from the standard mesh to a MERV 13 or higher pleated filter. This significantly improves particle capture compared to standard mesh and can reduce PM2.5 levels in your home. However, MERV 13 (approximately 85% efficiency at 0.3–1.0 µm) still falls short of H13 HEPA (99.97% at 0.3 µm). You also need to ensure your system’s fan motor can handle the increased static pressure — consult your HVAC technician before upgrading to avoid damaging the system.

Does running my AC on “fan only” mode clean the air?

Minimally. Fan-only mode circulates indoor air through the AC’s mesh filter without engaging the compressor. It provides no cooling or dehumidification. The filtration effect is negligible because the mesh filter cannot capture fine particles. You are essentially running an expensive, low-efficiency fan. A standalone HEPA purifier on its lowest setting will deliver better air cleaning at a fraction of the energy cost.