Clean Air Blog

Smoke can affect indoor air quality in more situations than many people realise. In New Zealand, this often isn’t just large bushfires. It also includes winter woodburner smoke, smoke from neighbours’ fires, outdoor burn-offs, and long‑range smoke drifting in from major fire events. When smoke enters your home, it brings very fine particles that are easy to breathe deep into your lungs and difficult to avoid without some form of filtration. Air purifiers can help reduce indoor smoke, but it’s important to understand what kind of smoke we’re talking about, how purifiers help, and what to look for when choosing one. This guide explains: How smoke affects indoor air quality Practical steps to reduce smoke exposure at home How to check the air quality in NZ How air purifiers help with smoke What to look for in an air purifier for smoke Quick Summary: Air Purifiers for Smoke Smoke from fires and woodburners contains very fine particles (PM2.5) Smoke can enter homes even when doors and windows are closed HEPA air purifiers can reduce indoor smoke particles Carbon filters help with smoke smell, not particle removal The purifier needs enough airflow (CADR) for the room size to be effective Table of contents 1. Why Smoke Is Harmful, Understanding PM2.5 2. Keeping Smoke Out of Your Home 3. How Air Purifiers Help with Smoke & PM2.5 4. Choosing the Right Air Purifier for Smoke 5. Using an Air Purifier During Smoky Conditions 6. Checking Air Quality in NZ 1. Why Smoke Is Harmful, Understanding PM2.5 Smoke contains a mix of gases and particles, but the main concern is PM2.5 - tiny particles small enough to enter deep into the lungs and even the bloodstream. PM2.5 can: Irritate the throat, nose and eyes Worsen asthma and allergies Aggravate heart and lung conditions Cause headaches and poor sleep Build up indoors unless removed In NZ, winter woodburners regularly cause PM2.5 spikes, especially on still nights that trap smoke near the ground. Large events like the Port Hills Fire or Australian bushfire drift can cause very high short-term levels as well. If you can see or smell smoke, assume PM2.5 levels are high 2. Keeping Smoke Out of Your Home Health New Zealand’s general advice during smoke events is simple: Stay indoors if possible Close all windows and doors Reduce outdoor air getting inside Here’s how to put that into practice at home: a. Close and seal your home Shut windows and doors Use curtains, door snakes, or towels to block gaps Avoid creating drafts b. Turn off ventilation systems that pull in outdoor air Systems such as HRV or positive-pressure ventilation often draw outside air in, and most cannot effectively filter out PM2.5. Turn these off during smoke events unless your system has a HEPA intake filter. Heat pumps are fine, they recirculate indoor air and don't draw in smoke. c. Reduce indoor PM2.5 contributors These activities make indoor smoke levels worse: Frying or grilling Burning candles or incense Vacuuming (which stirs up dust) Smoking indoors Keep indoor air as stable as possible. d. Create a Cleaner Air Space Indoors Pick a room (often a bedroom or living area) and keep the air in there as clean as possible by: Keeping windows and doors shut Reducing drafts Avoiding dust-creating activities Running a HEPA purifier This room becomes your safest indoor space during heavy smoke. 3. How Air Purifiers Help with Smoke & PM2.5 Air purifiers clean air by pulling it through filters that trap pollutants as air circulates around a room. HEPA filters remove smoke particles HEPA filters are very effective at capturing fine particles like smoke. When air passes through a HEPA filter, virtually all smoke particles are removed in a single pass. The main limitation isn’t filtration efficiency, it’s simply how much air the purifier can move through the filter over time. This applies whether the smoke source is a nearby woodburner, winter haze, or a larger fire event. Carbon filters help with smell & chemicals, not particles Activated carbon filters don’t remove smoke particles, but they can help reduce smoke odour and chemical gases that come with combustion. Carbon improves comfort, but it doesn’t replace HEPA filtration. If a purifier doesn’t contain meaningful carbon (measured in grams of pellets), it won’t do much for smoke smells 4. Choosing the Right Air Purifier for Smoke Not all air purifiers are equally effective for smoke. One of the most common issues is simply not having enough airflow. The best filter in the world is useless if air doesn't go through it. Why CADR matters CADR (Clean Air Delivery Rate) describes how much clean air a purifier can deliver per hour. Smoke events often require more airflow than everyday dust or pollen, because outdoor smoke keeps leaking back in. As a practical guide: Aim for a minimum of 3 air changes per hour (ACH) from purification alone Larger rooms or very smoky conditions benefit from more than this If the purifier is too weak, it will still work, just more slowly, and it may need to run on higher (and louder) speeds. In heavier smoke, it may also struggle to keep PM2.5 levels in healthy ranges. Manufacturer “room size” claims can be misleading, so focus on CADR rather than marketing numbers to avoid under‑sizing What to prioritise for smoke If you're looking for a purifier to help with smoke, focus on: HEPA filtration (for harmful particles) Enough airflow (CADR) for the room size Optional carbon if smoke smell is a concern No ionisers or ozone‑producing features Smart Air: Proven use during smoke events California wildfire response 800+ Smart Air Blast purifiers deployed by local air quality management districts Used to create clean air spaces in libraries, community buildings, and temporary shelters Designed to operate continuously during days or weeks of heavy smoke Why these purifiers are chosen Very high airflow → clears smoke particles quickly True HEPA filtration → removes the vast majority of smoke particles per pass No ionisers or ozone → safe for extended indoor use View Smart Air Blast Mk II 5. Using an Air Purifier During Smoky Conditions During winter smoke or fire events: Run the purifier continuously, not just for short bursts Use higher speeds during peak smoke, then lower speeds once air improves Keep doors and windows closed when outdoor air quality is poor Place purifiers in the rooms you spend the most time in 6. Checking Air Quality in NZ Smoke levels can shift quickly, whether from woodburners, fires, or drifting smoke. Checking air quality helps you know when to seal the home and when to ventilate. One challenge is that air-quality monitoring in NZ is limited. Even with community networks like PurpleAir and AirGradient, many towns and rural areas have no sensors at all. Official monitoring is even more restricted. These are the most useful tools: a. IQAir (best real-time map - aggregates multiple sources) IQAir combines: Official regional council monitors PurpleAir community sensors AirGradient sensors Other public/global data sources It’s often the most complete real-time view in NZ, especially if your town has no official station. View IQ Air Map b. LAWA Air Quality (official NZ data + long-term trends) LAWA provides verified PM2.5 and PM10 readings where regional councils have monitors, plus: Recent hourly data Long-term and seasonal trends Annual exceedances of NZ standards Great for understanding typical patterns, coverage varies. View LAWA Map c. Indoor air-quality monitors Outdoor data doesn’t always reflect what’s happening inside your home. An indoor PM2.5 monitor helps you see: How much smoke is leaking in When levels rise How effective your purifier is This is especially useful in older NZ homes that naturally draw in outdoor air. Check out our Indoor Air Quality Monitors The takeaway for dealing with smoke: Smoke from woodburners and fires contains very fine particles that can build up indoors. HEPA filters remove most of these particles each time air passes through, but the key limitation is CADR - how much air the purifier can clean.A correctly sized purifier, run consistently, can noticeably reduce smoke indoors. In heavier smoke, smaller units may struggle to keep PM2.5 at healthy levels, which is why sizing matters. Looking to reduce smoke indoors? Explore HEPA air purifiers designed to effectively tackle smoke. Quiet enough for bedrooms, powerful enough for living spaces, and free from unnecessary gimmicks. See Product See Product See Product See Product Do air purifiers help with woodburner smoke from neighbours? Yes. While they can’t stop smoke entering your home, they can reduce the amount of fine smoke particles once inside. Is carbon necessary for smoke? Carbon helps with smell and gases, but HEPA is the priority for health‑relevant smoke particles. Should I run a purifier overnight in winter? Yes, especially since smoke levels in colder areas tend to remain elevated overnight. Bedrooms often benefit the most. Can one purifier cover my whole house? Usually not. It’s more effective to place purifiers in key rooms rather than trying to cover the entire home with one unit. Relevant Articles: The Best Air Purifiers in New Zealand: 2025 Comparison Read more Unmasking the Winter Air Quality Issue in New Zealand Read more What features matter when choosing an Air Purifier (NZ Guide) Read more

Odours and chemical smells are one of the most common reasons people start looking into air purifiers. Whether it’s cooking smells, pet odours, smoke, or off-gassing from everyday products. Air purifiers can help reduce odours and VOCs, but only when they’re used correctly and paired with the right type of filter. They’re also not a silver bullet, ventilation still plays a critical role. This guide explains: What causes odours and VOCs indoors How air purifiers help (and where they don’t) What actually matters in a carbon filter How to set realistic expectations Quick Summary: Air Purifiers and Odours Odours are caused by gases (VOCs), not particles HEPA filters alone do not remove odours Activated carbon is required for odour and VOC reduction More carbon = better performance (measured by weight) Ventilation is still the most effective way to clear smells Table of contents 1. What causes odours and VOCs indoors? 2. HEPA vs carbon: Why odours are different 3. How carbon filters actually work 4. Why "carbon filter included" often means very little 5. Realistic expectations: what air purifiers can (and can’t) do 6. Odours & VOCs in specific situations 7. How our purifiers handle odours and VOCs 8. Carbon filter lifespan: a common question 1. What causes odours and VOCs indoors? Most odours indoors come from volatile organic compounds (VOCs). These are gases released by everyday activities and materials. Common sources include: Cooking (especially frying, oils, spices) Pet odours and litter trays Smoke (fires, wood burners, tobacco) Cleaning products and sprays Paints, glues, sealants, and new furniture Workshops, 3D printing, resin, and hobby spaces Because VOCs are gases, they behave very differently to dust or pollen. This is why filter choice matters so much. 2. HEPA vs carbon: Why odours are different This is a key point that’s often misunderstood. HEPA filters capture particles like dust, pollen, mould spores, and PM2.5. They are excellent at this, but they do not remove gases or smells. To reduce odours and VOCs, you need activated carbon filtration. If a purifier doesn’t contain meaningful amounts of activated carbon, it won’t do much for odours. Regardless of how good other filter(s) are. 3. How carbon filters actually work Activated carbon works by adsorbing gases onto its surface. The effectiveness depends on three main factors: 1. Carbon Form Carbon pellets or granules are far more effective than thin carbon-coated meshes. 2. Carbon Quantity More carbon means more surface area and longer‑lasting odour reduction. This is why carbon weight (grams or kilograms) matters. 3. Airflow (CADR) A purifier needs sufficient airflow to pull odours and VOCs from around the room and pass them through the carbon filter. If airflow is too weak, much of the polluted air simply never reaches the filter. This is a common issue with small or low‑powered purifiers marketed for odours. Even if they contain carbon, insufficient airflow means odours don’t get a proper chance to be treated. 4. Why "carbon filter included" often means very little Many air purifiers advertise that they include a “carbon filter” or “VOC layer”, but in practice this can be: A very thin carbon sheet Only a small amount of carbon Designed more for marketing than performance These filters may slightly reduce smells at first, but they saturate quickly and provide limited ongoing benefit. 5. Realistic expectations: what air purifiers can (and can’t) do Air purifiers with proper carbon filtration can: Reduce everyday odours over time Lower background VOC levels Improve perceived air freshness They won't: Instantly remove strong smells Eliminate odours embedded in walls, carpets, or furniture Replace ventilation For persistent or strong odours, ventilation is still the most effective solution. That means opening windows and doors, or using mechanical systems like HRV, extraction fans and kitchen rangehoods. 6. Odours & VOCs in specific situations Cooking Smells Carbon filters can help reduce lingering smells, but kitchen extraction and ventilation remain important. Pet Odours Carbon helps with odours; HEPA helps with dander and allergens. To learn more, check out our article on purifiers and pets Smoke Smells Air purifiers can help with airborne smoke particles (HEPA filtration) and some smells. However smoke, especially from cigarettes often permeates furnishings and building materials. This means a purifier won't provide as much help when it comes to removing smells from a long term smoker house. Workshops, resin, and 3D printing Carbon filtration becomes much more important here. Many people underestimate how much carbon is needed for chemical vapours. For ongoing hobby or workshop use, larger carbon amounts and good ventilation are strongly recommended. New home smells and renovations If you’re dealing with new home smells, renovations, paint, or off‑gassing materials, we cover that in more detail in our dedicated article on new home smells and VOCs. VOCs in New Homes & Renovations Guide 7. How our purifiers handle odours and VOCs We focus on real, measurable carbon filtration, paired with enough airflow to actually circulate room air. Smart Air Sqair Carbon filter included as standard 140g of carbon pellets per filter Additional carbon filters can replace the HEPA for heavier VOC use Add up to 5 extra carbon filters in total for increased odour reduction View Smart Air Sqair Smart Air SA600 2x Carbon filters included as standard 170g carbon pellets per filter Can add 2 additional carbon filters for higher VOC loads Quiet enough to run continuously View Smart Air SA600 Smart Air Blast Mini Mk II Optional carbon filter 550g carbon pellets per filter Quiet enough to run continuously View Smart Air Blast Mini Mk II Smart Air Blast Mk II Optional carbon filter 900g carbon pellets per filter Quiet enough to run continuously View Smart Air Blast Mk II 8. Carbon filter lifespan: a common question Carbon filter lifespan is very difficult to estimate, as it can vary massively depending on: Type and concentration of VOCs Room size and airflow How often the purifier is running In light odour environments, carbon filters may last many months. In heavier VOC settings (painting, resin, smoke), they can saturate much faster. Weaker carbon filters may only last a matter of hours in these situations. Many people replace carbon filters when odours stop improving or based on the smell test Final Takeaway: Air purifiers can play a useful role in managing odours and VOCs - but only when they include meaningful amounts of activated carbon and enough airflow to circulate room air effectively. For best results, pair air purification with good ventilation and realistic expectations. Do air purifiers remove smells completely? Air purifiers can reduce odours over time, but they rarely eliminate them completely. Strong or persistent smells often come from surfaces, furnishings, or building materials, which air purifiers can’t clean. Ventilation remains essential. Do HEPA filters help with odours? No. HEPA filters are designed to capture particles like dust, pollen, and smoke particles, but they do not remove gases or smells. Odour and VOC reduction requires activated carbon. How much carbon do I need for odours? There’s no single answer, but more carbon generally performs better. Purifiers with only a thin carbon layer may help briefly, while units with hundreds or thousands of grams of carbon provide longer‑lasting odour reduction. Can air purifiers help with smoke smells? They can help reduce airborne smoke particles and some smell, but smoke, especially from cigarettes often penetrates walls, carpets, and furniture. In those cases, air purifiers have limited impact on lingering odours. Relevant Articles: The Best Air Purifiers in New Zealand: 2025 Comparison Read more New Home Smell Making You Sick? Tackle VOCs with These Tips Read more How to Stay Safe in Smoke | NZ Guide to Clean Indoor Air Read more