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

Accurate PM2.5 measurement matters if you want to understand real-world air pollution exposure indoors. While many low-cost air quality monitors claim to measure PM2.5, actual performance can vary significantly between models. To better understand how different consumer-grade monitors compare, we looked at a group of commonly used models from Qingping and Temtop. Rather than relying only on manufacturer claims, we anchored our comparison to models with independent field test data, then examined how closely the remaining units tracked alongside them in real indoor conditions. All six monitors were co-located on the same bench and run continuously over several days. While absolute readings varied slightly, the overall patterns and trends moved together closely, with relatively small gaps between devices. This provides useful context for how these monitors behave in practice, particularly when used to track changes and spikes in PM2.5 rather than focusing on a single absolute number. Independent Testing Anchors Southcoast AQMD, based in California has a program where they compare air quality monitors with high grade reference equipment. This provides independent test data for dozens of models, from low cost ones like the QP Lite to ones costing thousands of dollars. For PM2.5, all the results are published here. Several units already have results available from Southcoast AQMD. All showed strong correlations with the reference equipment for PM2.5 measurements, and low mean errors - often beating monitors costing thousands of dollars!  Model Field R2 (Correlation) Field MAE (Absolute Error) Qingping Lite 0.85 to 0.93 1.8 to 3.6 Qingping Pro 0.86 to 0.90 1.8 to 2.3 Temtop LKC-1000S+ 0.91 to 0.92 3.1 to 3.6 Note, original model of Pro and Temtop LKC were tested, updated models used for our comparison testing. Why PM2.5 Matters PM2.5 are tiny particles that can reach deep into the lungs and even the bloodstream. When air pollution is talked about, it typically refers to levels of PM2.5, due to the serious health impacts. In New Zealand, indoor levels can often be higher than outdoors. Seeing the levels and changes in your home or workplace can help you decide if interventions such as ventilation or air purification is required.  What we tested   Models: Qingping Lite, Qingping Pro 2, Temtop M10i, Temtop M10+, Temtop S1+ and Temtop LKC-1000S+ 2nd. Environment: Same bench in an apartment (Christchurch), co-located and away from air vents. Period: 14 - 18 August 2025, hourly measurement results Objective: Check how closely the models track together in real conditions, using indepdently tested units as the benchmark Method and limitations Recording frequency: We aligned measurements to the unit with the lowest recording frequency (M10+), so all results are reported hourly.  Time adjustments: Not all units were recording exactly on the hour, so the closest recording to the hour was used. In some cases this was 5mins before or after the hour. Units plugged in: All units were plugged in to ensure regular readings and updating PM2.5 Exposure: Two spikes occured due to cooking with the frypan. No air cleaning was used, in order to keep levels high for longer. Results By the numbers Most pairs have correlations between 0.95 and 0.99, indicating very high levels of correlation Typical difference: Around ~1 µg/m³ when averaged over the period Mean reading: Small spread across devices, mean PM2.5 reading for the each device across the entire period was between 3.2 and 5.0 µg/m³. Variances observed during initial PM2.5 spikes, due to timing of readings. A note about PM10 One of the reasons we focus on PM2.5 is that PM10 numbers from low-cost optical sensors are generally less reliable than PM2.5. This is shown in the Southcoast AQMD results, where PM10 accuracies were always quite a bit lower than for PM2.5. This essentially boils down it it being more complex to measure for PM10 sized particles. If you'd like to learn more, there's a great writeup about this here.