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

We're well known for our breathtaking natural landscapes, often associated with clean air and an untouched environment. However, there are areas of the country where poor air quality issues are an unfortunate reality. Let's take a closer look at the causes of air pollution in NZ. Air Pollution: The Big Picture As per the latest LAWA Air Quality National Picture Summary, NZ has relatively good air quality overall. Yet, in some regions, people are exposed to higher levels of particulate matter, particularly during the winter months. This disparity arises due to several factors, such as weather conditions, geography, and the nature and volume of emissions present in each area. Winter Woes: Home Heating and Air Quality As we previously discussed in our blog on winter air quality issues, the lack of wind on colder winter days and the occurrence of inversion layers can trap particulate matter close to the ground, causing pollution levels to spike. Wood burners are popular in these areas, which emit particulate matter. The Role of Vehicles in Air Pollution Motor vehicles, especially those that are diesel-powered, are significant contributors to air pollution in NZ. They emit high amounts of pollutants such as nitrogen dioxide (NO2) and particulate matter. Factors like brake wear, tyre wear, and the presence of an older vehicle fleet compound the issue. Nature's Role in Air Quality At times, nature itself contributes to spikes in air pollution. Events like wildfires and occasional volcanic eruptions introduce large amounts of particulate matter and gases into the atmosphere, affecting local air quality. Insights from LAWA’s 2023 Summary According to the LAWA (Land Air Water Aotearoa) summary, in 2022, 42 of 60 monitored sites met the New Zealand standard for daily average PM10 concentrations. However, the monitoring of smaller particles (PM2.5) has revealed that these can exceed international guidelines more often than PM10. These tiny particles pose more significant health risks as they can lodge deep into our lungs and even reach the bloodstream. Through enhanced monitoring efforts, regional councils and unitary authorities aim to understand and manage air quality more effectively. Measures to Improve Air Quality As we gear up against winter cold, we can also protect ourselves from air pollution. Monitor the Air Quality Monitoring can help us make informed decisions about indoor stay times during poor air quality periods. LAWA has a great air quality dashboard which can tell you more about the trends in your area. For live air quality monitoring check out the aqicn website. It can also help to monitor your indoor air, we have affordable and high accuracy air quality monitors available on our website. Air Purifiers and Filters Quality air purifiers can remove harmful particulate matter from your home's air. Opt for purifiers with HEPA filters to remove PM2.5 particles. We provide a range of proven, affordable and effective air purifiers from Smart Air. Final Thoughts While New Zealand enjoys a reputation for clean air and a pristine environment, there is plenty of room for improvement. Armed with knowledge and understanding, we can better tackle the complexities of air pollution.

Air quality is an essential but often overlooked aspect of our well-being. In New Zealand, many remain unaware of how winter weather can profoundly affect the air we breathe. The Unseen Winter Culprit Winter air pollution in New Zealand is mainly shaped by weather patterns and heating choices. In the colder regions, while less common than previous years, we still see fireplaces being used for warmth. These emit particulate matter; tiny harmful particles into the air we breathe. Even though recently there have been tightened standards as far as emissions from these, they've focused on reducing the larger PM10 particles. The levels of PM2.5 seen in the air however, frequently exceed WHO recommendations. Inversion Layers: A Winter Phenomenon The New Zealand climate significantly influences air quality. In winter, many areas experience cold, still nights. These conditions, along with geographical features like mountains, create 'inversion layers'. This traps cold air and pollutants close to the ground, boosting harmful particle levels. We commonly see these occur in valleys and parts of Canterbury, Otago, Southland and Marlborough. Inversion layers occur when a layer of warm air sits on top of cooler air. This is the reverse of what we normally see where air gets cooler at higher elevations. This "lid" traps pollutants, contributing to higher PM10 and PM2.5 concentrations. PM10 and PM2.5 are particulate matter, or tiny particles in the air. PM10 particles are less than 10 micrometres in diameter, and PM2.5 are smaller, less than 2.5 micrometres. The tiny PM2.5 particles are concerning, as they penetrate deep into the lungs and bloodstream. Health Implications of Poor Air Quality Air quality influences our health. Both PM10 and PM2.5 pose health risks. The smaller PM2.5 particles, which can infiltrate our respiratory system, exacerbate conditions like asthma and COPD and can contribute to heart disease and lung cancer development over time. The World Health Organization states PM2.5 exposure can lead to respiratory and cardiovascular issues, hospital admissions, and mortality from cardiovascular and respiratory diseases and lung cancer. Understanding air quality's link to health is vital, especially for those in colder New Zealand regions, where winter pollution can be harmful. Pollution levels in these areas can reach unhealthy and even very unhealthy levels at times. Measures to Improve Air Quality As we gear up against winter cold, we can also protect ourselves from air pollution. Monitor the Air Quality Understanding the air quality in your area is important. In many countries checking the air quality is as common a task as checking the weather. Monitoring can help us make informed decisions about when to go outside and for how long during poor air quality periods. LAWA (Land Air Water Aotearoa) has a great air quality dashboard which can tell you more about the trends in your area. For live air quality monitoring check out the aqicn website. It can also help to monitor your indoor air, as outdoor pollutants can seep into your home. Personally, I found in my Christchurch home that during cold winter nights the air inside my home would often reach unhealthy levels due to the pollution. Want to check if the same happens to you? We have affordable and high accuracy air quality monitors available on our website. Air Purifiers and Filters Quality air purifiers can remove harmful particulate matter from your home's air. Opt for purifiers with HEPA filters to remove PM2.5 particles. We provide a range of proven, affordable and effective air purifiers from Smart Air. Clean Heating Cleaner heating options can improve air quality. If possible, consider shifting from wood burners to cleaner heat pump options. Wrapping up Awareness is the first step in enhancing our winter air quality. The more we understand, the better we can protect our health and communities. Stay informed, take action, and breathe easier this winter.