Air Purifiers for Smoke in NZ | Woodburners, Fires & Winter Haze
on Dec 10 2025
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
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
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.
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.
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.
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.
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.
