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How to improve indoor air quality during this bushfire season

Bushfire smoke is becoming a large topic in the forum. We’ve come up with some options for keeping the smoke out, as well as what you can do to improve the quality of air in your home.

Do you have any tips to sealing your home you’d like to share with the community? Comment below.


If only it was that simple! I have to keep the doors and windows closed all night most of the time, as that is when the SE wind blows thick smoke over me from a nearby fire (currently >20000ha and been burning for weeks). During the day when the wind is lately from the W or NW, the smoke is less, but there are fires in that direction too. So it just stays very hot in the house, with minimal chance to get the smoke smells out. The recently purchased air purifier does help, but cant keep up when the smoke is at its worst, as it still leaks into the house, and I have to go in and out a bit during the day.
I have opened the house up at night when the smoke smell outside was less than inside, but have been woken up or slept through thick smoke coming in, rather unpleasant on the eyes, nose and throat!
It’s been like this since October, with numerous nearby fires, so vacuuming to clean up the smoke and dust is rather pointless- it just keeps on coming back.

This morning, when I woke up with windows still open and stinging eyes, sore throat etc.
Some days it is much worse.

Yesterday it smelt like pine plantations burning, this morning it was more like rubber tyres.


Of course, closing up the house only works if your home is well sealed.

“Make sure any major drafts are blocked with draft excluders and seal any leaky windows,” Barnes also suggests.

Closing up the house and sealing doors and windows sound nice, but in reality it is very difficult to achieve! Here are a few issues I can think of which would prevent a house being sealed:

  • Aluminium sliding doors and windows all have gaps built into their tracks to allow rainwater to escape. It would be difficult to block these up.
  • Roofs, particularly terracotta tiles ones are very air leaky, and smoke would then penetrate the roof cavity, and down any vents.
  • Bathrooms and toilets often have extractor fans which would allow smoke in.
  • Older houses have wall vents which can not be closed off.
  • Many houses in more tropical climes have louvre windows. These are practically impossible to seal.
  • The ‘Queenslander’ type elevated homes were designed to allow air to circulate from underneath the house up through and out the top of the house. Can’t seal them.

Even modern apartments have gaps and vents.

Perhaps if we just say, close your doors and windows? That may be achievable.


For a fire out the back that has a short duration, 12 hrs or less. Perhaps it is a strategy that could work for some designs of homes. EG. Modern homes designed to be energy efficient are likely to be lower leakage.

Every home needs to change the air several times a day. So what ever air is outside will become at some time inside air. The current bush fire events last days through to weeks in some areas.

Is it a practical solution to consider sealing the house for days or even weeks?


A great and essential point to make.

My father and I sealed his home a few years ago almost entirely ourselves. It was a lot of work and we were fortunate to not have to consider doing it due to bush fire events.


My house leaks like a sieve! There’s no way to seal it, my window rattler a/c means gaps. I have draft stoppers at doorways but with the cat going in and out (only twice a day thank goodness) theres quite a bit of stinky smoke ingress. I will be getting something done about it when I manage to get a split system a/c installed. IN the meantime I jut run my a/c 24/7. Its not a fabulous solution but it helps a bit. According to my Netatmo, at least, having the a/c on in the lounge area keeps CO2 levels down, whereas 2 nights ago, I switched off at bedtime and on again in the morning. CO2 started rising to levels I normally only get when using the gas cooker, but when a/c went on in the a.m. started coming down right away. I don’t know why, and TBH do not care.

I just know it worked for me (and let me breathe a lot easier) and I am so glad I don’t live in Canberra which has been having a hellish time with smoke in the past few days. Here in Newcastle we are getting smoke from a fire at Wangi Wangi, and a couple further up the valley. Nothing like that being endured by other locations.

Oh for a good purifier, and a split system a/c!!


I’m surprised at the smell of smoke in StKilda, a bay suburb of Melbourne,
The air quality shows moderate quality,
PM2.5, and there’s a strong wind warning SSW with gusts over 65Km/h.

It’s difficult to keep the flat air tight but
soon I’ll close all the window and turn the aircon on.

My thoughts and prayers are with those in the more badly affected areas.


An interesting observation @SueW. The levels you observed of up to 1100ppm are not considered hazardous to health. Although twice that of fresh air urban environments typically also have elevated levels of CO2 due to motor vehicles, gas usage, etc

A higher urban level of CO2 may be associated with greater motor vehicle exhaust or similar pollution. It’s not the CO2 that is the hazard. It’s the other stuff that may be produced along side it that is the hazard. A high CO2 level is not proof any of the nasties are present. It is a simplistic indicator there may be elevated levels of pollutants present.

The occupational safe level for CO2 over 8hrs is a TWA (time weighted average) of 5,000ppm. This is equivalent to 0.5% by volume. In itself CO2 is not considered toxic. It’s an inert gas under normal conditions, even used as a shielding gas with high temperatures in welding steel.

The effects of higher levels of CO2 are most commonly associated with less oxygen in the air. It’s also generally considered safe to have oxygen levels as low as 19.5% compared to the norm of 20.9%.

CO2 is heavier than air and will displace oxygen. You do need a lot of CO2 to accumulate for this to occur. Much more than 0.5%.

Assuming you are not burning candles or doing anything else to consume the oxygen in the house it would appear you are well within the accepted safe levels for CO2. However another gas, Carbon monoxide (CO) with an 8hr hazardous TWA of just 30ppm is often the big silent killer. CO actually enters the blood stream and blocks the transfer of oxygen around the body. It’s effects are not instantly reversed by simply moving to fresh air. Kero or gas heaters, wood fires, etc can be deadly in poorly ventilated spaces.

With rising CO2 in a perfectly sealed environment there is a long term risk of asphyxiating, typically due to the lack of oxygen. It might take days for the scenario to develop.

One source suggests the average adult (no heavy exertion) breaths in approx 11m3 of air a day and consumes 4-5%, or approx one quarter of the oxygen in the air in each breath. Note there is 21% O2 to start with. And many times 11m3 of air in a small unit, or typical bedroom. Not typically a risk for a short period, but certainly a real risk over days or weeks.


If I cant breathe properly, its a problem. I could not breathe properly when I got out of bed, I checked the Netatmo… What can I say. Those levels might be fine for some but for me, personally, they are hazardous. I have heart and lung “issues” and have no plans to drop off my ever-shrinking perch just yet. I dont burn candles, and there was no reason for the CO2 levels to rise overnight… except theres smoke getting in via the leaks. Normally it putters along between 500 and 700ppm. I do not like it going up to 1000 regardless of the numbers quoted as safe. Yes, no idea what else is in the house apart from that, but like I said, DO NOT CARE, IF MY BREATHING IMPROVES!!


Given the current poor air quality that is understandable. We all have different personal circumstances and health conditions. We’ve just spent time on the road and arrived in Newcastle. There is heavy smoke haze evident through the northern half of NSW. It’s difficult to imagine the impacts of the more significant fires in NSW and Victoria.

The amount of microfine PM2.5 measurable dusts in the atmosphere as noted in other posts is very significant. That these dusts through continued exposure have adverse health impacts is factual. The risks are greater for those of us with respiratory impairment or conditions.

It’s informative to consider the marketing for the Netatmo Indoor Weather Station (by Legrand).

This advice from the product website appears to be misleading.

The Netatmo Weather Station measures indoor pollution levels through a CO2 sensor, sending you alerts so you can air out your home when necessary and live in a healthier indoor environment.

In respect of local advice on protection from smoke pollution by improving the sealing of your home?

The Netatmo does not measure particle pollution PM10 or PM2.5. Opening up the home on the basis it is polluted because of a higher than normal CO2 level will only introduce more bushfire smoke particles to a home or room, increasing the pollution levels that the Netatmo does not have instrumentation to measure. That an enclosed room over time becomes stuffy and may have increased CO2 levels is perhaps the logic behind the marketing of the Netatmo product. CO2 can be readily detected and measured using infra-red based electronic devices. Simple and low cost.

The advice to date on reducing particle pollution in the home through an air purifier with effective HEPA filtering is reliable. Some models have a method for reporting the relative air cleanliness/dust level which is a bonus. Reliability/accuracy indeterminate.

Without a thorough Choice review the marketing claims for the Netatmo products or similar are open for the purchaser to assess.

The only aspect of air quality a CO2 monitor can report is the relative volume of CO2 based on the sensor location. Without CO2 all plant life would cease to exist. It is not measuring the components of air pollution that have known direct health risks. Although increased CO2 in the environment is a contributing cause of climate change. The root cause arguably has two legs and walks in an upright stance?


There is a difference between the smell of smoke and smoke particles.

Smoke smell is made up of volatile organic compounds in the form of gases. These VOCs give smoke its distinctive odour and can cause irritation of the nose, eyes, lungs and the rest of the respiratory tract.

Smoke particles is different and are fine particles or solids which are suspended in the air. The smaller sized particles such as PM2.5 can be inhaled deep into the lungs where they can be trapped (and not exhaled). These particles can also cause irritation to the nose, eyes and throat.

Smoke smell is very difficult to keep out of ones house as any leaks in walls, floors, ceilings can allow the VOCs to enter as they are a gas mixed up in the air we breathe.

It is also worth noting that while smoke may be smelt, it doesn’t necessarily mean that one is also breathing in smoke particles. While I haven’t checked the specifications of air purifiers, if their purpose is to remove particles, they will have little effect in removing the smell of smoke (gas). To remove VOCs, while possible, needs a different filter system/technology.


Some come with activated Charcoal filters to remove VOCs. Bur like HEPA filtering it will depend on how much air bypasses the filters on it’s way through the machine, and the quality of the filters HEPA and otherwise as some are not “true” HEPA and some charcoal filters are not made well to be properly effective eg too thin material so not enough charcoal to trap the VOCs.


I think anyone with just half a brain would realise that you don’t open your house to outdoor pollution. Netatmo measures PM2.5 outside the house. It calls levels which we would say were unsafe, “very low”/. I ignore it. I pay attention to AirVisual apps and the NSW government site at

The Netatmo does the job its designed for. It tells me when indoor CO2 levels are high and then I decide what to do about it, and it tells me indoor and outdoor temperatures. I bought it for the temps. Now FFS leave it alone.

1 Like shows air pollution 440
(Hazardous) for StKilda.
All my windows have been shut during the night and this morning, except there’s a fixed louvre small one in the separate toilet, it’s high on the wall and behind the bowl, and I can’t place a stepladder in there, but I’ll see what I can come up with to try and keep the air out with a cardboard rectangle perhaps?


A heavy Curtain may also work to keep the air cleaner. The curtain might also be more attractive than cardboard in the space, though a laminated picture on the cardboard might also provide a degree of attractiveness. Sadly smoke and other pollutants are becoming a more everyday experience in all our houses other than those that rely entirely on air filtration and air locks to keep the air clean.

1 Like