If you buy one, it's important to get an air purifier that's appropriate for the size of the room you want to use it in.

Rooms reeking of smoke, alarms going off due to the visible haze inside your home, waking up in the middle of the night smelling smoke in the air.

Australia's bushfire crisis is affecting air quality and the wellbeing of many of us. Smoke haze has been blanketing many parts of the country, including some of our major population centres - Canberra, Sydney, Melbourne and other capitals.

Experts agree we need to stay inside and out of the smoke as much as possible, especially when the air quality is hazardous.

"The guidance that's being provided of staying indoors with your doors and windows closed is good up to a point," says environmental scientist Amanda Wheeler, of the Australian Catholic University, who has conducted research evaluating interventions to improve indoor air quality affected by smoke.

"Houses naturally breathe, because you don't want to build up carbon monoxide inside a house until the point that you're going to keel over."

How good that advice is depends on how airtight or leaky your house is, as that determines the rate of air exchange between the outdoors and inside, says director of the International Laboratory for Air Quality and Health, Lidia Morawska of Queensland University of Technology.

Queenslanders, for example, have lots of holes and gaps to allow for a much higher rate of air exchange than dwellings designed for the cooler temperatures in more southerly climes.

Do you have questions or concerns about air quality that you'd like us to put to an expert? Please email health@abc.net.au and we'll try our very best to find an answer for you.

Try to seal your house as best you can to stop these pollutants coming into your home in the first place, Dr Wheeler said.

You can use a reverse cycle air conditioner, just make sure you switch it onto recirculate mode so it's not drawing in air from outside.

You shouldn't use evaporative cooling air conditioning as these systems draw air in from outside. So turn these off to keep the smoke out, although that will obviously leave with you a very hot house.

Fans can keep your house cooler and possibly help get rid of the smell, but on their own fans don't remove smoke particles.

The best option is a recirculating air purifier, which has a HEPA filter, but these are expensive and mostly unavailable at the moment.

As Dr Wheeler's research has shown, it's important you open your windows and doors once the smoke starts to clear. This can help you get rid of the small smoke particles that have been trapped indoors, which should also help dissipate any smell.

A lot of people will be affected by smoke regardless of the level of the pollutants, Dr Wheeler said.

But if the air quality seems worse inside your house than it is outside, then it might be the time to open up.

There are a number of websites and apps that give you hourly updates on air quality in certain, if you keep an eye on these they can tell you when the air quality is improving. But look out for hourly updates, as opposed to the 24-hour averages.

Bushfire smoke, like smoke from any combustion, contains over 4,000 different components, said Professor Morawska.

Potentially the most hazardous pollutant in this mix, and the one you've probably heard the most about, are the ultrafine particles or PM2.5.

We can track some of these particles smaller than 2.5 micrometres, but not all of them, Professor Morawska said, so there could be smaller particles getting into your home that we can't detect.

Mark Taylor of Macquarie University says filters can strip out nearly 100 per cent of all the particles in the air, and will help eliminate any excess amount of particles in people's living environments.

As the smell of smoke is predominantly associated with the particles, the air purifier should also help with the smell of smoke in your room too.

You need to buy the right-sized air purifier for the room you want to use it in, you'll find this information on the product.

"If the room is too big, it's just going to keep pumping air through the filter but it's never going to catch up and clean the air," Dr Wheeler said.

You may need to run your air purifier at quite a high setting, at least initially, if you have a lot of smoke you'd like to remove, and that will be pretty noisy.

Her previous research looked at how air purifiers handled wood smoke coming indoors and found a 50 per cent reduction in smoke levels in the space.

"The main difference really is the levels of the smoke. For bushfires we've seen concentrations of fine particles that are astronomical at the moment," she said.

"Knowing whether these air cleaners are going to work at those really high concentrations is challenging at this point."

We also don't know how well they'll go being used over a longer period of time, as studies generally measure their efficacy over a few days or a week at a time.

While people have been sharing tutorials for how to may do-it-yourself air purifiers online, Professor Taylor says it's impossible to say how effective they are as they haven't been tested.

As well as checking the outdoor air quality index, using devices to monitor the indoor air quality inside your home can be very helpful when there's a lot of smoke around, says architect Shamila Haddad from UNSW.

This is especially true for those more vulnerable to the effects of smoke including older people, children, pregnant women and people with asthma and allergies.

"Affordable indoor air quality monitoring devices can be found and purchased online from different suppliers," Dr Haddad says.

These devices may allow you to access real-time data through a website or mobile app. Some also allow you to perform spot measurements of your indoor air quality.

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