Rachael Neumann was six months pregnant with her first child when the smoke in Canberra was at its worst this January.

Key points: Atmospheric chemist Clare Murphy says bushfire smoke can contain harmful toxic gases

Atmospheric chemist Clare Murphy says bushfire smoke can contain harmful toxic gases She says masks bought by many Australians would not stop the inhalation of these gases

She says masks bought by many Australians would not stop the inhalation of these gases But she says she is not too worried as the human body "is amazing in its ability to recover"

She told 7.30 she was anxious and frightened about what she was breathing in and what it could be doing to her unborn child.

"It was just really challenging and really stressful. And with all the hormones as well — there were a couple of days where I just could not stop crying. It was awful," she said.

Her husband Shalev Nessaiver was so worried that he started compiling regular updates about the smoke. They became so popular amongst their friends that he started a Twitter feed to share the information he was gathering.

"I would start to look at weather patterns and smoke forecasts and combined a bunch of data to figure out, OK, here's where it's going to be bad during the day, here's where it might be a little bit better," Mr Nessaiver said.

Rachael Neumann and husband Shalev Nessaiver moved from Canberra to Melbourne due to bushfire smoke in the capital. ( ABC News )

"Generating these forecasts became so chaotic because of all the new fires that were springing up. I just built an automated version that pulled data from a couple of different sources and displayed it on a website."

Around them the smoke and air quality were getting steadily worse. At one point, the air quality rating in Canberra was more than 22 times the hazardous rating.

To escape it, they decided to move to Melbourne.

"It got to the point where we were barricading ourselves in our bedroom, sealing the vents and the tops and the bottoms of the doors," Mr Nessaiver said.

Rachael Neumann and Shalev Nessaiver sealed their house as best they could and used an air purifier. ( ABC News )

"We had an air purifier running full blast. We can't live like this, right? You can't.

"It's just not safe for anyone, regardless of being pregnant or not."

"We just booked flights the next morning and said, 'We cannot be here like this'."

'We've all been part of a big mass experiment'

Sydney blanketed in bushfire smoke in December. ( ABC News: Michael Troy )

At the same time that Ms Neumann and Mr Nessaiver were worrying about their unborn child, University of Wollongong atmospheric chemist professor Clare Murphy was setting up an air monitoring experiment at Lake Cataract, south of Sydney.

Her team had not initially been planning to examine bushfire smoke, but she told 7.30 the plume from the Canberra and NSW South Coast blazes proved to be irresistible.

"We haven't done much analysis [yet] because we have been so busy keeping the instruments running. But this experiment finishes at the end of March, and the data will keep us busy for months and years to come," she said.

Professor Murphy said past work examining hazard reduction burns gave her a strong indication of what millions of Australians were breathing in this summer.

"It's not just the particles in the smoke that they need to worry about. There are a lot of toxic gases like formaldehyde, ammonia, hydrogen cyanide," she said.

"I could carry on naming, but quite a few."

Professor Clare Murphy says the smoke haze would have contained a number of potentially toxic gases. ( ABC News )

She told 7.30 that masks bought by many Australians would not stop the inhalation of these potentially toxic gases.

"Particulate matter will have been filtered out at least to some degree, depending on how well [the mask] fits. But the gases will go through and people really don't know how bad it is," she said.

"I think that the extent of the exposure that we saw in the bushfires this season was unprecedented. And I think we've all been part of a big mass experiment on populations and I think time will tell how bad it is.

"These gases are toxic and they're known to attack different parts of the human body. The reason that they're not monitored by air quality monitoring stations is that normally they will be below the detection limit of the instruments that you could easily get hold of.

"So in this smoke, they're very elevated and you can see the concentrations quite clearly."

'The human body is amazing in its ability to recover'

Pedestrians walk through smoke on Sydney's George Street in December. ( AAP Images: Paul Braven )

Despite this, Professor Murphy is not overly concerned, even though she has been breathing in this air herself.

"I don't think people should be losing any sleep over it," she said.

"Air pollution does link in epidemiological studies with poor health outcomes, but it's a statistical thing and it's something that affects people who already have lung problems.

"I think that on the plus side, Australians do often enjoy quite good air quality and the lungs, the human body, is amazing in its ability to recover."

The Australian War Memorial in Canberra in January. ( ABC News: Jordan Hayne )

Ms Neumann and Mr Nessaiver have no regrets about their decision to move from Canberra to Melbourne.

"It's been nice to just take a walk outside without a mask," Ms Neumann said.

"When we first got here, we were like, 'Wow, this is so different.' Because it had been so long since we'd been able to do that."

Mr Nessaiver told 7.30 they were looking forward to meeting their child.

"I think it's been a great pregnancy and the baby is 100 per cent OK," he said.

Changes to recovery fund

The Federal Government's National Bushfire Recovery Agency will today announce changes to its $2 billion recovery fund to make it easier for small businesses and primary producers to apply for grants and loans.

7.30 has been told the agency will be broadening the definition of what a "bushfire-affected business" is, meaning that money will not just be flowing to businesses that were physically burned in the fire.

The agency's coordinator, Andrew Colvin, has conceded it is currently taking too long to get loans and grants into the bank balances of the victims of this summer's devastating and deadly fires.

A statement from the Minister for Emergency Management, David Littleproud, said the changes would "include a new $10,000 grant, quicker access to existing loans and more boots on the ground to help small businesses access appropriate help".

7.30 also understands changes are being made to the package that is currently available for primary producers to help them get back on their feet.

Watch part 3 of 7.30's bushfire special tonight.

