Dr. Christine Cowie, from the University of New South Wales' centre for pollution, energy and health research, says that expert concern is around particle matter size that is a consequence of combustion pollution such as bush fires.
"When our bushland burns it produces a number of different pollutants but from a health perspective, the one we are concerned about, is particular matter.Fine particle matter which is less than 2.5 microns in diameter, one twentieth of a strand of hair, mixes with larger particle matter and that forms a visible haze," says Dr. Cowie.
"Our concern, however, are those tiny particles that are small enough to be breathed deeply down into our lungs."
Dr. Cowie says that the particles not only full penetrate the respiratory system, they are small enough to be absorbed into the blood stream which can cause further damage to other organs in our body.
While short term health effects are well known to scientists, the long term effects of bushfires on human health haven't lead to conclusive evidence.
Increased hospitalisation, increased diagnosis of respiratory diseases, increased heart attacks and stroke, are all consequences of short term exposure but Dr. Cowie says there is not data for effects that may occur "year in, year out".
"The long term effects of exposure in Australia, for example what is happening in Sydney now, are not well studied. We know about short term, acute conditions but not how it progresses, if it does, down the track"
Dr. Cowie says that governments and researchers are trying to determine whether some sources of pollution are more hazardous than others.
"The studies that we have, have mixed results. There is enough evidence to incidate that pollution from combustion, that is pollution created when something is burnt, is more hazardous that pollution or particles that come from wind blowing dust or wind blowing salt in the air. In other words, any particle matter that comes from combustion, be it bushfires or transport, is harmful. However, at this stage we don't know how pollution ranks within that category of combustion pollution.
Dr. Cowie says that people who have pre-existing respiratory issues or serious chronic issues should opt to stay indoors as much as possible during high pollution days.
She also recommends keep doors and windows closed, and if possible, keeping air conditioning on "air recycling" modes.
"People need to listen to doctor advice and continue to properly take medication. Short term relief for those without air conditioning can be found in local shopping centres, but of course, this is a short term solution."
Dr. Cowie adds that research into the effectiveness of masks is also inconclusive, but doesn't discourage people from trying.
"It needs to be a specific type of mask, but even then, evidence doesn't prove that it is always effective. However, if people have difficulty breathing, there is no harm in trying a mask as a solution."
Fires which have been burning since early November continue to destory homes and property on the eastern coast of the country.
Almost 120 bush and grass fires are burning across NSW, 50 of those are uncontained and more than 2,000 firefighters being supported by aircraft.
