Risk of respiratory illness as dust descends

Press Release – Science Media Centre

Sydneysiders are dealing with the fallout from one of the biggest dust storms to hit the city in decades. Calls to emergency services in Sydney from people reporting respiratory problems spiked today as dust blown in from the Australian outback clogged …
SMC Alert
23/09/09

Risk of respiratory illness as blanket of dust descends

Sydneysiders are dealing with the fallout from one of the biggest dust storms to hit the city in decades.

Calls to emergency services in Sydney from people reporting respiratory problems spiked today as dust blown in from the Australian outback clogged the air and brought the city to a standstill.

Our colleagues at the Australian Science Media Centre in Adelaide gathered comment from scientists across the Tasman. Feel free to use these quotes if you are following the story.

Dr Phillip Thompson is Director of the Centre for Asthma, Allergy and Respiratory Research at the University of Western Australia:

“Dust storms are particularly hazardous for anyone with chronic lung disease or sinus disease. Once the particles per cubic metre are above 300 dust storms pose a risk to lung health. Large particles are trapped in the nose and sinuses and can worsen sinusitis for those who suffer from this debilitating condition. Smaller particles reach the lower airways and act as an irritant and can trigger asthma in those whose asthma is unstable.

“The nature of the dust can also be a major problem. It can contain a lot of plant materials such as pollen particles and cause severe allergic reactions or if it contains a lot of fine mineral dusts you can clog up the airway defense systems and increase the risks from infections and if a sustained exposure occurs it can lead to lung damage and scarring.

“Patients with asthma, emphysema, bronchitis, COPD, Bronchiectasis or anyone with a current chest infection are at risk and should take preventative measures such as staying in doors with windows and doors closed, increasing medication where this is part of their self care plan and/or seek medical advice if they worsen. Repetitive/seasonal dust storms as occurs in parts of China can cause impairment in lung development in children. It is important to know the size of particles, the mineral and organic content of the dust to truly advise on the risk of dust exposure.”

Professor Nigel Tapper is Professor of Environmental Science and Head of the School Geography and Envir. Science at Monash University:

“We currently have an ARC Discovery grant looking at Australian dust sources, composition, transport and impacts. These dust storms are some of the largest in the last 70 years. Improved pastoral management has been largely responsible for this lack of recent dust storms. However 10 very dry years over inland southern Australia and very strong westerlies have conspired to produce these recent storms. One storm last week passed over Melbourne to New Zealand and we are currently analysing dust collected last week from the Southern Alps of NZ.

“We are particularly interested in the impacts of dust in terms of ocean/ecosystem fertilisation and the microbes that are co-transported – with potential implications for ecosystem health (e.g. potentially the Great Barrier Reef, etc).”

Associate Professor Michael Box is from the School of Physics at University of New South Wales:

“The Lake Eyre Basin area of central Australia is a dusty place, especially in early spring. Dust storms originating in this region are common, although it is far less common that the dust is carried the 1,500 km to Sydney, and beyond. However, with winds of sufficient strength and the right direction dust may be carried off the Australian coast – even as far as New Zealand.

“The sky is “red” because of sunlight absorption by the suspended dust. Australian desert dust is much redder than, say, Saharan dust due to its higher iron oxide content, which absorbs blue light. In storm events like these, Australia “freely exports” large quantities of iron to the oceans, which can fertilize plankton blooms. These blooms may play a beneficial role in climate change, absorbing carbon dioxide from the atmosphere.

“Dust concentrations in Sydney are likely to be at least 10 to 20 times the recommended air quality goal. The sizes of the suspended particles are likely to be around one to a few micrometres, which are probably too large to penetrate deep into the lungs. Nevertheless they are small enough to enter airways, irritating the lungs of healthy people and adding to breathing difficulties in people who already have such problems.

“Desert dust particles are relatively insoluble and so are not as easily removed by rain as are sulphate particles from fuel burning. They are likely to settle out on hard surfaces, and may find their way into hard to clean places.”
Dr Ross Mitchell is from CSIRO Marine and Atmospheric Research:

” We run a couple of monitoring stations in the outback. One is at Birdsville and one is in the southern Strzelecki desert at Tinga Tingana – about 400kms apart. They are quite close to the source regions of dust storms in Australia. The Lake Eyre basin is the main Australian dust source region. We are trying to get a handle on the dust from there rather than further downstream.

“What we have seen over the last 24 hours is really quite unusual. At the southern of those 2 stations at Tinga Tingana we have seen elevated dust through the whole day. The units we use in this measurement are ‘inverse mega metres’, and a number of about 1000 constitutes a really severe dust storm. Normally you will see an event that will peak at this level and then drop back. What we saw yesterday was a signal that maintained itself at about that level for the whole day.

“What we saw 400km further north at Birdsville was even more surprising. We had a pre-frontal dust level of just under 1000 and then when the front came through at about 2pm local time, we got a reading of 7200 which is 7 times greater than what is already a pretty significant dust event. This is the highest reading we have ever observed at either station over the last 10 years.

“We have been observing at these places since 1997 and if you look at the ten years from 1997 to 2007 there was a big change in dust source emission following the 2002 drought. The dust season runs from spring to summer – essentially from September through to March. With some minor changes from year to year, if you take an average dust level from 2002-2007 and compare that with 1997- 2002, there is about a factor of two difference. Dust emissions in 2002-07 are about two times higher than the preceding five years. There does appear to be a significant increase on a decadal time scale.

“What was unusual about this storm is that it lingered the whole day. The persistence of this storm is unusual and we observed that at the source regions too. We are still trying to work out exactly where the source regions for this storm were.”

Professor Guy Marks is a Respiratory Physician and Clinical Professor at the University of Sydney and Head of Respiratory and Environmental Epidemiology, Woolcock Institute of Medical Research:

“There are very high levels of fine particles in the air in Sydney at present. The effect of fine particle pollution on respiratory health is at least partly influenced by their composition. For example, during thunderstorms ruptured pollen grains in the air can cause severe epidemics of asthma. The common source of particulate pollution is combustion products – vehicle and industrial emissions. These are associated with worsening of respiratory and cardiovascular disease, causing excess hospitalisations and deaths. The effect of earth (crustal) particles on health is less well studied. Several publications from Taiwan have shown small but non-significant increases in respiratory and cardiovascular admissions in the day or two after dust storm events.

“Hence, the likely impact of the current event in Sydney is rather uncertain. The best advice is caution. People with severe respiratory disease (asthma or COPD) would be wise to stay indoors with the windows closed and to have their reliever inhalers available. ”

ENDS

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