Air quality

Introduction

The quality of the air we breathe directly affects our general health and well being. The regular monitoring and maintenance of air quality is, therefore, extremely important for our overall quality of life. A key environmental issue which Australia currently faces is reversing the degradation of our ambient (outside) and indoor air quality. Aside from affecting human health, the presence of air pollutants in high levels can also adversely impact upon wildlife and vegetation.

Air pollution in Australia

In comparison with some other parts of the world, air quality problems in Australia are less severe. This can largely be put down a small population (relative to the size of Australia), the chemical make-up of our energy resources and high wind flows in our nation's capitals. Cities such as Los Angeles, Mexico City and Athens, on the other hand, are notorious for possessing extremely poor air quality. Australia does, however, have a poor record when it comes to contributing to the greenhouse effect. In fact, we are one of the countries with the highest per capita levels of greenhouse gas emissions. Air pollutants fall into three main groups: criteria pollutants, air toxics and biological pollutants. The levels of each of these in the atmosphere are measured using the parts per million (ppm) index.

Criteria pollutants

These air pollutants are the most closely regulated around the world. They include: carbon monoxide; lead; nitrogen oxide; particles; ozone; and sulphur dioxide. In Australia, the two criteria pollutants of greatest concern are particles and ozone.

Particles

Otherwise referred to as PM (particulate matter), particles include substances such as soot, smoke, dirt and dust. High levels of PM can be generated from human-induced activities such as industry, mining, construction, agriculture and transport. They can also be a result of natural processes such as soil erosion caused by wind. The major concern associated with the high levels of PM in the air is its association with respiratory illnesses and cardiovascular disease.

Ozone

The other major criteria pollutant responsible for poor air quality in Australia is ozone. It is important to note, however, that this harmful ozone should not be confused with the type of ozone which forms the Earth's protective ozone layer. While the presence of ozone in the stratosphere (the second atmospheric layer from the Earth's surface) is essential for regulation of the Earth's temperature and protection against harmful ultra violet radiation, unnatural levels of ozone in the troposphere (the closest atmospheric layer to the Earth) can be dangerous to humans. This ground-level ozone is formed when nitrogen oxide reacts with organic chemicals in the air. The reaction only occurs in the presence of sunlight, which is why this problem is worse during the warmer months of summer. Again, motor vehicle exhaust fumes are the largest contributor to excess levels of nitrogen oxide and a build-up of harmful ozone. See animation 1

Air toxics

Also known as 'hazardous air pollutants', air toxics are pollutants which can be dangerous to humans and the natural environment when found in high quantities. Their presence has been related to increases in the incidence of illnesses such as cancer and respiratory disease, as well as genetic and birth defects. Heavy metals are examples of air toxics that can be very harmful in this way. Air toxics can be emitted into the atmosphere from a variety of sources, so our exposure to them is largely dependent upon individual lifestyles and workplaces. People who work in factories where toxic fumes may be emitted would therefore have much more exposure to this type of air pollution than people who do not.

Biological pollutants

Included in this category are contaminants which are either living or produced by living things. Biological pollutants can include things such as mildew, mould, bacteria, viruses, pollen, decomposed plant and animal skin, and animal faeces. Heating and air conditioning systems can act as breeding grounds and catalysts for the distribution of biological pollutants if they become contaminated. Poor household cleaning routines can also contribute to the build-up of biological pollutants, which can cause illnesses and trigger asthma and allergic reactions in humans.

Other air quality issues in Australia

Brown haze

Sometimes on still winter days a layer of brown smog can be seen over the skyline of big cities. This type of air pollution is known as brown haze and it forms as a result of a 'temperature inversion'. This occurs when a layer of cold air becomes trapped underneath warmer air, preventing dust particles from rising into the atmosphere as they ordinarily would. See image 2

Photochemical smog

Seen more during the warmer summer months, photochemical smog is formed by a similar chemical process to that which forms ozone (discussed above). In the presence of sunlight, volatile organic compounds (VOCs), such as chemicals emitted from pesticides, paints, paint thinners and varnish, react with emissions from cars and factories, forming a whitish haze.

Indoor air problems

Australians spend, on average, about 90 per cent of their time inside. Monitoring and improving the quality of our indoor air is therefore extremely important. Although in general there is less known about issues related to indoor air quality, it has become increasingly apparent that this is in fact one of our major public health concerns. Indoor air can be contaminated by particles and many of the biological pollutants and air toxics previously listed. Findings have even revealed that given the right conditions, aerosols (fine liquid droplets) generated by spa baths can spread bacteria related certain diseases. Smoking in confined spaces is another contributing factor to the degradation of indoor air quality, however this problem has declined in Australia as a result of the bans on smoking in certain areas of pubs and clubs that were introduced in 2005.

The greenhouse effect

Australia is one of the biggest contributors to global warming. Our levels of greenhouse gas emissions are among the highest in the world. Carbon dioxide is a greenhouse gas emitted when fossil fuels, such as coal and natural gas, are burned to create energy. Coal provides around 45 per cent of Australia's energy and is therefore the biggest contributor to the country's greenhouse gas emissions. Queensland is the State that records the highest amount of greenhouse gases emissions per capita in Australia. In recent years Australia has fallen short of its targets for reducing greenhouse gas emissions, which seriously threatens the global environment.

Improving air quality

Efforts to improve air quality in recent times have included banning the use of domestic incinerators, banning smoking indoors and in crowded public spaces, installing more environmentally-friendly exhaust systems in new cars, phasing-out the use of leaded petrol, and encouraging people to walk, cycle or use public transport instead of personal motor vehicles.

As industrial activity, the use of fossil fuel-driven energy sources and the use of motor vehicles increases, more needs to be done to improve air quality in Australia. Ensuring that indoor areas are properly ventilated, researching into better fossil-fuel combustion techniques and promoting alternative energy sources are some measures that could be taken to improve this situation. Enhancing citizens' understanding of how individuals can make a difference to air quality and displaying a much stronger commitment to improving Australia's poor track record of greenhouse gas emissions are also needed.