Local air pollution begins at home
Key text
This topic is sponsored by BHP.
Local air pollution is a major health threat. It ranges in scale from cigarette smoke in a house to the photochemical smog that can cover a city.
Fighting for breath
We all know that air pollution makes life miserable – but what exactly is it, and what can we do about it? We are not talking here about the greenhouse effect or the hole in the ozone layer (serious though those are), we are talking about local air pollution, the stuff most of us live in and breathe every day.
What is pollution?
'Air pollution' means that there is something in the air we don't want. The combination of gases which make up natural or 'fresh' air seldom do us any harm, and without the most important gas for us – oxygen – we could not live. The problem comes when unwelcome chemicals are added.
In Australia the main contaminants of outside air are
- carbon monoxide, nitrogen oxides and hydrocarbons from vehicle exhausts;
- ozone (generated when oxides of nitrogen and hydrocarbon compounds react in the presence of sunlight);
- sulfur dioxide (from the roasting of sulfur-containing mineral ores or from other industrial processes);
- microscopic particles (formed from most reactions involving combustion).
Not all pollution is caused by humans – the air around a large bushfire, or on the edge of an active volcano can be even more polluted than the worst city centre.
In some ways, the definition of air pollution is a bit like the definition of junk – 'something useful in the wrong place'. The things that pollute air may not be bad in themselves. Ozone, for example, is a real problem at street level, but in the stratosphere it protects us from ultraviolet rays. Lead is another example – it is a durable, easily worked metal that is ideal for waterproofing a roof, screening against X-rays, or even weighting a fishing line – but lead is very nasty when it gets into your bloodstream.
Where does pollution come from?
Some countries have a problem with polluted air blowing in from the neighbours – Norway has complained for many years about the dirty air from Britain's power stations blowing across the sea and poisoning its beautiful lakes with acid rain. In Australia we are luckier, because most of our pollution is 'home-made'. Not lucky because we have pollution, but because we can do something about it. By understanding the causes of air pollution better we will be able to improve things.
The biggest single source of air pollution in Australia is the car (Box 1: Cars). Next comes industry and then a heap of smaller sources like backyard incinerators, cleaning chemicals, paint fumes, and even furniture and carpets (Box 2: Indoor air pollution). Most of our local air pollution problems are caused by us – and by the machines and chemicals we use.
Indoor air pollution
Close the windows to keep the air pollution out? Well, maybe, but definitely not if you (or someone you share your home with) smoke indoors! When cigarette tobacco burns it gives off a particularly deadly range of substances, including carbon monoxide. You don't have to smoke yourself, just sharing a closed space with someone who is smoking is damaging – even though it may take many years for it to show up.
Open fires, kerosene fires, and gas fires can all cause problems if they are not properly ventilated. Carbon monoxide is again the problem here. Carbon monoxide is a fast-acting poison for all animals that have red blood cells (including humans). The gas gets into your bloodstream and attaches itself to the oxygen-carrying red cells and stops them working. Without oxygen your body cannot function properly, and it doesn't take much carbon monoxide to be a problem. As little as 10 parts per million (0.001 per cent) can cause headaches, tiredness and slow reflexes. You will die if you inhale more than 200 parts per million of carbon monoxide for more than a few minutes.
The future
Nearly all of us are affected by air pollution. The effects of continuous lifelong exposure to low levels of certain pollutants are still unknown. Many employers must now consider air quality as an important issue for their workers, and government agencies increasingly monitor it, while scientists research its effects. This area of environmental care is likely to become much more important in the future as we learn more about it.
Boxes
1. Cars
2. Indoor air pollution
Related Nova topics
Earth's sunscreen – the ozone layer
Quiet please! Fighting noise pollution
Posted August 1997.