A CLOSER LOOK AT AIR POLLUTION Humans drive cars, build factories and burn forests. All these activities - and many more - release gasses and particles into the air that can cause pollution including acid rain and smog. The pollutants can travel quickly on the wind, bringing problems to areas a long way from their source, often in different countries. Here are a couple of simple ways of looking closely at what’s actually in the air that you breathe. 1. Examining Particulates Particulates are tiny pieces of solid matter carried in the air. Some are from natural sources, such as volcanic ash, salt from the oceans, and pollen from plants. Others are man-made such as the soot produced from burning coal, oil and wood. Some particulates are very small and these are a particular problem as they can be drawn deep into the lungs, where they can cause breathing difficulties and put a strain on the heart. What to do... 1. Take some strips of white card about 15 cm long (you could use the unmarked side of old birthday cards) and make a hole at one end. 2. Smear the card with a thin layer of Vaseline or other petroleum jelly. 3. Thread string through the holes in the cards so that they are easy to hang up. 4. Suspend or tape the cards in different locations to see how many particles they capture. You could try: inside your house, outside your house, under a tree in the park, beside a busy road. 5. Check the cards after a couple of days or a week. How dirty have the cards become? Is there a difference depending on their location? Use a magnifying glass to examine the particles more closely. 2. Looking at Lichens Lichens are the crusty organisms that grow in inhospitable places such as on rocks and bricks. You can also find them on gravestones and the side of trees. They range in colour from grey-green to orange and red. Some lichens are very sensitive to air pollution, particularly to the sulphur dioxide gas that’s produced when fuels like coal and oil are burned. Only a few species can survive in areas of high pollution, so they act as an indicator of air quality. In severely polluted environments, only a couple of species will survive. As lichens only grow very slowly, even if a previously polluted area becomes clean, it will take a long time for the more delicate lichens to re-establish themselves. What to do... 1. Choose a location and closely examine any lichens that you can find there. 2. What type of lichens can you find? Lichens with leafy fronds are the most sensitive to pollution while crusty lichens the hardiest. 3. How many types can you see? The more types of lichen that can survive, the cleaner the air is. Have a look at the Natural History Museum’s website to compare leafy and crusty lichens. Go back