Background Particulate matter, or particles which can be found in the air, may be classified as solids, gases or aerosols. Some of the solid material may be soot, ash, soil or dust. Much of the solid material comes from the burning of trash, fires, dust storms and soil erosion. The most prevalent gases are carbon monoxide and sulfur dioxide. These come from imcomplete combustion of gasoline, natural gas, burning of sulfur-containing fuels , and smelting and refining or ores.
Aerosols are insoluble particles suspended in a gas.
The particles are too small to be pulled to the earth by gravity and remain suspended in the air. Many of the garden and household aerosols are potentially dangerous because, if they are not dispersed by a fan or the wind, they can cause respiratory illnesses. Materials petri dishes, graph paper cut into circles the size of the petri dishes, vasoline, tape Procedure Tape a circle of graph paper to the bottom of the petri dish so that the squares can be seen from the top of the dish. Cover the bottom of the plate with a thin film of vaseline. Have students place half of the dishes inside in various locations around the classroom and the other half outside sheltered from rain.