Pollution is undesirable state of the natural environment being contaminated with harmful substances as a consequence of human activities so that the environment becomes harmful or unfit for living things; especially applicable to the contamination of soil, water, or the atmosphere by the discharge of harmful substances. In addition to the harm, either present or future and known or unknown, to living beings, pollution cleanup and surveillance are enormous financial drains of the economies of the world. Air pollution research is the subject of this volume.