‎"‎The control of air pollution is one of the principal areas of pollution control‎,‎ along with wastewater treatment‎,‎ solid‎-waste management‎,‎ and hazardous‎-waste management‎.‎ Air is considered to be polluted when it contains certain substances in concentrations high enough and for durations long enough to cause harm or undesirable effects‎.‎ This book discusses the operation and maintenance of air pollution control equipment and explores the problems connected with their use‎.‎‎"‎