Air pollution has been recognised as the worlds top problem in many strategic environmental policies. However, it is still inadequately corroborated by regulatory monitoring due to the balance between costs and practicable constraints. The variability in air pollution patterns additionally emphasises a need for feasible approaches to extensive screening of pollutants. To achieve highly temporally and spatially resolved measurements, biomonitoring, i.e., the use of living organisms to determine changes in the environment has been utilised in the investigating of a complementary method to regulatory measurements. The book Biomonitoring of Air Pollution Using Mosses and Lichens: A Passive and Active Approach ‒ State of the Art Research and Perspectives aims to give reviews of research over the last decade of the most recommended organisms for monitoring airborne inorganic and organic pollutants. Naturally growing mosses and lichens have been used as passive biomonitors of long-term atmospheric deposition of the pollutants across remote areas. To overcome scarcity of these biomonitors in anthropogenically devastated areas, an active biomonitoring approach has been investigated. Specifically, the use of moss and lichen bags represents a convenient technique for easily performed biomonitoring of short-term and small-scale pollutant distribution, especially in urban and industrial areas. As a new direction in biomonitoring, magnetic properties of the biomonitors have been investigated as a valuable proxy for ambient particle pollution. This book moves beyond the attempt to promote biomonitoring as an effective approach for screening air quality that should be considered for implementation into laws and regulations against air pollution. Finally, the authors review the latest research in the field of air pollution biomonitoring, which is vital for everyone engaged in solving environmental issues.