Chapter 1 - Lichen-based index of atmospheric purity (IAP) for biomonitoring of air

Abstract

Lichen-based index of atmospheric purity (IAP), which was developed in the 1960s in Canada, is now used for biomonitoring of air quality in many parts of the world. IAP is applied in different environmental settings such as urban areas, peri-urban areas, rural areas, industrial areas, forested areas, and geothermal areas. The index can monitor air pollutants like SOx, NOx, and heavy metals such as Ni, Zn, Mn, Cu, Pb, Cd, and Cr. It also helps in mapping and zoning regions around pollution sources with a gradient. There are different formulae for IAP which is in practice worldwide but the two most common formulae are, companion factor (Q)-based, and frequency (F)-based. While the “F”-based IAP was used as a national guideline in Italy for monitoring gases about two decades ago, the “Q”-based index is recently used in a study associating asthma and air pollution in Algeria. The present work enlists 35 different applications of IAP in last 25 years across the globe. It is observed that the IAP formula is gradually evolving with many researchers now using modified and newer elements, for example, complementing lichen-forms–based environmental classification factor, used in Brazil. It is important therefore to be cautious in using and interpreting the index while comparing one study with other.