“…Active moss biomonitoring, predominantly using the "moss bag technique", has been applied in air quality assessments of urban microenvironments (e.g., Cao et al, 2009;Adamo et al, 2011), where naturally grown bioindicators of air pollution, such as mosses and lichens, are not usually available. However, only a few active biomonitoring surveys have been performed on a large scale with extensive sampling grids over urban environments, e.g., across Girona and Salt, Spain (Rivera et al, 2011), Santa Cruz de Tenerife, Spain (Ares et al, 2011), and Warsaw, Poland (Orliński, 2002;Dmuchowski and Bytnerowicz, 2009).…”