Tillandsia usneoides as biomonitor of air pollution.

T. usneoides is one of the most employed organisms for biomonitoring atmospheric metalsdue to its ability to accumulate and retain pollutants, including trace elements. In this article, we review the use of T. usneoides as biomonitor of atmospheric metals, as well as thedifferent types of biomonitoring, sample preparation methodologies and analytical techniques used in the studies performed in the last two decades. We also present the most important results of T. usneoides that have been obtained in different biomonitoring studies and geographical areas around the world. According to the results of these studies, T. usneoides isa sensitive and selective biomonitor for some metals, able to respond quickly to smallchanges in atmospheric composition, making it a suitable option for comparing sites or forbiomonitoring short-term events. However, it is necessary to validate its implementation with calibration curves made in the environment under study. In summary, there is an important opportunity area for the study of physiological parameters in T. usneoides as response of pollutants, which could be useful as biomarkers of exposure and effect.