A project has been undertaken to carry out a long term study on atmospheric air pollution in Chile using biomonitors. Samples
of different species of lichens were collected in clean areas (native forest), analyzed and transplanted to the Santiago Metropolitan
Area. In addition, samples of Tillandsia recurvata were collected in the Metropolitan Area for comparison purposes. The preparation of the samples was done under controlled,
cryogenic conditions and analyzed by neutron activation analysis and solid sampling atomic absorption spectrometry. As part
of the routine QA/QC procedures, the analytical laboratories, have participated in intercomparison runs organized by the IAEA
for the determination of trace and minor elements in two lichens samples. The present paper describes the activities carried
out within the framework of this project.