PIXE analysis of Tillandsia usneoides for air pollution studies at an industrial zone in Central Mexico

In order to find out if there is a relation between atmospheric particulate matter composition and human health effects, metals and other elements measurement are performed. Analysis of atmospheric aerosols collected in filters is the usual method to achieve this task. Biological monitors provide an advantageous alternative way of sampling, since there is no need of special sampling devices, and accumulation time can be as long as desired. In this study, Tillandsia usneoides a reliable air pollution biological monitor that occurs naturally throughout Mexico was used to monitor air quality of Tula-Tepeji corridor at central Mexico. This area is considered critical zone because of atmosphere contaminants high concentration. Some biomonitors were transplanted from a clean environment to four sites at the Tula corridor. Plants samples were collected every two weeks from February to April 2008. PM₁₀ sampling in filters was also performed simultaneously at three locations where T. usneoides was transplanted, for a comparison. Chemical composition was determined by PIXE. Results showed that T. usneoides incorporates anthropogenic elements reaching maximal levels after 6 to 10weeks approximately. Since results obtained with biomonitors agree with those obtained with aerosol filters, T. usneoides could be employed as a first approximation to provide insights of the atmospheric pollution level previous to a detailed study using filters.