title: X-ray fluorescence--an international calibration method.
mesh_terms: D000388:Air / Q000032:analysis; D000397:Air Pollution / Q000032:analysis; D003906:Developing Countries; D005374:Filtration; D005453:Fluorescence; D008628:Mercury; D008722:Methods; D009757:Nylons; D009942:Organometallic Compounds; D011827:Radiation; D013458:Sulfur Dioxide / Q000032:analysis*
chemical_list: D009757:Nylons; D009942:Organometallic Compounds; D013458:Sulfur Dioxide; D008628:Mercury