The mole fraction of argon in ambient dry air has been measured using gas phase chromatography calibrated with gravimetric gas standards prepared at the Laboratoire National de Métrologie et d'Essais. Different air samples, operators and gas standards were used to obtain a value of 0.9330 × 10 −2 mol mol −1 ± 0.0032 × 10 −2 mol mol −1 . This value is significantly different from the conventional value (0.917 × 10 −2 mol mol −1 ) used in the 81/91 formula of the Comité International des Poids et Mesures (CIPM) (Davies 1992 Metrologia 29 67-70) for the determination of air density during comparisons of mass standards.This value confirms the result obtained by the Korea Research Institute of Standards and Science, which found a concentration of 0.9332 × 10 −2 mol mol −1 ± 0.0006 × 10 −2 mol mol −1 by mass spectrometry in 2004.This new value explains the difference between the CIPM formula method and the artefact method used for the determination of air density.

Résumé. Dans le domaine de la santé, sans que le professionnel voire le patient en ait pleinement conscience, la qualité de fonctionnement des dispositifs médicaux et scientifiques utilisés concourt à la qualité des soins. Pourquoi ? Comment la maîtrise, par les professionnels de la santé, de la fonction métrologie participe à l'évaluation des risques et à leur réduction, à la prévention d'accident ou de mauvais diagnostic ? Des éléments de réponse sont développés par les conférenciers à la lumière de leur expérience au sein d'une entreprise de services dans les domaines de la métrologie et santé. Abstract.In the field of health, without professional and even the patient has full consciousness, the quality of medical devices used contributes to the quality of care. Why? How the control, by health professionals, of the Metrology concept participates in the assessment of risks and their reduction, prevention of accident or wrong diagnosis? Answers are developed by the speakers in the light of their experience within a service company in the areas of metrology and health.

Air quality is a major social issue. Among the many compounds that could be harmful for Human health, Volatile Organic Compounds (VOCs) belong to the most monitored and regulated pollutants. In France, the monitoring of VOCs in ambient air is carried out by sampling air onto activated carbon cartridges during a given period (7 or 14 days) by the "Associations Agréées de Surveillance de la Qualité de l'Air" (AASQA). This method consists of two parts: sampling and analysis. To ensure the reliability of their measurement results, laboratories must guarantee the traceability of their analysis and validate their analytical protocols: this can be done by the use of Certified matrix Reference Materials (CRMs). However, in France, no reference materials are available for the measurement of VOCs in air onto sorbent tubes. Therefore, LNE developed a system for loading benzene, from a gaseous reference material onto Carbopack X tubes. These CRMs could be used for the calibration of analytical systems and for the evaluation of analytical laboratories. After this development phase, LNE has organized a proficiency testing between three expert laboratories, based on the implementation of these materials: it shows no significant differences between analyzed masses and loaded masses for each participating laboratories.