Dr. Stephanie Bell is a specialist in humidity measurement, standards and calibration, with more than 30 years’ experience in the metrology area. She has worked on humidity measurement techniques, primary humidity standards for various humidity quantities, trace moisture in gases, moisture content of materials, water vapour flux (skin water loss), water vapour pressure data and calculations, and uncertainty evaluation. Her work has addressed applications such as meteorology and climate, fuel cells, and hydrogen for vehicles. Recent interests include research into accurate air temperature measurement, and the development of humidity calibrations in non-air gases and gas mixtures and at above-atmospheric pressures, especially for energy-related gases. Stephanie has chaired national and international committees on humidity, she leads NPL's humidity training course, and she has worked extensively as an assessor for laboratory accreditation in the UK and wider. She has worked on problem-solving consultancies and projects for various humidity applications and has a wide range of published papers, reports and guides on humidity and moisture, measurement uncertainty, and related subjects.