XRD Technology Used for Air Quality Monitoring

Air quality is one of society’s major concerns for human health. There is a need for continuous monitoring of particulates especially in the submicron range. X-ray Diffraction (XRD) is one of the principal techniques for the analysis of powders and fundamental to identifying dangerous contaminents. A European project named Nanoair (REA FP7 222333) has been concluded successfully, its aim was to develop a mobile instrument for qualitative and quantitative analysis of breathable air.

Following Nanoair, another collaborative project named EnviroMonitor (REA FP7 286570 between Inel (France) the main coordinator, Comde, Briton, Camfil Farr and Ineris has been instigated to finish the engineering of the portable instrument. The goal of the project was to build a complete portable system that collects the dust, analyses it automatically to obtain particle sizes, carries out phase identification and quantification along with crystallites/microstrains and finally stores all data and results online and the samples locally for reference. The first prototype is currently being tested.

The dust sampling system pumps the ambient air and then filters to collect only the PM10, PM2,5 and lower size particles. It operates with a pumping flow of 2,3 m3/h. Data analysis is carried out by the Full Pattern Search-Match (FSPM) method. This automated software has been specially developed for this application based on the Rietveld analysis method for phase identification and quantification. The dust collection is performed continuously on a filter band for a 30 minute period of time. The filter band inserted in the system allows 2 weeks of continuous, onsite recording.

The results of the data analysis are compared to thresholds that had to be pre-defined and entered in the system to allow the release of an alarm if one or several thresholds are exceeded. A report is then generated gathering all the information and this is then stored locally.