These data files are periodic (15 minutes) measurements of the concentration of nitrogen dioxide and particulate matter in the air for the monitoring station at Market Street, Hebden Bridge. The units are measured in micrograms per cubic metre (PM2.5 and PM10 are fine particulate matter). Each file shows data for a whole year, the file uses the name R3 for the Air Quality Station 3. The data has been checked and calculations made on ...