Differences among black smoke, PM10, and PM1.0 levels at urban measurementsites

In Amsterdam, the Netherlands, we measured airborne particulate matter (PM) during winter 1998-1999, taking daily average measurements at an urban bac kground site, at a busy street, and at a motorway. Comparison of blade smok e, PM10, and PM1.0 levels showed that daily averages were highly correlated over time. Median daily concentrations were elevated at sites affected by traffic. The highest increase relative to the background in median daily co ncentration was noted for black smoke at the motorway (300%), whereas for P M10 and PM(1.)0 the increase was only 37% and 30%. These results indicate t hat mass measurements of ambient particulate matter underestimate the expos ure to particles generated by traffic.