1. Compare available particle counters to measure continuously concentrations and size distributions of fine and ultrafine particles in the urban atmosphere.
2. Assess the size distribution and elemental composition of respirable particles in different urban atmospheres in Germany, the Netherlands and Finland.

Expected achievements
The project is expected to produce significant improvements in our understanding on size distributions,
intercorrelations, and behaviour of fine and ultrafine particles in urban air in Europe and how to best measure
them. This will also enable future studies to address the question, which characteristics (size, number, elemental
composition) of respirable particles in ambient air determine their health effects.
Methods
Particle counters
The German Mobile Aerosol Spectrometer (MAS) consists of two different sensors covering different size
ranges. Particles in the size range from 0.01 5m to 0.1 5m are measured using a differential mobility analyzer
(DMA, TSI model 3071) in combination with a condensation nucleus counter (CNC, TSI model 3760).
Particles in the size range from 0.1 5m up to 3 5m are classified by a laser aerosol spectrometer (LAS, PMS
model LAS-X). In the Netherlands, similar equipment as in Germany will be used.
Electric Aerosol Spectrometer (EAS) used in Finland is based on the electric measurement principal similar to
the principle of EAA model 3030 of TSI, but significantly modified takin into account the needs of atmospheric
aerosol studies in urban and rural environment. EAS has an enlarged measurement range from 0.010 5m to
10 5m divided into fractions. All fractions are measured in parallel and simultaneously.
Other Measurements
In addition to the particle counters, the following measurements will be done: CPC (TSI 3022A), 24-hour
samples of PM10 and PM2.5 with impactors, metal composition of PM2.5 filters and continuous monitoring
of gaseous pollutants and weather.
Comparisons between different particle counters
The particle counters will be compared mainly running them side-by-side in ambient air conditions.
Measuring campaign of ambient aerosols
During the winter 1996-97, levels, gradients, and elemental composition of fine particles in urban sites in
Germany, the Netherlands, and Finland will be determined. In each location, ambient air quality will be
monitored at one site representing background urban levels of air pollution.