DEMONSTRATION OF A NEW COUNTING INSTRUMENT FOR MEASURING AMBIENT PARTICLE NUMBER DISTRIBUTIONS RESULTING FROM ROAD TRAFFIC

Studies of the impact of fine and ultrafine particles on health have gained significant importance in recent times. Research suggests that the number concentration of these fractions may be far more significant for health than their mass concentration. Currently, many monitoring instruments, for example, the TEOM and Partisol, are based on particle mass. Emissions from diesel vehicles in particular release high number concentrations of particles of size typically in the ultrafine region. This work reports on a newly developed real-time particle counter and preliminary results of its application are presented. The instrument is based on light scattering & condensation nucleus techniques to count and size particles from 10um down to 10nm. Initial results from laboratory evaluation of the instrument and real-time measurements of urban atmospheric particles are presented in this paper. Measurements of particle concentrations have been made at roadside and background sites in Bedford. The roadside site is located adjacent to free flowing traffic. The background measurements have been conducted at a roof top site within Bedford. The number distributions of the particles at these selected sampling sites are examined in terms of meteorological parameters and traffic sources. For the covering abstract see ITRD E122175.