A CONTINUOUS, HIGH-RESOLUTION RECORD OF URBAN AIRBORNE-PARTICULATES SUITABLE FOR RETROSPECTIVE MICROSCOPIC ANALYSIS

This paper describes the use of a portable particle impactor (the Burk ard Spore Trap) for monitoring urban aerosols such that a continuous, permanent, high resolution record is obtained, periods of interest can be readily determined and retrospective analysis can be undertaken di rectly. Simultaneous use of two collection substrates allows that diff erent analyses (e.g. light microscopy, chemical analyses, digital imag ing) can be performed on almost identical samples over precisely defin ed time periods. Preliminary results are presented giving a few exampl es of the sort of studies possible using the approach. Comparison with the Enhanced Urban Networks' TEOM PM(10) data, suggest that the TEOM (measuring by mass) responds to a relatively small number of large par ticles and not the smaller, more numerous, and from a human health per spective more important size fractions (i.e. < 2.5 mu m). This is emph asised when studying trends in various size classes during a rain even t where the larger fraction (and TEOM) shows decreases due to ''washou t'' whereas finer fractions show little change in trends. Results also suggest that biological particulates (e.g. fungal spores) may form a significant fraction (> 20%) of the urban aerosol especially following rain events. The versatility of the sampler, coupled with its portabi lity and battery powering suggests great potential for the technique i n applications to a wide variety of particulate studies. Copyright (C) 1996 Elsevier Science Ltd