Th. Tuch

Concentrations of ultrafine, fine and PM2.5 particles in three European cities

Total number concentrations, number concentrations of ultrane (0.01}0.1 m) and accumulation (0.1}0.5 m) particles, as well as mass concentration of PM particles and blackness of PM lters, which is related to Black Smoke were simultaneously monitored in three European cities during the winter period for three and a half months. The purpose of the study was to describe the di!erences in concentration levels and daily and diurnal variations in particle number and mass concentrations between European cities. The results show statistically signicant di!erences in the concentrations of PM and the blackness of the PM lters between the cities, but not in the concentrations of ultrane particles. Daily PM levels were found to be poorly correlated with the daily total and ultrane number concentrations but better correlated with the number concentration of accumulation particles. According to the principal component analysis airborne particulate pollutants seem to be divided into two major source categories, one identied with particle number concentrations and the other related to mass-based information. The present results underline the importance of using both particle number and mass concentrations to evaluate urban air quality. 2001 Elsevier Science Ltd. All rights reserved.

Variation of particle number and mass concentration in various size ranges of ambient aerosols in Eastern Germany

Abstract There is an ongoing debate on the question which size fraction of particles in ambient air may be responsible for short-term responses of the respiratory system as observed in several epidemiological studies. However, the available data on ambient particle concentrations in various size ranges are not sufficient to answer this question. Therefore, on 180 days during the winter 1991/92 daily mean size distributions of ambient particles were determined in. Erfurt, a city in Eastern Germany. In the range 0.01–0.3 μm particles were classified by an electrical mobility analyzer and in the range 0.1–2.5 μm by an optical particle counter. From the derived size distributions, number and mass concentrations were calculated. The mean number concentration over this period of time was governed by particles smaller than 0.1 μm (72%), whereas the mean mass concentration was governed by particles in the size range 0.1–0.5 pm (83%). The contribution of particles larger than 0.5 μm to the overall number concentration was negligible and so was the contribution of particles smaller than 0.1 μm to the overall mass concentration. Furthermore, total number and mass concentrations in the range 0.01–2.5 μm were poorly correlated. The results suggest that particles larger than 2.5 μm (or even larger than 0.5 μm) are rare in the European urban environment so that the inhalation of these particles is probably not relevant for human health. Since particle number and mass concentrations can be considered poorly correlated variables, more insight into health-related aspects of particulate air pollution will be obtained by correlating respiratory responses with mass and number concentrations of ambient particles below 0.5 μm.

Comparability of three spectrometers for monitoring urban aerosol

Abstract The comparability was tested of three aerosol “spectrometers”, used in a program for monitoring the spectra of fine and ultrafine particles in three European cities. Droplets of sebacate, solid ammonium sulfate and agglomerates of elemental carbon were used in the tests, representing the major chemical and structural types of particles encountered in urban aerosol. Particles in the ultrafine range (10–100xa0nm) are sized by electrical mobility (SMPS, DMPS and EAS) and the “spectrometers” gave very similar size distributions for these aerosols. The integrated number concentrations were on average within 20% of the directly measured total number concentrations. Particles with a size between 0.1 and 2.5xa0μm, in which most of the volume/mass is concentrated, are being differently classified in the three “spectrometers”, respectively, with a low- and a high-flow LAS-X, and field charging in the EAS. The agreement between the three instruments in this size range was less good, which was partly caused by signal overload in the high-flow optical sizer, which was solved using a larger threshold. A complication occurred with the elemental carbon, which was composed of highly agglomerated entities. Particles, sized by the mobility instrumentation as being in the range of 100–400xa0nm, were not detected by the optical sizers. Volume (spectra) for ammonium sulfate deduced from the number spectra were compared with the mass (spectra) obtained with cascade impactors. The comparison was good for the LAS-Xs; the EAS overestimated volume/mass.

Design, operation and performance of whole body chambers for long-term aerosol exposure of large experimental animals

Four large whole-body exposure chambers, 19 m3 in volume, are available at this research centre for studies on the effect on lungs following long-term exposure to particulate air pollutants. Each chamber is designed to house up to five beagle dogs according to the floor space requirements for dogs, thus up to 20 dogs are available for one exposure experiment. Clean air is supplied by an air conditioning system with particle, charcoal and adsorbent filters. A horizontal air flow design provides uniform distribution of aerosol, temperature and relative humidity in the chambers with long-term stability. Data acquisition is fully automated. Alarms are available to warn of deviations from airflow settings and aerosol mass concentration. The design of the chambers and their performance during a 290 day exposure are described in this paper.

Long-term exposure of dogs to a sulphite aerosol: I. Rationale and design parameters

Abstract Eight Beagle dogs were exposed to a sodium bisulphite aerosol at a concentration of 1 mg m −3 for a period of 290 days. This paper summarizes the design, the facilities and the exposure conditions of the exposure experiment.

Estimation of the deposition of polydisperse hygroscopic aerosol particles in the respiratory tract

Abstract A method is described to estimate the total and regional deposition of polydisperse aerosol particles from data on the deposition of different salt aerosol particles described in literature (Ferron et al. , J. Aerosol Sci. 1988, 19, 611) and own calculations. This method is applied to estimate the regional deposition of a Na 2 S 2 O 5 aerosol in the human respiratory tract.

Intercomparison of particle size spectrometers

METHODS The performance to assess the particle size distr ibut ion of a polydisperse aerosol of four low pressure impactors (LPI) and three optical particle counters (OPC) was studied. The ins t rumen t s used are listed in table 1. The polydisperse aerosol was produced by nebulizat ion of an aquaeous solution of sodiumbisulfite. A uniform mass concentrat ion of 0.5 m g m -3 was main ta ined in a 20 m 3 chamber vent i la ted wi th a flow rate of 320 m 3 h 1. The concentrat ion varied less t h a n 4 % as indicated by an automat ic mass sensor (TSI Microbalance Model 5000) and filter samples. The mass of the particles sampled with the impactors was evaluated by PIXE analysis of sulfur (Proton Induced X-ray Emission; Hietel and Tschiersch, 1988) and gravimetry as indicated in table 2 and figure 1. The four impactor samples were t aken wi thin a 3 hour period.