Airborne silica levels in an urban area.

In order to evaluate the exposure levels of the general population we studied the concentrations of silica particles in the inhalable particulate fraction (PM10) in different meteorological-climate periods in an urban area of Rome. In order to determine the concentration and the granulometric spectrum of silica particles, PM10 sampled by a cascade impactor was analysed by X-ray diffractometry (XRD) and by scanning electron microscopy equipped with a thin-window system for X-ray microanalysis (SEM/EDX). Over the period September 2004-October 2005 the abundance of silica particles as evaluated by SEM/EDX ranged from 1.6 to 10.4% of the total PM10 particulate, with a weight concentration of free crystalline silica, evaluated by XRD, in the range 0.25-2.87 microg/m3. The mean diameter of silica particles ranged from 0.3 to 10.5 microm, with more than 87% of particles having a diameter of less than 2.5 microm. The correlations between SEM/EDX and XRD data seem to suggest that the airborne silica particles in the urban location studied were mainly in the form crystalline silica. A strong relationship was found between the meteorological-climate conditions and the concentration level of free crystalline silica. This result suggests that the Southern winds from the Sahara desert carry an important amount of silica particles into Mediterranean Europe.

[The effectiveness of measurements of chemicals and biological agents in the particulate matter of the workplace: the contribution dell'INAIL-CONTARP]. / L'efficacia delle misure di agenti chimici e biologici aerodispersi negli ambienti di lavoro: il contributo dell'INAIL-CONTARP.

Quality assurance of measurements is a crucial target for the laboratories interested in improving their analytical performances. To this aim, the Italian Workers' Compensation Authority (INAIL) has undertaken inter- and intra-laboratory net in the fields of chemical and biological agents measurements for workplaces risk assessment. Purposes and results of up to date experimental activities are summarized in this work.

[The "silica" component in the PM10 of an urban site]. / La componente "silice" nel PM10 di un ambiente urbano.

BACKGROUND: In vivo and in vitro toxicological studies have shown that the aged fracturated crystalline silica, which is a component of airborne particulate, exerts an important inflammatory action on airways. The evaluation of the concentration level of airborne crystalline silica in an urban area is an important research subject in order to determine the exposure levels of the general population. OBJECTIVES: The aim was to study the seasonal trend of the quartz (the most common form of crystalline silica) concentration levels in the particulate inhalable faction (PM10) in the urban area of Rome. METHODS: PM10, sampled by a cascade impactor, was analysed by scanning electron microscopy, equipped with a thin-window system for X-ray microanalysis (SEM/EDX) for qualitative analysis. Parallely the concentration levels of quartz in the particulate were determined by X-ray diffractometry (XRD) for quantitative analysis, using the NIOSH 7500 method (NIOSH, 1994). RESULTS: From September 2004 to October 2005 the abundance of silica particles, evaluated by SEM/EDX was in the range 1.6/10.4%, with a concentration level of free crystalline silica in the range 0.25/2.87 microg/mi. The equivalent diameter of silica particles ranged from 0.3 to 10.5 mircom, moreover, more than 87% of particles showed a diameter less than 2.5 microm. CONCLUSIONS: The correlations between SEM/EDX and XRD data seem to suggest that the airborne silica particles in the urban location studied consisted mostly of crystalline silica. Moreover, the data suggest the existence of a significant contribution of silica particles due to southwest wind carrying a fine dust from the Sahara desert to Mediterranean Europe.