Background: The toxicity of welding fumes depends on both chemical composition and ability to penetrate and deposit deeply in the lungs. Their penetration and deposition in the regions of the respiratory system is mainly determined by their size. Objectives: The knowledge of the size distribution of welding fumes is a crucial information towards the estimate of the doses of toxic compounds delivered into the respiratory tract. Methods: Particle number size distribution was continuously measured during different welding operations by means of a Fast Mobility Particle Sizer, which counts and classifies particles, according to their electrical mobility, in 32 size-channels, in the range from 5.6 to 523 nm, with 1s time resolution. Results: The temporal evolution of submicrometric particles (6-523 nm), nucleation mode particles (6-16 nm) and the fraction 19-523 nm before, during and after the welding operations performed with/without local exhaust ventilation are reported and extensively discussed. Before welding, nucleation mode particles represent about 7% of submicrometric particles; after about 40 s from the welding start, the percent contribution of nucleation mode particles increases to 60%. Total and nucleation mode particle concentrations increase from 2.1°—104 to 2.0°—106 and from 1.6°—103 to 1.0°—106, respectively. Conclusions: The temporal variation of the particle number size distribution across the peaks, evidences the strong and fast-evolving contribution of nucleation mode particles: peak values are maintained for less than 10 s. The implication of such contribution on human health is linked to high deposition efficiency of the submicrometric particles in the alveolar interstitial region of the human respiratory system, where gas exchange occurs.
Introduzione: La tossicità dei fumi di saldatura dipende sia dalla composizione chimica sia dalla capacità di penetraree depositarsi nei polmoni. La loro penetrazione e deposito nelle regioni del sistema respiratorio è determinataprincipalmente dalla loro dimensione granulometrica. Obiettivi: La conoscenza della distribuzione dimensionaledei fumi di saldatura è una informazione cruciale per la stima delle dosi di composti tossici veicolati nel tratto respiratorio. Metodi: La distribuzione granulometrica delle particelle è stata misurata in continuo durante differentioperazioni di saldatura mediante il Fast Mobility Particle Sizer, strumento che permette di contare e classificare leparticelle, secondo la loro mobilità elettrica, in 32 canali, nell’intervallo granulometrico 5,6-523 nm, con un tempodi risoluzione di 1 s. Risultati: Viene riportata ed ampiamente discussa l’evoluzione temporale delle particelle submicrometrichetotali (6-523 nm), delle particelle nel modo di nucleazione (6-16 nm) e nell’intervallo 19-523 nm,prima, durante e dopo le operazioni di saldatura effettuate con/senza ventilazione locale. Prima della saldatura, leparticelle nel modo di nucleazione rappresentano circa il 7% delle particelle sub micrometriche totali; dopo circa 40 sdall’inizio saldatura, il contributo percentuale di particelle nel modo di nucleazione aumenta fino al 60%. Le concentrazionedi particelle totali e nel modo di nucleazione aumentano da 2,1°—104 a 2,0°—106 e da 1,6°—103 a1,0°—106, rispettivamente. Conclusioni: La variazione temporale della distribuzione dimensionale delle particelleevidenzia il forte contributo e la rapida evoluzione delle particelle nel modo di nucleazione: i valori di picco vengonomantenuti per meno di 10 s. L’implicazione di tale contributo sulla salute umana è legata alla elevata efficienzadi deposizione delle particelle sub micrometriche nella regione alveolare interstiziale del sistema respiratorio umano,dove avviene lo scambio di gas.
Particelle submicrometriche in fumi derivanti da operazioni di saldatura e di fusione di leghe metalliche
AVINO P
;
2013-01-01
Abstract
Background: The toxicity of welding fumes depends on both chemical composition and ability to penetrate and deposit deeply in the lungs. Their penetration and deposition in the regions of the respiratory system is mainly determined by their size. Objectives: The knowledge of the size distribution of welding fumes is a crucial information towards the estimate of the doses of toxic compounds delivered into the respiratory tract. Methods: Particle number size distribution was continuously measured during different welding operations by means of a Fast Mobility Particle Sizer, which counts and classifies particles, according to their electrical mobility, in 32 size-channels, in the range from 5.6 to 523 nm, with 1s time resolution. Results: The temporal evolution of submicrometric particles (6-523 nm), nucleation mode particles (6-16 nm) and the fraction 19-523 nm before, during and after the welding operations performed with/without local exhaust ventilation are reported and extensively discussed. Before welding, nucleation mode particles represent about 7% of submicrometric particles; after about 40 s from the welding start, the percent contribution of nucleation mode particles increases to 60%. Total and nucleation mode particle concentrations increase from 2.1°—104 to 2.0°—106 and from 1.6°—103 to 1.0°—106, respectively. Conclusions: The temporal variation of the particle number size distribution across the peaks, evidences the strong and fast-evolving contribution of nucleation mode particles: peak values are maintained for less than 10 s. The implication of such contribution on human health is linked to high deposition efficiency of the submicrometric particles in the alveolar interstitial region of the human respiratory system, where gas exchange occurs.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.