Dissertation

Προσδιορισμός των ρυθμών εκπομπής και αντίστοιχης δόσης στο ανθρώπινο αναπνευστικό σύστημα από προσομοίωση διαφόρων πηγών αεροζόλ σε εσωτερικούς εργασιακούς χώρους

Serfozo, Norbert

2017

Overview

The presented doctoral dissertation deals with the estimation of emission rates from varines acrosol sources, which may occur in a wide range of indoor workplace environments. Moreover, substantial increase in particle number and mass concentration may lead to high exposure levels of possibly harmfial airborne contaminants. Thus, respiratory protection and human dose are also essential parts of this research. In the first part of Chapter 4, particle number concentration and size distribution along with PM and TVOC were measured during emissions from painting materials (turpentine oils) inside an indoor microenvironment (laboratory room of 54 m3). New particle formation events were observed in all 10 experiments. The nucleation events lasted on average less than one hour with an average growth rate 33.9 ±9.1 nm/h and average formation rate 21.1 8.7 cm-3s-1. After the end of the nucleation event, a condensational growth of indoor particles followed with average growth rate 11.6 +2.8 mm/h and duration between 1.4 and 4.1 h. High concentrations up to 3.24 ppm were measured for the indoor TVOC concentrations during the experiments. High nucleation rates indoors were observed in conjunction with high TVOC concentrations originating from painting materials which resulted to high exposure concentration levels of particle number concentration The next part of this study evaluates the nanoparticle emissions from laser printers in a print room (PR) and an office. Printing was identified as the most significant indoor source of nanoparticles (100 nm) resulting in a substantial increase of indoor PN concentration in the PR during the workdays. Average particle concentration during opened hours was measured to be 5.4 × 103 #/cm3 and similarly, as it was observed in the chamber study, printers startup on any given day was characterized by a sharp increase in particle concentrations (on average 4.4 × 105 #cm3). Printer from the PR examined in a chamber (7.6 m3) was generating nanoparticles (vast majority 50 nm with mode on ~15 mm) primarily during cold startup (1.9 × 104 to 1.6 x105 cm2). Dust resuspension may significantly contribute to increased mass concentration in an indoor environment. Therefore, PM and number concentration were measured during walking experiments inside a laboratory. The different dust loadings were used (25, 35, 5, 1 g/m2) in order to evaluate the impact of surface loading on the indoor PM mass concentration and on the resuspension rate. Moreover, the experiments involved two different walking patterns (rectangular and line). The average resuspension rate was calculated to be equal to 10-2 - 10-3 h-1. No impact on suspension rate was observed for different walking patterns or walking speed. On the other hand, the measured mass concentration inside the room was increased when using higher dust loading on the floor The objective of the last part of Chapter 4 was to determine the emission rates from two are welding processes (SMAW and TIG) and cutting processes in a simulated confined workspace of experimental chamber. All 3 investigated processes generated high particle member concentrations ranging from 24 to 3.6 106 #/cm3 and were the highest during TIG welding. Among all 3 processes, PM10 from cutting reached the highest mass concentrations (11 and 22 mg/m3), while SMAW had the highest contribution of fine particles (~4.1 mg/m3), consisting mostly of PM1-2.5.Chapter 5 deals with penetrations and the most penetrating particle size (MPPS) of 47 mm filters from CE-marked filtering facepiece respirators (FFRs) These were then compared to identical FFR models tested in manikin-based chamber tests. These two experimental methods were in good agreement (R2-0.91). Penetrations were evaluated size-selectively using 9 sizes of charge-neutralized monodisperse aerosol (20-400mm CMD). Comparison of the penetrations at MPPS from all the examined filters and FFRa showed within-respirator variations in all three filtering classes. The MPPS in this study was found to be in the range of 25-65 am (CMD) in all measurements. It is concluded that the EN 149 method underestimates particle penetration (especially for particles <100 mm) due to the inadequate penetration test method for respirator certification Human dose from aforementioned aerosol sources was assessed in ExDoM2 model and the results are presented in Chapter 6. During emissions from painting materials, the average increase of total dose represented 4.6 and 1.3-fold at emission and post-emission period, respectively, compared to the exposure dose from BC Increase of total dose in the PR represented 13.4 and 1.2-fold at printers startup and printing. respectively. Cumulative deposited and retained dose were also estimated for 4 different scenarios for resuspended dust, and arc welding. Results revealed that: (1) in both emission cases, the find scenario staying in the polluted workspace for the entire time period without a use of FFR, was the \"worst case' scenario; and that (2) It would be more beneficial in respect to total deposited dose if the exposed simulated subject not wearing FFR st the duration of emission, would leave the polluted workspace immediately after the end of emission. Due to very small contribution of fine particles in the resuspended dust, only -4% of total dose were deposited in the thoracic region. On the company. retained dose in the thoracic region was the highest for arc welding processes (~20%).

• Publisher: ProQuest Dissertations & Theses
• Subject: Aerodynamics / Air pollution / Atmospheric aerosols / Brownian motion / Chemical reactions / Dosimetry / Dust / Emissions / Flow velocity / Gases / Indoor air quality / Larynx / Lungs / Mathematical functions / Nanoscience / Outdoor air quality / Particle size / Respiratory system / Stainless steel / VOCs / Volatile organic compounds
• ISBN: 9798310191969