ASSESSING DAILY INTAKE OF INDOOR AIR POLLUTANTS FROM 3D PRINTING

The scientific community is increasingly focusing on indoor air quality (IAQ) more than ever, driven by on-going research and fresh perspectives including development of 3D technologies. Exposure dose (EDa) resulting from inhalation of indoor air pollutants emitted by 3D printers were calculated in this study. The consideration of emissions from 3D printers is based on experimental data, primarily sourced from reviewed literature. However, this research also includes some experimental values, excluding the background levels of these pollutants. Experiments were conducted using several 3D printers available (Zortrax M300 Dual) to compare the indoor air pollutants generated and their concentrations with information gathered from earlier research. In the experiments, filaments containing ABS (acrylonitrile, butadiene, and styrene copolymer material, commonly used for 3D printing) were utilized. EDa values of styrene, toluene, formaldehyde, and acetaldehyde for 8-hour and 12-hour shifts for average and maximal (reported) concentrations were calculated based on the available experimental and literature data. The average concentrations of these pollutants were determined by calculating the arithmetic mean, which incorporated concentration values obtained from previous research and experimental data collected within this study. It was concluded that further investigation should focus on aerial concentrations of styrene generated during 3D printing. Calculated EDa for styrene from several studies exceeded the recommended guidelines for Tolerable Daily Intake (TDI) set by the World Health Organization (WHO) by at least 35%. Further exploration is imperative to incorporate additional pathways of indoor air pollutant exposure, such as skin contact and ingestion.  This comprehensive approach will provide a more thorough understanding of the overall health risks associated with indoor air quality during 3D printing

MULTIPLE PATH PARTICLE DOSIMETRY MODEL CONCEPT AND ITS APPLICATION TO DETERMINE RESPIRATORY TRACT HAZARDS IN THE 3D PRINTING

The Multiple Path Particle Dosimetry (MPPD) model is computer software that estimates and visualizes the deposition, clearance, and retention of particles in the respiratory tract systems of humans, rats, and other species. The mathematical model provides a broad spectrum of settings and input options. This research aims to explore the MPPD model concept and determine the deposition fraction (DF), clearance, and retained mass in the human respiratory tract (HRT) based on the geometric mean diameter (GMD) and mass concentration (MC) of particulate matter (PM) emitted during the 3D printing process. We used the real-time air sample data collected during the 8-hour working shift in the 3D printing office. Ultrafine PM deposits mainly in lungs (56%), fine PM mostly deposits in the upper respiratory tract (URT) (41%) and lungs (39%), but coarse PM mostly deposits in the URT (81%). The biggest DF in lower respiratory tract is ultrafine PM (487 μg), the smaller DF is coarse PM (185 μg) and the smallest DF is fine PM (123 μg). The biggest DF in lung for all PM - lower lobes (fine PM - 60%, ultrafine PM, coarse PM - 61%). In a model, where exposure was 5 hours a day, five days a week, during one month, followed by one year of post-exposure period, it was shown that retained mass in the tracheobronchial (TB) region was 1% for ultrafine and coarse PM each, 2% for fine PM, and 55% for all PM in the pulmonary region. The MPPD software is an easily accessible and valuable tool for assessing the impact of PM on the HRT. Particulate matter decreasing in diameter, tend to deposit mostly in the deeper levels of HRT. Tracheobronchial region clearance is more rapid than pulmonary region clearance. Potentially for persons using the 3D-printer regularly the worst health impact could be associated with smaller size of PM, due to tendency deposit mostly in pulmonary region where the clearance rate is slower

Number of fine particles’ and their mass concentration : Comparison of emission of new printing technology versus traditional laser technology

Funding Information: Printers for use in this study were supplied by RF Serviss company. Publisher Copyright: © 2021 Linda Paegle, Žanna Martinsone, Ivars Vanadziņš, Ilona Pavlovska, Lāsma Akūlova.For many years the printers have been essential part of our offices and exposures from various printing technologies have been widely researched. The main objective of this study was to compare emitted number and mass of fine particles from laser printers and new Micro Piezo technology ink jet printers during the printing process and one hour afterwards as these emissions have potential for negative health effects. Air samples were taken with the particle size spectrometer for real-time ELPI+, Dekati (air flow rate 10 l/min). Measurements were taken ~0.5 m from the printers: one hour before the test, during printing and one hour afterwards. Similar class black&white (b/w) and colour printer of each technology were tested. Each printer performed a 10-page and a 100-page test according to ECMA 328-1 Standard [1]. During laser printer tests from 8324 to 19943 pt/cm 3 fine particles were determined on printing phase from b/w and colour printers. Ink jet (Micro Piezo) printers produced less: from 3239 to 5247 pt/cm 3. One hour after the printing phase for both types of laser printers’ there were 54722 to 152351 pt/cm 3 particles in air and 4270 to 9579 pt/cm 3 particles for ink jet printers. Detected particle mass differences was insignificant: in range of 0.002 to 0.012 mg/m 3 for laser printers and 0.002 to 0.019 mg/m 3 for ink jet printers. Micro Piezo technology printers emitted mass particles were with bigger median size μm. The highest number of particles was observed one hour after the printing for both tested printer technologies. Laser printers’ emitted 2.5 to 3.8 times more particles in printing phase and 12.8 to 15.9 times more after printing phase. Particle mass in mg/m 3 was detected in the size range 6nm - 2.5 μm with no significant mass differences.publishersversionPeer reviewe

Sola-gēla pārklājums uz emaljēta leģētā tērauda

doi: 10.7250/msac-2018-0010publishersversionPeer reviewe

Indoor Air Radon Concentration in Premises of Public Companies and Workplaces in Latvia

Funding Information: This study was partly financially supported by IAEA Technical Cooperation project RER/9127. Funding to pay the Open Access publication charges for this article was provided by the Institute of Occupational Safety and Environmental Health (Riga Stradins University). Funding Information: Funding: This study was partly financially supported by IAEA Technical Cooperation project RER/9127. Funding to pay the Open Access publication charges for this article was provided by the Institute of Occupational Safety and Environmental Health (Riga Stradins University). Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland.Considering the multitudes of people who spend their time working indoors in public premises and workplaces, it is worth knowing what their level of exposure is to natural radioactive radon gas, the second most widespread and dangerous carcinogen for lung cancer development after cigarette smoking. This state‐level study covered most of the territory of Latvia and conducted 941 radon measurements with Radtrack2, placed for 4–6 months in the premises of public companies, educational institutions, medical care institutions, etc. The study found that 94.7% of samples did not exceed the national permissible limit (200 Bq/m 3), the level at which preventive measures should be initiated. The median value of average specific radioactivity of radon in these premises was 48 Bq/m 3 (Q1 and Q3 being 27 and 85 Bq/m 3), which is below the average of the European region. Slightly higher concentrations were observed in well‐insulated premises with plastic windows and poorer air exchange, mostly in schools (59 (36, 109) Bq/m 3) and kindergartens (48 (32, 79) Bq/m 3). Industrial workplaces had surprisingly low radon levels (28 (16, 55) Bq/m 3) due to strict requirements for air quality and proper ventilation. Public premises and workplaces in Latvia mostly have low radon concentrations in the air, but more attention should be paid to adequate ventilation and air exchange.publishersversionPeer reviewe

Comparison of biological markers in aerosol-weighed workplaces

Funding Information: Funding information This work was supported by ESF project “The development of up-to-date diagnostic and research methods for the risks caused by nanoparticles and ergonomic factors at workplaces” (Agreement No. 2013/0050/1DP/1.1.1.2.0/13/ APIA/VIAA/025). Publisher Copyright: © 2019, The Author(s). Copyright: Copyright 2019 Elsevier B.V., All rights reserved.Airborne particulates present a potential hazard to health in a variety of indoor workplaces, from offices to the manufacturing floor. Dust and aerosols are two of the most common occupational risk factors in the workplace worldwide. It is very important to understand when it is sufficient to describe dust exposure only by given mass concentration that dust particles could be in the nanosized range in the workplace air even for brief exposures, such as welding aerosols. The main objective was to assess total dust and nanoparticle concentrations in the selected workplaces and to evaluate their impact on workers’ health. This project describes nanoparticle concentrations and their potential impact on workers’ health considering the exposure levels in three workplaces. Industrial and non-industrial environments have been included in the project. The office environment was used as an indicator for the background level of comparison with the metalworking and woodworking industries for measurements of dust particles including the nanoscale particles (> 100 nm). Fraction size of the samples according to a dispersity of > 10 μm, 0.25–10 μm, < 0.25 μm, and 1–100 nm was analysed in order to describe the particles’ chemical composition at the different stages. The worst working conditions (the smallest particles, 12 nm), the highest total dust concentrations, and the lowest difference between total inhalable particle and nanoparticle concentrations were detected among woodworkers. These findings provide a basis on how to evaluate nanoparticle exposure and its impact on workers’ health because the highest immune cell counts and relatively high IL-6 expression were observed among woodworkers compared with the other groups. The data show a negative tendency of nanoparticle exposure concentrations on workers’ health based on the increase of inflammatory processes and damage to airway epithelial cell functionality.Peer reviewe

The effect of different workplace nanoparticles on the immune systems of employees

Publisher Copyright: © 2017, The Author(s). Copyright: Copyright 2017 Elsevier B.V., All rights reserved.Currently, nanoparticles are widely present in the environment and are being used in various industrial technologies. Nanoparticles affect immune functions, causing different immune responses. The aim of the current study was to evaluate several cytokines, interleukin (IL)-1b, IL-6, IL-8, tumour necrosis factor-a (TNF-α), interferon-γ, adhesive molecule sICAM-1, macrophage inhibitory protein 1a (MIP1a) and secretory immunoglobulin A, in nasal lavage fluid and in the peripheral blood of healthy subjects exposed to workplace nanoparticles. Thirty-six employees from three different environments were examined: 12 from a metalworking company, 12 from a woodworking company and 12 office workers. The nanoparticles in the different workplaces were detected in the air in the immediate vicinity of the employees. The particle number concentration and surface area values were significantly higher in the workplaces of the metal- and woodworking industries, but concentrations of mass were lower (the measurements were performed by an electrical low-pressure impactor ELPI+). Energy dispersive X-ray spectroscopy (EDS, an attachment to a high-resolution SEM) was used to provide elemental analysis or chemical characterization of the dust particles in a low-vacuum field-free mode operating at a potential of 15 kV spot 3.0. The technique used provided quantitative and spatial analyses of the distribution of elements through mapping (two to three parallel measurements) and point analysis (four to five parallel measurements). Samples from the metal industry contained more ultramicroscopic and nanometric particles, e.g. toxic metals such as Zn, Mn and Cr, and fewer microscopic dust particles. The nasal lavage and peripheral blood were taken at the beginning and the end of the working week, when immune indices were measured. Our data showed a statistically significant increased level of the pro-inflammatory cytokine TNF-α in serum in both exposed groups compared with office workers as well as a higher level of TNF-α in workers from the woodworking company compared with the metalworking employees. We found an elevated level of IL-6 in the exposed groups as well as an elevated level of IL-8 in the nasal lavage in woodworking employees after work.publishersversionPeer reviewe

In vitro impact preliminary assessment of airborne particulate from metalworking and woodworking industries

Funding Information: This work was supported by ESF project “Development of up-to-date diagnostic and research methods for the risks caused by nanoparticles and ergonomic factors at workplaces” Agreement No. 2013/0050/1DP/1.1.1.2.0/13/ APIA/VIAA/025. Publisher Copyright: © 2021, The Author(s).Inhalation is the main route of exposure to airborne pollutants. To evaluate the safety and assess the risks of occupational hazards different testing approaches are used. 3D airway epithelial tissues allow to mimic exposure conditions in vitro, generates human-relevant toxicology data, allows to elucidate the mode of action of pollutants. Gillian3500 pumps were used to collect the airborne particulate from woodworking and metalworking environments. EpiAirway tissues were used to model half working day (4 h), full working day (8 h), and 3 working day exposures to occupational pollutants. Tissue viability was assessed using an MTT assay. For preliminary assessment, RT-qPCR analyses were performed to analyze the expression of gelsolin, caspase-3, and IL-6. Tissue morphology was assessed by hematoxylin/eosin staining. An effect on the proliferation of lung epithelial cell line A549 was assessed. Acute exposure to workspace pollutants slightly affected tissue viability and did not change the morphology. No inhibiting effect was observed on the proliferation of A549 cells. Preliminary analysis showed that both types of particles suppressed the expression of gelsolin, with the effect of metalworking samples being more pronounced. A slight reduction in caspase-3 expression was observed. Particles from metalworking suppressed IL-6 expression.publishersversionPeer reviewe

Assessment of Occupational Exposures in the 3D Printing: Current Status and Future Prospects

3D (three-dimensional) printing technologies are widespread and rapidly evolving, creating new specific working conditions, and their importance has been highlighted by increasing publications in recent years. The report provides a compilation of current information on 3D technologies, materials, and measurements, considering the determination of the potential actual exposure dose of chemicals through airborne inhalation and dermal exposure, including workers’ exhaled breath condensate and urine data. Noninvasive assessment methods are becoming increasingly popular, as they are painless, easy to perform, and inexpensive. Investigation of biomarkers reflecting pulmonary inflammation and local and systemic oxidative stress in exhaled breath, exhaled breath condensate, and urine are among them. It is also important to consider the occupational health and safety risks associated with the use of various new materials in 3D printing, which are associated with skin irritation and sensitivity risks. Therefore, EDI (estimated daily intake) calculations for assessment of the potential occupational health risk purposes via inhalation and dermal exposure are critical in future. The assessment of occupational exposure and health risks of 3D printing processes is essential for the proper identification, control, and prevention of working conditions, also for the diagnosis and monitoring of occupational diseases among workers to improve public health and well-being in general

HA-TiO2/ZrO2 kompozītā keramika

HA keramiku veido ar dažādu struktūru - poru izmēriem un blīvumu. Funkcionāli graduētai porainai keramikai ir vairākas priekšrocības, piemēram, graduētās poras rada vienmērīgu slodzes pārnesi un līdz minimumam samazina sprieguma vairoga problēmu un veicina osteosaistīšanos