Indoor aerosols: from personal exposure to risk assessment[edit | edit source]
Morawska, L. , Afshari, A. , Bae, G. N., Buonanno, G. , Chao, C. Y., Hänninen, O. , Hofmann, W. , Isaxon, C. , Jayaratne, E. R., Pasanen, P. , Salthammer, T. , Waring, M. and Wierzbicka, A. (2013), Indoor aerosols: from personal exposure to risk assessment. Indoor Air, 23: 462-487.
Abstract
Motivated by growing considerations of the scale, severity, and risks associated with human exposure to indoor particulate matter, this work reviewed existing literature to: (i) identify state‐of‐the‐art experimental techniques used for personal exposure assessment; (ii) compare exposure levels reported for domestic/school settings in different countries (excluding exposure to environmental tobacco smoke and particulate matter from biomass cooking in developing countries); (iii) assess the contribution of outdoor background vs indoor sources to personal exposure; and (iv) examine scientific understanding of the risks posed by personal exposure to indoor aerosols. Limited studies assessing integrated daily residential exposure to just one particle size fraction, ultrafine particles, show that the contribution of indoor sources ranged from 19% to 76%. This indicates a strong dependence on resident activities, source events and site specificity, and highlights the importance of indoor sources for total personal exposure. Further, it was assessed that 10–30% of the total burden of disease from particulate matter exposure was due to indoor‐generated particles, signifying that indoor environments are likely to be a dominant environmental factor affecting human health. However, due to challenges associated with conducting epidemiological assessments, the role of indoor‐generated particles has not been fully acknowledged, and improved exposure/risk assessment methods are still needed, together with a serious focus on exposure control.
Own Comments:
- State of the art indoor aerosols personal exposure
EXPERIMENTAL STUDY OF MECHANICAL PROPERTIES OF ADDITIVELY MANUFACTURED ABS PLASTIC AS A FUNCTION OF LAYER PARAMETERS[edit | edit source]
Todd Letcher, Behzad Rankouhi, Sina Javadpour, "EXPERIMENTAL STUDY OF MECHANICAL PROPERTIES OF ADDITIVELY MANUFACTURED ABS PLASTIC AS A FUNCTION OF LAYER PARAMETERS", ASME 2015 International Mechanical Engineering Congress and Exposition, Volume 2A: Advanced Manufacturing, November 13–19, 2015. [2]
Abstract In this study, a preliminary effort was undertaken to represent the mechanical properties of a 3D printed specimen as a function of layer number, thickness and raster orientation by investigating the correlation between the mechanical properties of parts manufactured out of ABS using Fused Filament Fabrication (FFF) with a commercially available 3D printer, Makerbot Replicator 2x, and the printing parameters, such as layer thickness and raster orientation, were considered. Specimen were printed at raster orientation angles of 0°, 45° and 90°. Layer thickness of 0.2 mm was chosen to print specimens from a single layer to 35 layers. Samples were tested using an MTS Universal Testing Machine with extensometer to determine mechanical strength characteristics such as modulus of elasticity, ultimate tensile strength, maximum force and maximum elongation as the number of layers increased. Results showed that 0° raster orientation yields the highest mechanical properties compared to 45° and 90° at each individual layer. A linear relationship was found between the number of layers and the maximum force for all three orientations, in other words, maximum force required to break specimens linearly increased as the number of layers increased. The results also found the elastic modulus and maximum stress to increase as the number of layers increased up to almost 12 layers. For samples with more than 12 layers, the elastic modulus and maximum stress still increased, but at a much slower rate. These results can help software developers, mechanical designers and engineers reduce manufacturing time, material usage and cost by eliminating unnecessary layers that do not increase the ultimate stress of the material by improving material properties due to the addition of layers.
Own Comments:
- O deg. raster orientation yields highest strength
- ASTM D638 was used however stress concenteration at fillet areas led to premature failure
- Rectangular version of ASTM D638 was used instead
Field Evaluation of Personal Sampling Methods for Multiple Bioaerosols[edit | edit source]
Wang CH, Chen BT, Han BC, Liu ACY, Hung PC, et al. (2015) Field Evaluation of Personal Sampling Methods for Multiple Bioaerosols. PLOS ONE 10(3): e0120308. [3]
Ambient bioaerosols are ubiquitous in the daily environment and can affect health in various ways. However, few studies have been conducted to comprehensively evaluate personal bioaerosol exposure in occupational and indoor environments because of the complex composition of bioaerosols and the lack of standardized sampling/analysis methods. We conducted a study to determine the most efficient collection/analysis method for the personal exposure assessment of multiple bioaerosols. The sampling efficiencies of three filters and four samplers were compared. According to our results, polycarbonate (PC) filters had the highest relative efficiency, particularly for bacteria. Side-by-side sampling was conducted to evaluate the three filter samplers (with PC filters) and the NIOSH Personal Bioaerosol Cyclone Sampler. According to the results, the Button Aerosol Sampler and the IOM Inhalable Dust Sampler had the highest relative efficiencies for fungi and bacteria, followed by the NIOSH sampler. Personal sampling was performed in a pig farm to assess occupational bioaerosol exposure and to evaluate the sampling/analysis methods. The Button and IOM samplers yielded a similar performance for personal bioaerosol sampling at the pig farm. However, the Button sampler is more likely to be clogged at high airborne dust concentrations because of its higher flow rate (4 L/min). Therefore, the IOM sampler is a more appropriate choice for performing personal sampling in environments with high dust levels. In summary, the Button and IOM samplers with PC filters are efficient sampling/analysis methods for the personal exposure assessment of multiple bioaerosols.
Own Comments:
- Field tested several personal sampler, would be interesting to know what kind of attachment they used
Personal exposure monitoring of PM2.5 in indoor and outdoor microenvironments[edit | edit source]
Steinle, S., Reis, S., Sabel, C.E., Semple, S., Twigg, M.M., Braban, C.F., Leeson, S.R., Heal, M.R., Harrison, D., Lin, C., Wu, H., 2015. Personal exposure monitoring of PM2.5 in indoor and outdoor microenvironments. Science of The Total Environment 508, 383–394. https://doi.org/10.1016/j.scitotenv.2014.12.003
Abstract
Adverse health effects from exposure to air pollution are a global challenge and of widespread concern. Recent high ambient concentration episodes of air pollutants in European cities highlighted the dynamic nature of human exposure and the gaps in data and knowledge about exposure patterns. In order to support health impact assessment it is essential to develop a better understanding of individual exposure pathways in people's everyday lives by taking account of all environments in which people spend time. Here we describe the development, validation and results of an exposure method applied in a study conducted in Scotland.
A low-cost particle counter based on light-scattering technology — the Dylos 1700 was used. Its performance was validated in comparison with equivalent instruments (TEOM-FDMS) at two national monitoring network sites (R2 = 0.9 at a rural background site, R2 = 0.7 at an urban background site). This validation also provided two functions to convert measured PNCs into calculated particle mass concentrations for direct comparison of concentrations with equivalent monitoring instruments and air quality limit values.
This study also used contextual and time-based activity data to define six microenvironments (MEs) to assess everyday exposure of individuals to short-term PM2.5 concentrations. The Dylos was combined with a GPS receiver to track movement and exposure of individuals across the MEs. Seventeen volunteers collected 35 profiles. Profiles may have a different overall duration and structure with respect to times spent in different MEs and activities undertaken. Results indicate that due to the substantial variability across and between MEs, it is essential to measure near-complete exposure pathways to allow for a comprehensive assessment of the exposure risk a person encounters on a daily basis. Taking into account the information gained through personal exposure measurements, this work demonstrates the added value of data generated by the application of low-cost monitors.
Own Comments:
- Instruments attached to worker in a backpack
Failure Analysis and Mechanical Characterization of 3D Printed ABS With Respect to Layer Thickness and Orientation[edit | edit source]
Behzad Rankouhi, Sina Javadpour, Fereidoon Delfanian, Todd Letcher, "Failure Analysis and Mechanical Characterization of 3D Printed ABS With Respect to Layer Thickness and Orientation",Journal of Failure Analysis and Prevention, Vol(16), Issue 3, 467-481, 2016. [5]
Abstract In contrast to conventional subtractive manufacturing methods which involve removing material to reach the desired shape, additive manufacturing is the technology of making objects directly from a computer-aided design model by adding a layer of material at a time. In this study, a comprehensive effort was undertaken to represent the strength of a 3D printed object as a function of layer thickness by investigating the correlation between the mechanical properties of parts manufactured out of acrylonitrile butadiene styrene (ABS) using fused deposition modeling and layer thickness and orientation. Furthermore, a case study on a typical support frame is done to generalize the findings of the extensive experimental work done on tensile samples. Finally, fractography was performed on tensile samples via a scanning digital microscope to determine the effects of layer thickness on failure modes. Statistical analyses proved that layer thickness and raster orientation have significant effect on the mechanical properties. Tensile test results showed that samples printed with 0.2 mm layer thickness exhibit higher elastic modulus and ultimate strength compared with 0.4 mm layer thickness. These results have direct influence on decision making and future use of 3D printing and functional load bearing parts.
Own Comments:
- No specific standard tests avaliable for parts using FDM
- ASTM D638 best choice however stress concenteration at fillet areas
- ASTM D3039 guidelines were used to prepare the samples
- 0.2 mm thickness specimen are stronger than 0.4 mm
- Smaller air gap material ratio can be main factor towards higher strength
- layer thickness and raster orientation have significant effect on material properties
Bioaerosol sampling: sampling mechanisms, bioefficiency and field studies[edit | edit source]
Haig, C.W., Mackay, W.G., Walker, J.T., Williams, C., 2016. Bioaerosol sampling: sampling mechanisms, bioefficiency and field studies. Journal of Hospital Infection 93, 242–255.
https://doi.org/10.1016/j.jhin.2016.03.017
Summary
Investigations into the suspected airborne transmission of pathogens in healthcare environments have posed a challenge to researchers for more than a century. With each pathogen demonstrating a unique response to environmental conditions and the mechanical stresses it experiences, the choice of sampling device is not obvious. Our aim was to review bioaerosol sampling, sampling equipment, and methodology. A comprehensive literature search was performed, using electronic databases to retrieve English language papers on bioaerosol sampling. The review describes the mechanisms of popular bioaerosol sampling devices such as impingers, cyclones, impactors, and filters, explaining both their strengths and weaknesses, and the consequences for microbial bioefficiency. Numerous successful studies are described that point to best practice in bioaerosol sampling, from the use of small personal samplers to monitor workers' pathogen exposure through to large static samplers collecting airborne microbes in various healthcare settings. Of primary importance is the requirement that studies should commence by determining the bioefficiency of the chosen sampler and the pathogen under investigation within laboratory conditions. From such foundations, sampling for bioaerosol material in the complexity of the field holds greater certainty of successful capture of low-concentration airborne pathogens. From the laboratory to use in the field, this review enables the investigator to make informed decisions about the choice of bioaerosol sampler and its application.
Review of measurement techniques and methods for assessing personal exposure to airborne nanomaterials in workplace[edit | edit source]
Asbach, C., Alexander, C., Clavaguera, S., Dahmann, D., Dozol, H., Faure, B., Fierz, M., Fontana, L., Iavicoli, I., Kaminski, H., MacCalman, L., Meyer-Plath, A., Simonow, B., van Tongeren, M., Todea, A.M., 2017. Review of measurement techniques and methods for assessing personal exposure to airborne nanomaterials in workplaces. Science of The Total Environment 603–604, 793–806. https://doi.org/10.1016/j.scitotenv.2017.03.049
Highlights
- Personal samplers and monitors are robust and ready for field-use.
- Typical accuracy of personal samplers and monitors around ± 30%
- Combination of personal sampler and monitor may be the optimal choice.
- Clear measurement strategy needed for assessing personal exposure
Abstract
Exposure to airborne agents needs to be assessed in the personal breathing zone by the use of personal measurement equipment. Specific measurement devices for assessing personal exposure to airborne nanomaterials have only become available in the recent years. They can be differentiated into direct-reading personal monitors and personal samplers that collect the airborne nanomaterials for subsequent analyses. This article presents a review of the available personal monitors and samplers and summarizes the available literature regarding their accuracy, comparability and field applicability. Due to the novelty of the instruments, the number of published studies is still relatively low. Where applicable, literature data is therefore complemented with published and unpublished results from the recently finished nanoIndEx project. The presented data show that the samplers and monitors are robust and ready for field use with sufficient accuracy and comparability. However, several limitations apply, e.g. regarding the particle size range of the personal monitors and their in general lower accuracy and comparability compared with their stationary counterparts.
The decision whether a personal monitor or a personal sampler shall be preferred depends strongly on the question to tackle. In many cases, a combination of a personal monitor and a personal sampler may be the best choice to obtain conclusive results.
Mechanical properties of components fabricated with open-source 3-D printers under realistic environmental conditions[edit | edit source]
B.M. Tymrak a, M. Kreiger b, J.M. Pearce, "Mechanical properties of components fabricated with open-source 3-D printers under realistic environmental conditions", Materials and Design, Vol(58), 242-246, 2014. [8]
Abstract The recent development of the RepRap, an open-source self-replicating rapid prototyper, has made 3-D polymer-based printers readily available to the public at low costs ( < $500). The resultant uptake of 3-D printing technology enables for the first time mass-scale distributed digital manufacturing. RepRap variants currently fabricate objects primarily from acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA), which have melting temperatures low enough to use in melt extrusion outside of a dedicated facility, while high enough for prints to retain their shape at average use temperatures. In order for RepRap printed parts to be useful for engineering applications the mechanical properties of printed parts must be known. This study quantifies the basic tensile strength and elastic modulus of printed components using realistic environmental conditions for standard users of a selection of open-source 3-D printers. The results find average tensile strengths of 28.5 MPa for ABS and 56.6 MPa for PLA with average elastic moduli of 1807 MPa for ABS and 3368 MPa for PLA. It is clear from these results that parts printed from tuned, low-cost, open-source RepRap 3-D printers can be considered as mechanically functional in tensile applications as those from commercial vendors.
Own Comments:
- Mechanical properties of OS RepRap 3D printers
- AVG. UTS ABS: 28.5 MPa (Improvised ASTM: D638 with realistic environmental conditions of distrb. Manuf.)
- AVG. Modulus ABS: 1807 MPa (Improvised ASTM: D638 with realistic environmental conditions distrb. Manuf.)
- AVG. UTS PLA: 56.6 MPa (Improvised ASTM: D638 with realistic environmental conditions distrb. Manuf.)
- AVG. Modulus PLA: 3368 MPa (Improvised ASTM: D638 with realistic environmental conditions distrb. Manuf.)
- ABS Orientation x-y plane 0/90: highest E
- ABS Orientationx-y plane +45/-45: strongest TS
- ABS Layer thickness of 0.2mm: greatest TS
- ABS Layer thickness of 0.4mm: greatest E
Chemical Compatibility of Fused Filament Fabrication -based 3-D Printed Components with Solutions Commonly Used in Semiconductor Wet Processing[edit | edit source]
Ismo T. S. Heikkinen, Christoffer Kauppinen, Zhengjun Liu, Sanja M. Asikainen, Steven Spoljaric, Jukka V. Seppälä, Hele Savin, and Joshua M. Pearce*, "Chemical Compatibility of Fused Filament Fabrication-based 3-D Printed Components with Solutions Commonly Used in Semiconductor Wet Processing", Submitted, 2018. [9]*
Own Comments:
- AM polymer(10 types) parts: can be compatible for operation under concentrated chemical conditions.
- Cost reductions of over 90% with chemically resistant labware.
- ABS compatible with 7/11 (moderate to good) types of different chemical solutions (T:1 week).
- PP compatible with 11/11 (moderate to good) types of different chemical solutions (T:1 week).
Patents[edit | edit source]
personal dust sampler holder[edit | edit source]
Spring action retainers hold a particle separation cyclone and an air filter in operative position for filtering air samples drawn through an inlet aperture in the cyclone. The retainers include a fuse-type spring clip and a flat apertured retaining plate joined to the clip by coil springs. The filter and cyclone are supported by the clip at the neck of the cyclone adjacent the inlet aperture. The retaining plate, positioned over the filter, biases the cyclone and filter combination against a flange on the lower portion of the clip. A tubular connector, secured through the aperture in the retaining plate, connects with the filter on one side, and with a vacuum hose on the other side for connecting the filter outlet to the inlet of an air metering pump. The clip and several hose guides are scoured to a supporting plate which includes a pin-type fastener for attaching the sampler holder to the garment of a person in his breathing zone when collecting respirable dust samples
Expired (1969)
Own comments:
- Sampler attached to the clothing with safety pin
Disposable air sampling filter cassette[edit | edit source]
Expired (1970)
A composite filter unit and cassette to serve as an air sampler for personal use in connection with a metering pump and a cyclone unit. The filter unit is formed of two opposed shells with interfitting flanges to provide a support for the circumferential edges of a filter disc and to form chambers on each side of the disc, one to serve as an inlet and one to serve as an outlet. The chambers are provided with tangential openings so that inlet air is directed parallel to the disc in a toroidal path where it can flow uniformly through the filter disc to the opposed chamber and outlet. The composite filter unit is encapsulated in a cassette during use to protect it against outside contamination, the encapsulator having a special configuration for cooperation with a garment support bracket.
Own comments:
- Old design, where you can see how it was attached before
Personal sampling pump[edit | edit source]
Expired (1980)
"Personal sampling pumps are small battery operated vacuum pumps intended to be worn on the person to monitor the exposure of the wearer to hazardous atmospheric conditions."
Cyclone personal sampler for aerosols[edit | edit source]
Expired (1989)
"The present invention relates to a personal sampler, that is one which is of sufficiently small size so that it can be worn by a user to determine the quality of air being respirated, which utilizes a two-stage cyclone evaluator that includes a conventional elongated personal cyclone separator that has a lower cut-off size of in the range of 10 microns."
Universal backpack harness[edit | edit source]
Expired (1996)
Own comments:
- Harness design
Personal particle monitor[edit | edit source]
Active (2001)
Provided is a personal sampler for PM that allows separation of airborne particles in several size ranges and operates at a high flow rate (9 L/min) by personal sampling standards that makes chemical analysis of the size-fractionated particles possible within a period of 24 hours or less
Own comments:
- This could totally use univeral clip-on design
Harness for firearm accessories[edit | edit source]
Active (2006)
Own comments:
- Harness design
- also includes gun attached to the harness with a clip-on
Compact aerosol sampler[edit | edit source]
Active (2009)
Provided is an aerosol collector of reduced size having an aerosol inlet, an impactor plate containing several particle size-selecting nozzles therethrough, a replaceable collection layer and a fan having a power supply such as a battery pack, all of which fits a small container, attachable to, e.g., the lapel of the user, means to rotate the fan and move the aerosol through the sampler, so as to draw airborne particles through the inlet and through one or more nozzles, to impact the particles on the layer for analysis of same.
Own comments:
- Attachment to the clothing
Personal nanoparticle respiratory depositions sampler and methods of using the same[edit | edit source]
Active (2012)
A personally portable nanoparticle respiratory deposition (NRD) sampler configured to collect nanoparticles based upon a sampling criterion. In an aspect, the NRD sampler has an impactor stage, and a diffusion stage. In another aspect, the NRD sampler includes a particle size separator in addition to an impactor stage and a diffusion stage.
Guidelines and Data Sheets[edit | edit source]
Standard Test Method for Tensile Properties of Plastics[edit | edit source]
ASTM D638-14, Standard Test Method for Tensile Properties of Plastics, ASTM International, West Conshohocken, PA, 2014 [19]
This test method is designed to produce tensile property data for the control and specification of plastic materials. These data are also useful for qualitative characterization and for research and development.
Standard Guide for Air Sampling Strategies for Worker and Workplace Protection[edit | edit source]
ASTM E1370-14, Standard Guide for Air Sampling Strategies for Worker and Workplace Protection, ASTM International, West Conshohocken, PA, 2014, www.astm.org
DOI: 10.1520/E1370
Standard Test Method for Respirable Dust in Workplace Atmospheres Using Cyclone Samplers[edit | edit source]
ASTM D4532-15, Standard Test Method for Respirable Dust in Workplace Atmospheres Using Cyclone Samplers, ASTM International, West Conshohocken, PA, 2015, www.astm.org DOI: 10.1520/D4532-15
ISO/ASTM 52900:2015[edit | edit source]
Additive manufacturing -- General principles -- Terminology
ISO/ASTM 52900:2015 establishes and defines terms used in additive manufacturing (AM) technology, which applies the additive shaping principle and thereby builds physical 3D geometries by successive addition of material. The terms have been classified into specific fields of application.
Own Comments
- ISO/ASTM approved AM methods and definitions
Safety Data Sheet[edit | edit source]
Stratasys Direct, Inc., "Safety Data Sheet", 2015.
Accessed 30.04.2018
Safety Data Sheet for ABS-M30/P430 ABS/P430XL ABS/ABSplus Model Material
Own Comments:
- Not dangerous according to (REGULATION (EC) No 1272/2008)
- Eye contact: rinse
- Extinguishing Media: water, dry powder, foam, CO2
- Keep tightly closed in a dry and cool place.
- Does not contain any hazardous materials with occupational exposure limits established by the region specific regulatory bodies.
- Contains no substances known to be hazardous to the environment or that are not degradable in waste water treatment plants.
- Handle in accordance with good industrial hygiene and safety practice.
- No protective equipment is needed under normal use conditions.
Fused Deposition Modeling (FDM) Design Guidelines[edit | edit source]
Stratasys Direct, Inc., "Fused Deposition Modeling (FDM) Design Guidelines", 2015.
Accessed 30.04.2018
Part Design For FDM
These guidelines are to be used as a starting point in understanding the basic aspects of part design and preparation for FDM components. When designing a part to be built using FDM technology, build process must be considered. FDM is accomplished by extruding thin layers of molten thermoplastic layer by layer until a part is produced. Because FDM produces parts with specific characteristics and capabilities different from those of other prototyping processes, the systems have become increasingly used as a tool for producing manufactured products.
Own Comments:
- FDM Design considerations according to uPrint SE Pro
ISO / ASTM52910-17, Standard Guidelines for Design for Additive Manufacturing[edit | edit source]
ISO / ASTM52910-17, Standard Guidelines for Design for Additive Manufacturing , ASTM International, West Conshohocken, PA, 2016, www.astm.org
DOI: 10.1520/ISOASTM52910-17
ABSplus-P430: Production-Grade Thermoplastic for 3D Printers[edit | edit source]
Stratasys Direct, Inc., "ABSplus-P430: Production-Grade Thermoplastic for 3D Printers", 2017.
Accessed 30.04.2018
Mechanical properties of ABS plus (natural)
Own Comments:
- UTS:33MPa (ASTM D638)
- YTS: 31MPa (ASTM D638)
- Tensile Modulus: 2200 MPa (ASTM D638)
- Toughness: 106 J/m (ASTM D638)
- Hardness: 109.5 (ASTM D785)
- Thermal Properties of ABS plus (ASTM D648)
- Electrical Properties of ABS plus (ASTM D257, D150-98 and D149-09)
Standard Test Method for Tensile Properties of Polymer Matrix Composite Materials[edit | edit source]
ASTM D3039 / D3039M-17, Standard Test Method for Tensile Properties of Polymer Matrix Composite Materials, ASTM International, West Conshohocken, PA, 2017 [27]
This test method is designed to produce tensile property data for material specifications, research and development, quality assurance, and structural design and analysis. Factors that influence the tensile response and should therefore be reported include the following: material, methods of material preparation and lay-up, specimen stacking sequence, specimen preparation, specimen conditioning, environment of testing, specimen alignment and gripping, speed of testing, time at temperature, void content, and volume percent reinforcement.
Personal Sampling for Air Contaminants[edit | edit source]
OSHA GUIDELINES
Software[edit | edit source]
FreeCad[edit | edit source]
Original Authors: Jürgen Riegel, Werner Mayer, Yorik van Havre, "FreeCad", 2018 [29]
FreeCAD is a parametric 3D modeler made primarily to design real-life objects of any size. Parametric modeling allows you to easily modify your design by going back into your model history and changing its parameters. FreeCAD is open-source and highly customizable, scriptable and extensible.
Own Comments:
- Used for modeling
- The bug fix release 0.17.13519 was published 2018-04-23
Netfabb[edit | edit source]
Autodesk Inc., "Netfabb", 2018 [30]
Netfabb brings additive design and manufacturing tools together in a single software environment, giving product designers and engineers all the tools they need to optimize, validate and successfully produce models using additive manufacturing processes.
Own Comments:
- Used for STL repair
- Free for Students and Educators
