Actual Exposure Conditions Research Articles

Nicotinamide Alleviates Synergistic Impairment of Intestinal Barrier Caused by MC-LR and NaNO2 Coexposure.

Microcystin-LR (MC-LR) and nitrites from the environment and daily life can be ingested and absorbed by humans via the digestive tract. However, their combined effects on intestinal health remain unclear. Here, the combined impact of MC-LR and sodium nitrite (NaNO2) on the intestines of mice was investigated under actual human exposure conditions. After mice were exposed to MC-LR (10, 100 μg/L) and NaNO2 (30, 300 mg/L) individual and in combination for 6 months, it was found that MC-LR and NaNO2 synergistically decreased intestinal permeability and disrupted intestinal physical, chemical, immune, and microbial barriers. In the coexposure groups, the synergistic impairment to the intestinal barrier was noted with increasing concentrations of MC-LR or NaNO2, but this adverse effect was alleviated by nicotinamide supplementation. This study underscores the potential risks of simultaneous ingestion of MC-LR and nitrite on intestinal health. The protective role of nicotinamide suggests avenues for therapeutic intervention against environmental toxin-induced intestinal impairment.

A new approach for risk assessment of pulmonary toxicants: a preliminary study using didecyldimethylammonium chloride.

Current human risk assessments often rely on animal toxicity data to establish point of departure (POD) values, followed by the application of uncertainty factors. Consequently, there is growing interest in alternative toxicity testing methods that reduce reliance on animal models. In this study, we propose a novel approach for inhalation toxicity risk assessment that integrates in silico and in vitro methods. Human primary alveolar epithelial cells were exposed to aerosolized didecyldimethylammonium chloride (DDAC) to assess cytotoxicity. This was followed by transcriptome analysis and biological pathway investigation, utilizing adverse outcome pathway (AOP), to calculate the POD. Additionally, human DDAC exposure was simulated using a multiple-path particle dosimetry (MPPD) model to predict exposure levels in the human alveolar region via inhalation. The results from in silico and in vitro studies were then compared, and a comprehensive risk assessment was performed. The POD for AOP 452 key events-oxidative stress, inflammation, epithelial-mesenchymal transition (EMT), apoptosis, and autophagy-was found to range between 19.0 and 23.89ng/cm2, according to benchmark dose calculation tools. The estimated human exposure to DDAC in the alveolar region under actual exposure conditions was 0.164ng/cm2/day, resulting in a margin of exposure (MOE) ranging from 121 to 145, suggesting caution regarding DDAC inhalation exposure. This study presents a novel risk assessment method that compares estimated human inhalation exposure values to in vitro results, applying the human equivalent concentration concept. Our findings demonstrate the potential for conducting human risk assessments using both in silico and in vitro methods as alternatives to traditional in vivo studies.

Conservative assessment of external radiation dose for staff in the event of radionuclide flaw detection

The article proposes a new approach to assessing the effective doses of flaw detectorists performing flaw detection using portable radionuclide flaw detectors (gamma flaw detectors). The existing approach to assessing effective doses, based on the use of one individual dosimeter placed on work clothes in the chest area, is inadequate for the actual working conditions of exposure of flaw detectorists. Gamma flaw detectors contain a closed man-made source of ionizing radiation in their head, therefore, even in the non-working position, such flaw detectors pose a radiation hazard. When transporting and preparing gamma flaw detectors for work, the flaw detector operator is in close proximity to the radiation source. The irradiation geometry changing during the technological cycle when working with portable gamma flaw detectors at certain stages creates a sharply uneven irradiation of the flaw detectorist’s body. Therefore, after assessing the stages of the technological cycle, an option was proposed for a more conservative assessment of effective doses – to change the location of the individual dosimeter on the working clothes of the flaw detectorist, moving the individual dosimeter to the abdominal area. An anonymous study was carried out with the participation of 15 flaw detectorists; three individual dosimeters were displayed on their working clothes: two of them were experimental and were placed in the chest and abdomen; the third (a control dosimeter) was exposed for the quarter on the chest as part of constant individual dosimetric monitoring. In controlled anonymous measurements, the average effective dose, estimated from the readings of dosimeters exposed in the chest area, was equal to 0,95 mSv (median – 0,92 mSv, maximum value – 1,27 mSv). These values were compared with values obtained using dosimeters that were exposed to the abdomen, and the differences were significant (the average effective dose was 1,24 mSv (median – 1,22 mSv, maximum value – 1,78 mSv).

Duration and resource constraint prediction models for construction projects using regression machine learning method

PurposeThe construction projects are highly subjected to uncertainties, which result in overruns in time and cost. Realistic estimates of workforce and duration are imperative for construction projects to attain their intended objectives. The aim of this study is to provide accurate labor and duration estimates for the construction projects, considering actual uncertainties.Design/methodology/approachThe dataset was formulated from the information collected from 186 construction projects through direct interviews, group discussions and questionnaire methods. The actual uncertainties and exposure conditions of construction activities were recorded. The data were verified with the standard guideline to remove the outliers. The prediction model was developed using support vector regression (SVR), a machine learning (ML) method. The performance was evaluated using the widely adopted regression metrics. Further, the cross validation was made with the visualization of residuals and predicted errors, ridge regression with transformed target distribution and a Gaussian Naive Bayes (NB) regressor.FindingsThe prediction models predicted the duration and labor requirements with the consideration of actual uncertainties. The residual plot indicated the appropriate use of SVR to develop the prediction model. The duration (DC) and resource constraint (RC) prediction models obtained 80 and 82% accuracy, respectively. Besides, the developed model obtained better accuracy for the training and test scores than the Gaussian NB regressor. Further, the range of the explained variance score and R2 was from 0.95 to 0.97, indicating better efficiency compared with other prediction models.Research limitations/implicationsThe researchers will utilize the research findings to estimate the duration and labor requirements under uncertain conditions and further improve the construction project management practices.Practical implicationsThe research findings will enable industry practitioners to accurately estimate the duration and labor requirements, considering historical uncertain conditions. A precise estimation of resources will ensure the attainment of the intended project outcomes.Social implicationsDelays in construction projects will be reduced by implementing the research findings, which significantly ensures the effective utilization of resources and attainment of other economic benefits. The policymakers will develop a guideline to develop a database to collect the uncertainties of the construction projects and relatively estimate the resource requirements.Originality/valueThis is the first study to consider the actual uncertainties of construction projects to develop RC and DC prediction models. The developed prediction models accurately estimate the duration and labor requirements with minimal computational time. The industry practitioners will be able to accurately estimate the duration and labor requirements using the developed models.

Refinement of the acute inhalation limit test for inert, nano-sized dusts by an in silico dosimetry-based evaluation: case study for the dissolution of a regulatory dilemma.

This case study aims to describe the dilemma faced when exposing rats to very high concentrations of fine, pulverulent materials for acute inhalation studies and to address the regulatory question of whether the effects seen here are relevant to humans and the subject of classification according to the Globally Harmonized System of Classification and Labeling of Chemicals (GHS). Many powders match the definition of nanomaterials in the EU; therefore, information on acute inhalation testing of powders up to the GHS cutoff of 5mg/L is required. However, testing rats at such a high aerosol concentration can cause physical obstruction of the airways and even mortality by suffocation. Therefore, to evaluate whether the physical effects on airway obstruction in rats exposed to 5mg/L for 4hours and alternative exposures to 1 and 2mg/L are relevant for humans, an in silico evaluation of aerosol deposition was conducted using the multiple-path particle dosimetry (MPPD) model. For this evaluation, actual exposure conditions for an organic, nano-sized pigment which produced 100% lethality in rats at 5mg/L, but not at 1mg/L, were used to assess the potential for airway obstruction in rats and accordingly in humans. As an indicator of the potential for airway obstruction, the ratio of the diameter of the deposited, aggregated aerosol to airway diameter was calculated for each exposure condition. For rats exposed to 5mg/L for 4h, approximately 75% of tracheobronchial and 22% of pulmonary/alveolar airways were considered vulnerable to significant or complete obstruction (ratios >0.5). In humans, an equivalent exposure resulted in just over 96% of human tracheobronchial airways that received deposited mass to airway diameter ratios between 0.3 and 0.4 (nasal) or 0.4 and 0.5 (oral), with no airways with ratios >0.5. For the pulmonary/alveolar region, ∼88% of the airways following nasal or oral breathing were predicted to have deposited aerosol diameter to airway diameter ratios <0.1, with no airways with ratios >0.5. Thus, the in silico results obtained for rats are in line with the pathological findings of the animal test. The predicted results in humans, however, affirm the hypothesis of a rat-specific high dose effect which does not justify a classification according to GHS.

To avoid overestimation of microplastics released from actual usage of disposable cups: In-depth quantitative analysis of microplastics and simultaneously exposed chemicals

The use of disposable plastic cups has increased because they are sanitary and easy to use. Microplastics (MPs) from plastic products occur extensively in the environment and threaten human health. Measuring and quantifying MP release under various exposure conditions using micro-Fourier-transform infrared spectroscopy is controversial. This study simulated MP release under actual usage exposure conditions. The cups were exposed to 100 mL of liquid simulants (deionized water and coffee) at 20, 60, and 100 °C for 0.5, 1.0, 2.0, and 3.0 h. Contrary to previous studies, lower amounts of polythene-MPs (1–40 particles/100 mL) were released at 100 °C and comparable amounts in the coffee simulants; unexpectedly, glycol monooleate migrated in 10-fold higher amounts. The MP release mechanism was examined based on surface roughness and contact angle changes, which support polyethylene film fragmentation. The most important factor for MPs release was exposure time, while temperature of the liquid simulant was the critical factor for plasticizer (GMO) migration. PE-MP release and migration of the plasticizer (glycerol monooleate) smoothed the rough surface, making the hydrophobic surface more hydrophilic.

Comparison between Communicated and Calculated Exposure Estimates Obtained through Three Modeling Tools.

This study aims to evaluate the risk assessment approach of the REACH legislation in industrial chemical departments with a focus on the use of three models to calculate exposures, and discuss those factors that can determine a bias between the estimated exposure (and therefore the expected risk) in the extended safety data sheets (e-SDS) and the expected exposure for the actual scenario. To purse this goal, the exposure estimates and risk characterization ratios (RCRs) of registered exposure scenarios (ES; “communicated exposure” and “communicated RCR”) were compared with the exposure estimates and the corresponding RCRs calculated for the actual, observed ES, using recommended tools for the evaluation of exposure assessment and in particular the following tools: (i) the European Centre for Ecotoxicology and Toxicology of Chemicals Targeted Risk Assessment v.3.1 (ECETOC TRA), (ii) STOFFENMANAGER® v.8.0 and (iii) the Advanced REACH Tool (ART). We evaluated 49 scenarios in three companies handling chemicals. Risk characterization ratios (RCRs) were calculated by dividing estimated exposures by derived no-effect levels (DNELs). Although the calculated exposure and RCRs generally were lower than communicated, the correlation between communicated and calculated exposures and RCRs was generally poor, indicating that the generic registered scenarios do not reflect actual working, exposure and risk conditions. Further, some observed scenarios resulted in calculated exposure values and RCR higher than those communicated through chemicals’ e-SDSs; thus ‘false safe’ scenarios (calculated RCRs > 1) were also observed. Overall, the obtained evidences contribute to doubt about whether the risk assessment should be performed using generic (communicated by suppliers) ES with insufficient detail of the specific scenario at all companies. Contrariwise, evidences suggested that it would be safer for downstream users to perform scenario-specific evaluations, by means of proper scaling approach, to achieve more representative estimates of chemical risk.

Material qualification of a 13Cr-L80 casing for sour conditions

Abstract This work aims to determine the material qualification of 13Cr-L80 casing for sour conditions which is of great importance to check the sulfide stress cracking susceptibility, confirm the range of applicable conditions and recommend anti-corrosion materials. First, the casing material was tested to judge whether its properties were normal. Secondly, the testing matrix was defined to determine actual casing exposure conditions. Thirdly, slow strain rate testing was used to screen the conditions. Fourthly, thirty-day tests of uniaxial tensile specimens were conducted to check for SSC susceptibility. The casing material satisfied API 5CT standards and could be used for slow strain rate testing and sulfide stress cracking testing. The testing matrix is intended to distinguish the combined effect of temperatures (41, 75, 140 °F), chloride levels (1000, 13 000 mg × L−1), pH (3.5, 5.5) and partial pressures of H2S (3.5 psi) in shut-in and flowing conditions. The slow strain rate testing showed a reduction of signs of embrittlement with increased temperature, suggesting that the mechanism is supported by sulfide stress cracking. The 13Cr-L80 passed field-specific qualification tests for sulfide stress cracking resistance in sour wells at maximum H2S partial pressures of 3.5 psi in the casing-tubing annulus. The API 5CT 13Cr-L80 casing application is in compliance with ISO15156/NACE MR0175 standards as long as the aggressiveness of the field conditions does not go beyond the envelope conditions tested (3.5 psi of H2S, pH 3.5, temperature of 41 or 75 °F).

A survey of sources of incoherent artificial optical radiation in a hospital environment in accordance with European Directive 2006/25/EC: evaluation of the related exposure risk

The evaluation of incoherent artificial optical radiation (AOR) exposure in hospital environments is a complex task due to the variety of sources available. This study has been designed to provide a proposal for the precautionary assessment of the related risk.This survey suggested that, in our Institution, at least three kinds of AOR sources required specific investigations: ambient lighting, theatre operating lighting and ultraviolet radiation (UVR) sources. For each kind of evaluated sources a specific measurement approach was developed. All irradiance measurements were made using a commercial spectroradiometer. The obtained results were compared with the appropriate exposure limit values (ELVs) defined in the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines and adopted by the European Directive 2006/25/EC. The risk related to the evaluated AOR exposure was finally assessed according to our risk matrix.According to our results, the emission of ambient lighting in the actual exposure conditions was always in accordance with the ELVs and the related risk was classifiable as not relevant. The risk related to the exposure to theatre operating lighting resulted not negligible, especially when two or more sources were used with focal spots overlapping on reflective objects. UVR sources emission may represent a health hazard depending, in particular, on the set up of the device containing the source. In case of laminar flow cabinets and closed transilluminators, if the UVR source is well contained within an enclosure with interlock, it presents no risk of exposure. Otherwise, the emission arising from UVR lamps, open transilluminators or sources not provided with interlock, may represent a risk classifiable as high even in the actual working conditions. The personal protective equipment used by workers were also assessed and their suitability was discussed.

Influence of anti-smoking education and smoke-free campus policies on actual conditions of secondhand smoke exposure and risk recognitionamong student nurses

Influence of anti-smoking education and smoke-free campus policies on actual conditions of secondhand smoke exposure and risk recognitionamong student nurses

Study in Real Conditions and in Laboratory of the Application of Expanded Agglomerated Cork as Exterior Wall Covering

The interest of the study on the implementation of expanded agglomerated cork as exterior wall covering derives from two critical factors in a perspective of sustainable development: the use of a product consisting of a renewable natural material – cork – and the concern to contribute to greater sustainability in construction. The study aims to assess the feasibility of its use by analyzing the corresponding behaviour under different conditions. Since this application is relatively recent, only about ten years old, there is still much to learn about the reliability of its long-term properties. In this context, this study aims to deepen and approach aspects, some of them poorly studied and even unknown, that deal with characteristics that will make the agglomerate a good choice for exterior wall covering. The analysis of these and other characteristics is being performed by testing both under actual exposure conditions, on an experimental cell at LNEC, and on laboratory. In this paper the main laboratory tests are presented and the obtained results are compared with the outcome of the field study.

Perturbations in ROS-related processes of the fish Gambusia holbrooki after acute and chronic exposures to the metals copper and cadmium.

Metallic contamination is a widespread phenomena, particularly in areas impacted by human activities, and has become a relevant environmental concern. However, the toxicity of metals on fish requires full characterization in terms of short- and long-term effects. Thus, the purpose of this study was to determine the acute and chronic oxidative stress response in liver and gills of Gambusia holbrooki exposed to copper and cadmium. To assess the effects of these two metals, we adopted a strategy of analyzing the pollution effects caused by salts of the two metallic elements, and we quantified the oxidative stress biomarkers catalase, glutathione reductase, glutathione-S-transferases, and lipid peroxidation after exposure (4 and 28 days) to ecologically relevant concentrations, thus simulating actual conditions of exposure in the wild. Our results showed that copper elicited strong effects in all tested biomarkers for both acute and chronic challenges. Cadmium caused a similar response and was shown to cause significant changes particularly in catalase and glutathione-S-transferases activities. These findings evidence that ecologically relevant concentrations of common anthropogenic contaminants are causative agents of serious imbalances (namely oxidative stress) that are likely to trigger life-threatening events.

A new method for determining the water tightness of building facades

Wind-driven rain and wind pressure are two fundamental climatic parameters affecting the penetration of water through building facades. Water tightness tests attempt to reproduce exposure extremes in order to evaluate the resistance to the passage of water through a facade. However, the exposure conditions for a given return period in a real situation can vary with each location and operating condition. Therefore, standardized test conditions may not be representative of all actual exposure conditions, which prevent a precise evaluation of the facade's performance under operating conditions that differ from test settings. A key challenge for water tightness tests is creating a correlation between standard exposure parameters used in testing and any actual exposure conditions. To address this concern, a new method is proposed that determines the return period associated with the tested exposure for the operating conditions of each facade. The new method is used to assess the adequacy of standardized test exposures (specified by EN 12865:2001 for European localities) on a specific facade at a site in Spain. The method estimates more rigorously the design return period related to water tightness performance of any facade and allows for an improvement of its design using the standardized test results. La pluie battante et la pression du vent sont deux paramètres climatiques fondamentaux affectant la pénétration de l'eau à travers les façades des bâtiments. Les tests d'étanchéité à l'eau tentent de reproduire les conditions extrêmes d'exposition afin d'évaluer la résistance au passage de l'eau à travers une façade. Cependant, les conditions d'exposition pour une période de retour donnée dans une situation réelle peuvent varier avec chaque lieu et chaque condition d'exploitation. Par conséquent, les conditions de test normalisées peuvent ne pas être représentatives de toutes les conditions d'exposition réelles, ce qui empêche une évaluation précise des performances de la façade dans des conditions d'exploitation qui diffèrent des paramètres de test. L'une des principales difficultés pour les tests d'étanchéité à l'eau est d'établir une corrélation entre les paramètres d'exposition standard utilisés pour effectuer les tests et n'importe quelles conditions d'exposition réelles. Pour faire face à cette préoccupation, il est proposé une nouvelle méthode qui détermine la période de retour associée à l'exposition testée pour les conditions d'exploitation de chaque façade. Cette nouvelle méthode est utilisée pour évaluer l'adéquation des expositions des tests normalisés (spécifiées par la norme EN 12865 : 2001 pour les localités européennes) par rapport à une façade spécifique d'un site situé en Espagne. La méthode estime de manière plus rigoureuse la période de retour de conception en lien avec les performances d'étanchéité à l'eau de n'importe quelle façade et permet d'en améliorer la conception en utilisant les résultats des tests normalisés. Mots clés: enveloppe des bâtiments, charges climatiques, conception des façades, paramètres de test, étanchéité à l'eau

Color changes of wood and wood-based materials due to natural and artificial weathering

Color changes of unpainted wood surfaces caused by weathering are an aesthetic problem and the understanding of the underlying processes is a complex task. This study investigates color changes of wooden boards both outdoors on a test house and in the laboratory. The CIE L*a*b* color system is used to compare exposure directions outdoors, laboratory weathering, and materials used in this study. Results indicate that there is a common pattern for color changes. Solar radiation and wind-driven rain are assumed to be the main driving forces behind color changes, together with graying caused by mold growth. However, no quantitative correlation between color changes and the two main climatic strains could be found. Laboratory weathering is a useful tool when it comes to recreate similar exposure conditions. The present study indicates that results from laboratory weathering can hardly be compared to results from outdoor weathering. Though, how close they are to actual exposure conditions is a widely discussed question. However, color measurement is a useful tool to objectively document changes in appearance.

In Vitro Embryotoxicity Testing of Mercury Vapour by Differentiation of ES-D3 Cells

The embryonic stem cell test (EST) is an in vitro assay that has been developed to assess the embryotoxic potential of chemicals and biomaterials. It is based on the capacity of the mouse embryonic stem cell line D3 (ES-D3 cells) to differentiate into contracting myocardial cells. However, the EST method cannot fully test the embryotoxicity of mercury vapor. We tried to apply the rotary culture bottle containing mercury vapor and culture medium was slowly turned and the cells come into direct contact with the gaseous phase containing mercury vapor. At the mercury exposure concentrations tested in this study, no cell pulsations were observed. The cell viability was affected to some extent in the 5.0μg mercury concentration group, whereas in the 2.0μg group little difference was observed from that of the control group. Although mercury vapor was observed to strongly impair the differentiation of EBs in this study, the test results this time did not prove that mercury vapor has a strong embryotoxic effect on humans. We think it important to develop a device that closely mimics the actual exposure conditions of the human body, including an exposure method that is different from that used in this study, as an alternative to animal experiments. .

INTEGRATION OF UNCERTAINTIES INTO INTERNAL CONTAMINATION MONITORING

Potential internal contaminations of workers are monitored by periodic bioassays interpreted in terms of intake and committed effective dose through biokinetic and dosimetric models. After a prospective evaluation of exposure at a workplace, a suitable monitoring program can be defined by the choice of measurement techniques and frequency of measurements. However, the actual conditions of exposure are usually not well defined and the measurements are subject to errors. In this study we took into consideration the uncertainties associated with a routine monitoring program in order to evaluate the minimum intake and dose detectable for a given level of confidence. Major sources of uncertainty are the contamination time, the size distribution and absorption into blood of the incorporated particles, and the measurement errors. Different assumptions may be applied to model uncertain knowledge, which lead to different statistical approaches. The available information is modeled here by classical or Bayesian probability distributions. These techniques are implemented in the OPSCI software under development. This methodology was applied to the monitoring program of workers in charge of plutonium purification at the AREVA NC reprocessing facility (La Hague, France). A sensitivity analysis was carried out to determine the important parameters for the minimum detectable dose. The methods presented here may be used for assessment of any other routine monitoring program through the comparison of the minimum detectable dose for a given confidence level with dose constraints.

Effects of Infrared‐A Irradiation on Skin: Discrepancies in Published Data Highlight the Need for an Exact Consideration of Physical and Photobiological Laws and Appropriate Experimental Settings

Skin exposure to infrared (IR) radiation should be limited in terms of irradiance, exposure time and frequency in order to avoid acute or chronic damage. Recommendations aimed at protecting humans from the risks of skin exposure to IR (e.g. ICNIRP, ACGIH) are only defined in terms of acute effects (e.g. heat pain and cardiovascular collapse), whereas the actual exposure conditions (e.g. spectral distribution, exposure geometry, frequency and number of exposures, thermal exchange with the environment, metabolic energy production and regulatory responses) are not taken into consideration. Since the IR component of solar radiation reaching the Earth's surface is mainly IR-A, and considering the increased use of devices emitting artificially generated IR-A radiation, this radiation band is of special interest. A number of in vitro and/or in vivo investigations assessing cellular or tissue damage caused by IR-A radiation have been undertaken. While such studies are necessary for the development of safety recommendations, the results of measurements undertaken to examine the interaction between skin and IR radiation emitted from different sources presented in this study, together with the detailed examination of the literature reveals a wide spectrum of contradictory findings, which in some instances may be related to methodological shortcomings or fundamental errors in the application of physical and photobiological laws, thus highlighting the need for physically and photobiologically appropriate experiments.

BLIND TESTING OF COMMERCIALLY AVAILABLE SHORT-TERM RADON DETECTORS

A sample of commercially available, charcoal adsorption type, short-term radon detectors was blind tested under controlled laboratory conditions in order to obtain a "snapshot" of the accuracy and precision of the detectors. The results of the controlled exposures were then compared to a previous field study of the same type of commercially available radon detectors. Radon detectors, purchased from seven different commercial vendors, were exposed to a reference (222)Rn gas concentration at the U.S. Environmental Protection Agency's (EPA) Radon Chamber located at the Radiation and Indoor Environments National Laboratory in Las Vegas, Nevada. EPA Test 1 was performed under a controlled simulated field exposure paralleling, to the extent possible, the previous actual field exposure conditions. A second controlled exposure, EPA Test 2, was performed under a relatively steady state of (222)Rn gas concentration, at the same temperature, but a more moderate relative humidity. In the previous field setting evaluation of detectors, five out of six companies tested did not pass the accuracy guideline (all individual relative errors < or =25%) established during the EPA's former Radon Measurement Proficiency Program (EPA-RMPP). As compared to the field test, the detectors in this study generally exhibited better accuracy and precision. Not surprisingly, it appeared temporal fluctuations in radon concentrations and increased humidity had a negative influence on the accuracy and precision of detectors for some companies. The inability of three out of seven companies to meet former EPA-RMPP guidelines for accuracy, even under ideal exposure conditions (constant temperature, humidity, and radon concentration), highlights the importance of blind testing commercially available radon detectors. Furthermore, the consistent over-reporting or under-reporting trends in the overall results for all three tests suggest a potentially widespread systematic bias for the individual companies that merits further investigation. It is unknown if this one-time "snapshot" represents the overall reliability of commercially available charcoal-based radon detectors. Nonetheless, the findings suggest the need for improved vigilance to assure that the public can rely on commercially available radon detectors to make an informed decision whether or not to perform additional testing or to mitigate.

Influence of Heating Envelope on Structural Fire Integrity of Ferrocement Jackets

The structural fire integrity performance of ferrocement jackets was experimentally determined based on its flexural characteristics and the damage after exposure to fire. The main parameter investigated was the heating envelope, consisting of short and long heating durations of 3 and 63 h, where the maximum temperature in both cases was 1060°C. A sandwich-sample configuration was adopted to simulate the actual conditions of exposure to fire. Test results showed that using ferrocement jackets provided a satisfactory solution for fire protection due to improved post-fire strength as compared with that of plain mortar for both heating envelopes. An increase in wire mesh content significantly improved the mechanical properties of ferrocement under normal conditions; however after fire exposure the content of wire mesh was no longer significant regardless of heating duration. It was also found that higher volume fraction of wire mesh resulted in in-plane cracking. Mortar covers had negligible influence on the mechanical properties of ferrocement jacket exposed to fire for both short and long duration. With regard to failure patterns, it was found that long duration heating caused more severe skeletal steel-induced crack but less mortar spalling.

Accuracy in Photo Print Life Prediction

Although the methodology for developing life predictions has been in use for some years in the industry, it is becoming clear that the implied precision in the use of a single value in years cannot be scientifically supported due to much variability between the measurement of an assumed exposure and the actual exposure and observation conditions. All print life predictions assume that the print is exposed to only one condition for its complete life. That is, a light fade prediction assumes no ozone exposure (or exposure to any other industrial gases), and no effects from high or low humidity. Obviously such assumptions are likely to be invalid in almost all real life exposure situations and the data for the long term effects of combined exposures is scant to say the least. This paper examines the implications of this on real life print exposure.