Period Of Continuous Monitoring Research Articles

Dynamic antimicrobial resistance and phylogenomic structure of Salmonella Typhimurium from 2007 to 2019 in Shanghai, China.

Our study uncovered a widespread distribution of Salmonella enterica serovar Typhimurium isolates in Shanghai accompanied by the increase in antimicrobial resistance (AMR) especially MDR during a 10-year period, which filled in the gap about a long period of continuous monitoring of AMR in this pathogen in Shanghai. Meanwhile, we identified a new clade ST34C2 of S. Typhimurium with the acquisition of IncI (Gamma)-like plasmids mediated by extended-spectrum β-lactamase gene blaCTX-M-14 as well as gyrA 87 mutation, which had not been reported before. It was noted that IncI (Gamma)-like plasmids were reported in S. Typhimurium for the first time and conjugation could accelerate the spread of antimicrobial resistance gene blaCTX-M-14. These findings on the epidemic, antimicrobial resistance, and phylogenomic characterization for S. Typhimurium provide valuable insights into its potential risk to public health and also the basis for AMR prevention and control strategies in Shanghai in the future.

Microneedle Assays for Continuous Health Monitoring: Challenges and Solutions.

Continuous health monitoring aims to reduce hospitalization and the need for constant supervision of the patients. For an outpatient monitoring device to be effective, it must meet certain criteria: it should demand minimal patient involvement, be reliable, be connected, remain stable with infrequent replacements, be cost-efficient, be compatible with humans, and ultimately be self-powered. Microneedle (MN) technology, designed for transdermal biosensing, offers a promising solution for meeting a wide range of these demands in the field of continuous health monitoring. A variety of MN platforms have been developed to facilitate this crucial function. Our focus in this Perspective is on the significant challenges linked to MN-based biosensors. These challenges include ensuring skin compatibility, the effective integration of biorecognition elements into the MN systems, and the durability concerns of these sensors in enabling extended periods of continuous monitoring. Tackling these hurdles could pave the way for more effective and reliable MN-based health monitoring solutions in the future.

Assessing rainwater quality in Ca Mau Province: Unveiling the potential and viability for domestic usage

The potential for exploiting rainwater in Ca Mau Province is immense due to its average annual rainfall of 1772 to 2500mm. Over a 15-year continuous monitoring period, the analysis of rainwater quality in Ca Mau Province reveals a prevailing alkaline tendency, with an average pH of 5.90, well within the established raw water quality standards. Concurrently, ongoing groundwater exploitation activities pose a significant threat to the natural aquifer reserves in the region. Recognizing this challenge, rainwater harvesting emerges as a pivotal strategy to alleviate the strain on groundwater extraction. The accumulation of freshwater during the rainy season in Ca Mau, facilitated by household rainwater storage tanks, offers a sustainable solution, ensuring a readily available supply for drinking and cooking needs during the dry season when rainfall is scarce. In addition, average tank capacity to meet the domestic water demand of a 5-member household is 10m3 for the whole year while this number increases to 18 20m3 during the dry years. These rainwater stored in tanks should be treated with chlorine or UV rays before use. Our study provides valuable evidence for policy makers and managers, based on the case study at Ca Mau, to develop a sustainable rainwater management plan for improving the livelihoods of millions people lacking freshwater in coastal zones of the Vietnamese Mekong Delta.

Prediction of atrial fibrillation from at-home single-lead ECG signals without arrhythmias

Early identification of atrial fibrillation (AF) can reduce the risk of stroke, heart failure, and other serious cardiovascular outcomes. However, paroxysmal AF may not be detected even after a two-week continuous monitoring period. We developed a model to quantify the risk of near-term AF in a two-week period, based on AF-free ECG intervals of up to 24 h from 459,889 patch-based ambulatory single-lead ECG (modified lead II) recordings of up to 14 days. A deep learning model was used to integrate ECG morphology data with demographic and heart rhythm features toward AF prediction. Observing a 1-day AF-free ECG recording, the model with deep learning features produced the most accurate prediction of near-term AF with an area under the curve AUC = 0.80 (95% confidence interval, CI = 0.79–0.81), significantly improving discrimination compared to demographic metrics alone (AUC 0.67; CI = 0.66–0.68). Our model was able to predict incident AF over a two-week time frame with high discrimination, based on AF-free single-lead ECG recordings of various lengths. Application of the model may enable a digital strategy for improving diagnostic capture of AF by risk stratifying individuals with AF-negative ambulatory monitoring for prolonged or recurrent monitoring, potentially leading to more rapid initiation of treatment.

Effects of Sediment Dredging on the Reduction in Sediment Internal Loading of Lake Taihu and the Self-recovery Ability of Benthic Organism

Sediment dredging has a great effect on the control of lake internal loading and is one of the important methods for lake internal loading management. In this study, the dredged area of Taihu Lake was used as the main object. An estimation of the reduction in whole lake internal loading of Taihu Lake in decade years was carried out. At the same time, we evaluated the effect of sediment dredging on the control of internal loading in the northern area of Taihu Lake (Zhushan Bay and Meiliang Bay). The results indicated that a total of 42 million cubes of sediment was dredged from Taihu Lake, and the total nitrogen, total phosphorus, and organic matter in the dredged sediment was estimated to be approximately 6.26×104 tons, 1.83×104 tons, and 11.7×105 tons, respectively. This was roughly equal to the 20 years of external loading pollution accumulated in Taihu Lake. From a long-term perspective, sediment dredging could effectively increase the water quality of Meiliang Bay within five years and that where the external loading has been controlled effectively. However, the water quality of Meiliang Bay subsequently rebounded, but dredging still reduced the nitrogen and phosphorus content in surface sediment. On the contrary, dredging could not effectively control the internal loading of Zhushan Bay, which still had a large input of external loading. The amount of sediment internal loading recovered to the original level of the pre-dredging period. In a six-year-long period of continuous monitoring of the benthic organism community of Zhushan Bay, the results indicated that sediment dredging could cause negative effects on sediment dredging initially, but the density and biomass of the benthic organisms in the dredged area had later been recovered to the un-dredged level. There was no difference between the dredged and un-dredged areas with regard to the diversity indices of benthic organisms. The results of this study indicated that sediment dredging can effectively control the lake internal loading. However, the maintenance period of dredging effects was related closely to the input intensity of the external loading. In addition, sediment dredging did not have a large influence on the benthic organism community and could recover to the original level depending on self-recovery.

A critical evaluation of the dynamic nature of indoor-outdoor air quality ratios

Long term, continuous indoor and outdoor pollutant monitoring was evaluated from a case study hospital, school, office and 18 apartments in the UK. Data was examined in order to explore the dynamic behaviour of indoor-outdoor ratios (I/O) for both particulate matter and nitrogen dioxide. Traditionally I/O ratios have been determined as single aggregate values or static parameters, from passive sampling or short periods of continuous monitoring. Whilst widely reported, I/O ratios are seen as too variable to be of wider use. However, this work reveals the dynamic nature of I/O ratios, with strong diurnal and seasonal variation observed for both particulate matter and nitrogen dioxide. Higher I/O ratios tended to be seen during core or occupied hours, associated with increased human activity and higher ventilation rates. This means that static I/O ratios determined by passive sampling techniques, rather than continuous measurements filtered to core hours, may underestimate I/O ratios associated with occupant exposure. Further, the I/O ratio is shown to be strongly influenced by occupant activity and window opening behaviour. As such, it may represent a personal variable as much as one associated with a building. It is argued that traditionally reported static I/O ratios simplify these dynamic behaviour and modes of operation into a single aggregate value, losing key information in the process. Further, without contextual information on the operation and use of a building during measurements a reported I/O ratio may be hard to interpret or compare to wider studies. Finally, it is argued that the I/O ratio, whilst a limited metric, when evaluated dynamically provides a useful building operation parameter, describing the relationship the building has with the outdoor environment. This can help better define ventilation strategies, schedules, the influence of occupant behaviour and significance of indoor sources.

Is Parkinson's Kinetigraph useful in frail patients with Parkinson's disease?

The use of accelerometer device technology in Parkinson's disease allows a period of continuous monitoring giving insight into disease pattern and aiding the optimisation of medication regimens. This service evaluation explores the use of such technology in a geriatrician‐led movement disorder clinic. The authors describe successful use of the Parkinson's Kinetigraph (PKG) in frail older people and discuss how frailty may have implications on the interpretation of the PKG results.

Seasonal variability in a nascent population of a non-indigenous colonial ascidian (Didemnum vexillum) near Winchester Bay, Oregon

The non-indigenous colonial tunicate Didemnum vexillum plagues many shellfish aquaculture operations around the world by smothering crop and gear and displacing juvenile bivalves. There are two populations of D. vexillum in Oregon, but little is known regarding their spatial extent, seasonal dynamics, annual variability, reproductive biology, or ecology. SCUBA divers monitored the seasonal variation and spatial extent of the nascent D. vexillum population in its current foothold at Umpqua Aquaculture, a longline oyster farm adjacent to Winchester Bay, Oregon. From May 2011 to November 2016, divers performed biannual subtidal surveys to measure the cover of D. vexillum on anchor lines. We found that this population of D. vexillum exhibited extensive fluctuation in colony during this period, especially between fall and spring. With one exception, cover was greater in the fall than the spring, though this fluctuation cannot be explained by our proxies for salinity or temperature. Seasonally, on average, D. vexillum covered the greatest proportion of line between 5.5 and 6.0 m depth in both the spring (37.5 ± 18.8%) and fall (45.1 ± 16.1%). During individual surveys, the depth of maximum percent D. vexillum cover was more variable, spanning ~ 4.5–6.5 m depth. Overall, we document a net increase in D. vexillum cover at Umpqua Aquaculture between the first and last surveys during the 5-year period. This study is the first published multi-year analysis of D. vexillum in Oregon and represents the longest continuous monitoring period of an in situ population of D. vexillum to date.

Sugar-Acetic Acid-Ethanol-Water Mixture as a Potent Attractant for Trapping the Oriental Fruit Moth (Lepidoptera: Tortricidae) in Peach-Apple Mixed-Planting Orchards.

Sugar–acetic acid–ethanol–water mixture (SAEWM) trapping has initially shown the potential efficacy for monitoring or trapping insects. It is unknown how SAEWM-baited traps affect field number of oriental fruit moth (OFM), Grapholita molesta (Busck) (Lepidoptera: Tortricidae), the female/male ratio trapped, and the type of natural-enemy insects captured. This study investigated changes in seasonal population dynamics and diurnal flight rhythm of OFM, the number and female/male ratio of OFM and the numbers of Coccinellidae and Chrysopidae trapped by SAEWM in peach–apple mixed-planting orchards. The SAEWM performed well in trapping OFM, most of which were adult females, with the maximum trapping at 2.5 m above ground. The daily trapping peak occurred between 18:00 and 20:00, during each continuous monitoring period, with another peak occurring at 4:00–8:00, after the second monitoring period (2–5 July). However, the use of SAEWM also resulted in the trapping of Coccinellidae and Chrysopidae, of which peak trapping time partially overlapped with the second and third peak trapping times of OFM. We suggest the cessation of SAEWM trapping during the peak activity time of Coccinellidae and Chrysopidae, or application of alternative attractive mixture that do not trap the natural enemy insects, in order to protect the ecological balance in the field.

Towards real-time detection of wastewater in surface waters using fluorescence spectroscopy

The presence of municipal wastewater at the intake of a major drinking water treatment facility located on Lake Ontario was examined using fluorescence data collected during a period of continuous monitoring. In addition, controlled mixing of lake water and wastewater sampled from a local treatment facility were conducted using a bench-scale fluorescence system to quantify observed changes in natural organic matter. Multivariate linear regression was applied to components derived from parallel factors analysis. The resulting mean absolute error for predicted wastewater level was 0.22% (V/V, wastewater/lake water), indicating that wastewater detection at below 1.0% (V/V) was possible. Analyses of sucralose, a wastewater indicator, were conducted for treated wastewater as well as surface water collected at two intake locations on Lake Ontario. Results suggested minimal wastewater contribution at the drinking water intake. A wastewater detection model using a moving baseline was developed and applied to continuous fluorescence data collected at one of the drinking water intakes, which agreed well with sucralose results. Furthermore, the simulated addition of 1.0% (V/V) of wastewater/wastewater was detectable in 89% of samples analyzed, demonstrating the utility of fluorescence-based wastewater monitoring.

Long-term continuous monitoring of the preterm brain with diffuse optical tomography and electroencephalography: a technical note on cap manufacturing.

Diffuse optical tomography (DOT) has recently proved useful for detecting whole-brain oxygenation changes in preterm and term newborns' brains. The data recording phase in prior explorations was limited up to a maximum of a couple of hours, a time dictated by the need to minimize skin damage caused by the protracted contact with optode holders and interference with concomitant clinical/nursing procedures. In an attempt to extend the data recording phase, we developed a new custom-made cap for multimodal DOT and electroencephalography acquisitions for the neonatal population. The cap was tested on a preterm neonate (28 weeks gestation) for a 7-day continuous monitoring period. The cap was well tolerated by the neonate, who did not suffer any evident discomfort and/or skin damage. Montage and data acquisition using our cap was operated by an attending nurse with no difficulty. DOT data quality was remarkable, with an average of 92% of reliable channels, characterized by the clear presence of the heartbeat in most of them.

Research and Monitoring on Conservation State and Preservation Conditions in Unsaturated Archaeological Deposits of a Medieval Farm Mound in Troms and a Late Stone Age Midden in Finnmark, Northern Norway

This paper presents archaeological observations and results of palaeoecological and geo-chemical analyses of archaeological deposits from two rural sites in northernmost Norway. These are combined with climate data and the first period of continuous monitoring of soil temperature, moisture, and redox potential in sections. This data constitutes the basic research material for evaluations of conservation state and preservation conditions. The data has been collected in collaboration with the partners of a cross-disciplinary project: ‘Archaeological Deposits in a Changing Climate. In situ Preservation of Farm Mounds in Northern Norway’ funded by the Norwegian Council for Research (http://www.niku.no/en/archaeology/environmental_monitoring/archaeological_deposits_in_a_changing_climate_in_situ_preservation_of_farm_mounds/). This is an important Norwegian research initiative on monitoring of rural archaeological deposits, and the results have consequences for heritage management of a large number of sites from all periods. Palaeoecological analyses and redox measurements have revealed ongoing decay that might not otherwise have been detected. Decay studies indicate that both site types may be at risk with the predicted climate change. Some mitigating acts are suggested.

Sulfide-driven autotrophic denitrification significantly reduces N2O emissions

The Sulfate reduction–Autotrophic denitrification–Nitrification Integrated (SANI) process build on anaerobic carbon conversion through biological sulfate reduction and autotrophic denitrification by using the sulfide byproduct from the previous reaction. This study confirmed extra decreases in N2O emissions from the sulfide-driven autotrophic denitrification by investigating N2O reduction, accumulation, and emission in the presence of different sulfide/nitrate (S/N) mass ratios at pH 7 in a long-term laboratory-scale granular sludge autotrophic denitrification reactor. The N2O reduction rate was linearly proportional to the sulfide concentration, which confirmed that no sulfide inhibition of N2O reductase occurred. At S/N = 5.0 g-S/g-N, this rate resulted by sulfide-driven autotrophic denitrifying granular sludge (average granule size = 701 μm) was 27.7 mg-N/g-VSS/h (i.e., 2 and 4 times greater than those at 2.5 and 0.8 g-S/g-N, respectively). Sulfide actually stimulates rather than inhibits N2O reduction no matter what granule size of sulfide-driven autotrophic denitrifying sludge engaged. The accumulations of N2O, nitrite and free nitrous acid (FNA) with average granule size 701 μm of sulfide-driven autotrophic denitrifying granular sludge engaged at S/N = 5.0 g-S/g-N were 4.7%, 11.4% and 4.2% relative to those at 3.0 g-S/g-N, respectively. The accumulation of FNA can inhibit N2O reduction and increase N2O accumulation during sulfide-driven autotrophic denitrification. In addition, the N2O gas emission level from the reactor significantly increased from 14.1 ± 0.5 ppmv (0.002% of the N load) to 3707.4 ± 36.7 ppmv (0.405% of the N load) as the S/N mass ratio in the influent decreased from 2.1 to 1.4 g-S/g-N over the course of the 120-day continuous monitoring period. Sulfide-driven autotrophic denitrification may significantly reduce greenhouse gas emissions from biological nutrient removal when sulfur conversion processes are applied.

A prospective clinical trial comparing Biobrane® Dressilk® and PolyMem® dressings on partial-thickness skin graft donor sites

IntroductionIn a single-center, prospective, randomized clinical trial three different configured wound dressings Biobrane®, Dressilk® and PolyMem® were compared with each other regarding objective and subjective healing parameters and cost efficiency. Methods28 burn patients received surgical treatment with split-thickness skin grafting, while utilizing Biobrane®, Dressilk® and PolyMem® as a single bound donor site wound dressing in all patients. Following a standardized case report form, we monitored several parameters such as pain, transparency of the dressing, active bleeding, exudation and inflammation by using the Verbal Rating Scale 1–10 through out. ResultsWith regard to re-epithelialization, pain and acute bleeding all three dressings were equivalent. Dressilk® and Biobrane® presented clearly superior to PolyMem® in both wound assessment and in the reduction of mild inflammation and exudation. High subjective satisfaction rates were reported with Dressilk® and Biobrane® dressings in regard to comfort and mobility. During the continuous monitoring period Biobrane® outperformed Dressilk® by providing higher wound transparency rates and offering a better level of wound control during the entire study period. Regarding their cost efficiency, PolyMem® and Dressilk® are clearly superior to Biobrane®. ConclusionThe “ideal” wound dressing maximizes patients’ comfort while reducing pain and the risk of pulling off migrating epidermal cells from the wound surface. In addition reliable wound status evaluation (minimizing complications), an increase of treatment cost value efficacy, and reduced hospitalization rates should be provided. Dressilk® and Biobrane® were favored by patients and surgeons for providing an effective and safe healing environment, with overall low complication rates with respect to infection and exudation. Regarding cost-effectiveness PolyMem® and Dressilk® presented superior to Biobrane®.

Monitoring of hydraulic fracturing in Moomba, South Australia, using magnetotellurics

The microseismic method is the dominant geophysical tool for monitoring hydraulic fracturing. High-pressure injection of fluids creates fractures in the sub-surface, recorded as small seismic events. Inverting such events yields the temporal and spatial extent of deformation; however, there is no straightforward relationship between the location of micro-deformations and the migration of injected fluid. In this peer-reviewed paper, an alternative approach to deep-fluid monitoring using the magnetotelluric (MT) method is presented. As MT is primarily sensitive to the presence of fluids (through changes in the bulk electrical resistivity) and the orientation of fluid connection, this technique may yield important constraints on how fluids propagate from the well with time. This technique has been successfully used to monitor hydraulically induced fractures in two geothermal settings at depths of more than 3 km. A 10-stage horizontal-well hydraulic-fracture in the Cooper Basin for a shale-gas reservoir was monitored using MT. From the central injecting well, four lines of instruments were placed radially in a cross-pattern. These new electric and magnetic loggers were deployed for a continuous monitoring period of 65 days. As changes in the magnetic field are spatially uniform across the extent of the survey area, only two magnetic-field data recorders were placed in the array. A third logger was placed 10 km from the well, for redundancy and as a remote reference. Measurements were taken from mid-May to mid-July 2014, while the injection and drawback occurred for approximately one month. Processing regimes were created to convert field data into MT responses and resistivity models of the Earth. Theory, survey practice and outputs from this experiment are presented in this peer-reviewed paper.

Nrf2 defense pathway: Experimental evidence for its protective role in epilepsy

Epigenetic mechanisms involved in transcriptional regulation of multiple molecular pathways are potentially attractive therapeutic interventions for epilepsy, because single target therapies are unlikely to provide both anticonvulsant and disease-modifying effects. A selection of epilepsy-related gene expression data sets were retrieved using NextBio software and imported to Ingenuity Pathway Analysis for transcription factor enrichment analysis. Nuclear factor erythroid 2-related factor 2 (Nrf2)-a transcription factor that promotes the expression of numerous antioxidant, anti-inflammatory, and neuroprotective proteins-was identified as a candidate for confirmation of mRNA expression in hippocampal tissue from patients with temporal lobe epilepsy and in mice following pilocarpine-induced status epilepticus (SE). Human Nrf2 was overexpressed via an adeno-associated virus (AAV) vector after the onset of spontaneous recurrent seizures (SRS) in the animals. At the end of a 5-week continuous monitoring period for SRS, quantitative immunohistochemistry using neuronal (neuronal-specific nuclear protein), astrocytic (glial fibrillary acidic protein), and microglial (ionized calcium binding adaptor molecule 1) markers was performed. A significant increase in Nrf2 mRNA expression was observed in human epileptic hippocampal tissue. Nrf2 expression levels increased progressively in mice, reaching a peak at 72 hours after SE, and then declined. Similar expression patterns were observed for 3 Nrf2-regulated genes: HO-1, NQO1, and mGST. Remarkably, mice injected with AAV Nrf2 displayed significantly fewer generalized seizures, with profound reduction in microglia activation. Hippocampal neurons were preserved, whereas the number of astrocytes was unchanged. These findings extend the potential of Nrf2-based therapies to epilepsy and add to the rapidly accumulating evidence from other neurodegenerative and inflammatory disease models.

Continuous deep microseismic monitoring of the Karachaganak Field, Kazakhstan: integrating reservoir geoscience, drilling and engineering

The Karachaganak Field is an oil and gas condensate supergiant field located in the western Kazakhstan Pricaspian Basin. As part of the challenge to improve reservoir knowledge, KPO has been continuously monitoring the reservoir using a microseismic array deployed downhole since February 2009. Continuous deep recording of microseismic activity is an innovative technique for reservoir monitoring; progressive refinements were made to fine-tune the acquisition and processing techniques. By December 2010, 8074 events had been detected and, from this group, 2556 events have been located. Events within the reservoir were recorded up to 8 km from the array to a depth of 5 km with moment magnitudes (Mw) ranging from −2.4 to +1. Microseismic events are continuously located and their spatial and temporal distribution analysed. This basic analysis is the input to an integrated study that considers the static model for the reservoir, in addition to dynamic and operational aspects such as production and injection rates, pressure baffles, drilling behaviour and casing perforations. The results to date indicate valuable reservoir information concerning the location of lateral and vertical reservoir pressure baffles and delineation of zones of instability at the reservoir–seal interface, important for well integrity issues. This new information is helping to improve dynamic and geomechanical reservoir models and also wellbore stability predictions. This article presents the details of the Karachaganak microseismic array and how microseismic events were located. Discussion follows on the interpretation and the possible impact on reservoir monitoring and drilling. The Karachaganak array is one of the deepest installations of a passive microseismic monitoring system and also represents one of the longer periods of continuous monitoring, with two years of data available.

Seismically induced variations in Mariánské Lázně fault gas composition in the NW Bohemian swarm quake region, Czech Republic — A continuous gas monitoring

A continuously operated gas monitoring station was emplaced within the epicentral area of the NW Bohemian swarm earthquakes overlying directly the active Mariánské Lázně fault. The recordings of 8-month continuous monitoring period are presented. The variations in radon concentrations are similarly to variations in CO 2, i.e. CO 2 is considered to be the carrier gas for radon. Very small diurnal variations in gas concentration are caused by the earth tides, as daily variations in meteorological conditions cannot explain a short daily minimum at midday times. Sudden changes in gas concentration, which clearly exceed these diurnal variations occur and are always linked with seismic activities. Decreased gas concentration may indicate compression resulting in reduced fault permeability as is implied by negative peaks following local earthquake swarms. A sudden increase in CO 2 and Rn concentration may indicate an increased fault permeability caused by stress redistribution, giving rise to opening of migration pathways. This implies a repeatedly sudden rise in gas concentration before local earthquake swarms. Several variations in gas concentration were monitored linked with remote earthquakes of ground motion amplitudes >1 μm. These seismic events are accompanied by an interference of the diurnal gas concentration–stress-cycle along the Mariánské Lázně fault. However, if shocks of remote earthquake can alter properties of the migrating fluids or the fault properties it can be suggested that these are able to trigger local seismicity, as indicated in the case of the Slovenia earthquake on 12th July 2004.

The Pulmonary Artery Catheter in Anesthesia Practice

Pressures in the right side of the heart and pulmonary capillary wedge can be obtained by cardiac catheterization without the aid of fluoroscopy. A No. 5 French double-lumen catheter with a balloon just proximal to the tip is inserted into the right atrium under pressure monitoring. The balloon is then inflated with 0.8 ml of air. The balloon is carried by blood flow through the right side of the heart into the smaller radicles of the pulmonary artery. In this position when the balloon is inflated wedge pressure is obtained. The average time for passage of the catheter from the right atrium to the pulmonary artery was 35 s in the first 100 passages. The frequency of premature beats was minimal, and no other arrhythmias occurred.

Consideration of measurement error when using commercial indoor radon determinations for selecting radon action levels

An examination of year-long, in-home radon measurement in Colorado from commercial companies applying typical methods indicates that considerable variation in precision exsts. This variation can have a substantial impact on any mitigation decisions, either voluntary or mandated by law, especially regarding property sale or exchange. Both long-term exposure (nuclear track greater than 90 days), and short-term (charcoal adsorption 4–7 days) exposure methods were used. In addition, periods of continuous monitoring with a highly calibrated alpha-scintillometer took place for accuracy calibration. The results of duplicate commercial analysis show that typical results are no better than ±25 percent with occasional outliers (up to 5 percent of all analyses) well beyond that limit. Differential seasonal measurements (winter/summer) by short-term methods provide equivalent information to single long-term measurements. Action levels in the U.S. for possible mitigation decisions should be selected so that they consider the measurement variability; specifically, they should reflect a concentration range similar to that adopted by the European Community.