Central Monitoring Station Research Articles

Probabilistic Approach and Fuzzy System Based Support of the Railway Stations' Smart Security System

One of the keystones of the smart city is the transportation. The railway is the crucial part in the main public- and also the goods-transportation today, and the significance will be constantly growing. Nowadays the increase in threats and decrease in the sense of security generates a high need for designing smart and multi-level integrated security systems on the railway stations. The security risk of these territories has risen in the last years, because the public transportation plays an important role in the lives of nowadays people and will grow in the future. That means a rise in incidences of robbery, vandalism and even terrorism. The integration of the conventional systems gives more possibility and reliability for the facility management and the end-users to prevent the aforementioned incidences. The power of the complex (human-electrical-mechanical) system can be usable if in the central monitoring station only qualified and well trained operators work. Because of the difficulty of the multi-level integrated security systems, without suitable and well-trained users and operators the efficiency of the security decrease. Furthermore, the efficiency of the complex system can be lower than the unintegrated conventional realizations, so that's why it is needed to integrate special smart functions. Managing the smart complex security systems on the aforementioned railway stations are difficult due the human factor and the large number of connections and internal processes. However, the recently created and improved probabilistic approach- and fuzzy system can be a useful mathematical solution for the aforementioned cases. These methods can be used in the full scaled security system, if first - like the Fuzzy logic - an expert level analysis gives enough information about the crucial parts of the system. With them comes the possibility to give and get data from the determined system, and continuously recalculate the factors and - in some cases - it can also be done online. It helps to generate and send prompt information to the facility management, and with it can maximize the fully functional operational efficiency and reduce the hazards. This article gives a useful guideline for the facility management of the smart cities' railway stations. It declares the main connections with theirs hazards to find the key elements and the in-, and outbound parameters of the smart complex security system. The generated knowledge base will contain also more additional information about the efficiency and the improvement of the system, too.

Source apportionment of non-methane hydrocarbons, NOx and H2S data from a central monitoring station in the Eagle Ford shale, Texas

Unconventional oil and gas exploration in the US has become a significant new source of atmospheric hydrocarbons. Field measurements and monitoring have been initiated to determine integral effects from this geographically dispersed source in and downwind of shale areas, driven mostly by concerns related to photochemical ozone production. The Texas Commission on Environmental Quality (TCEQ) deployed its first air quality monitor near the Eagle Ford shale in south Texas in summer 2013, followed by a more centrally located monitor in winter 2014/15. Here, we report on the latter monitor’s 2015 data, showing at times extraordinarily high levels of saturated hydrocarbons, similar to earlier findings in this area. Using hydrocarbon ratios, we establish that the dominant sources at this site appear to be oil and gas exploration. A non-negative matrix factorization (NMF) analysis revealed six consistent source factors, of which two were associated with pre-existing local sources from car traffic and industry, three with regional oil and gas exploration, and one with diesel emissions. The dominant source factors were associated with evaporative and fugitive emissions, and with flaring and (diesel-powered) compressor engine emissions. The former is a major source of saturated hydrocarbons while the latter is a major source of NOx and unsaturated hydrocarbons, confirming earlier findings. Due to the rural nature of the site, road traffic is a minor NOx source in this area, and the NMF results support inventory estimates showing oil and gas exploration to be the dominant regional source of NOx emissions. The NMF based source apportionment results also suggests that benzene levels in this rural area in 2015, while comparable to levels in Houston now, were probably three to five times lower before the shale boom.

Ozone exposure is associated with acute changes in inflammation, fibrinolysis, and endothelial cell function in coronary artery disease patients

BackgroundAir pollution is a major risk factor for cardiovascular disease, of which ozone is a major contributor. Several studies have found associations between ozone and cardiovascular morbidity, but the results have been inconclusive. We investigated associations between ozone and changes across biological pathways associated with cardiovascular disease.MethodsUsing a panel study design, 13 participants with coronary artery disease were assessed for markers of systemic inflammation, heart rate variability and repolarization, lipids, blood pressure, and endothelial function. Daily measurements of ozone and particulate matter (PM2.5) were obtained from central monitoring stations. Single (ozone) and two-pollutant (ozone and PM2.5) models were used to assess percent changes in measurements per interquartile ranges of pollutants.ResultsPer interquartile increase in ozone, changes in tissue plasminogen factor (6.6%, 95% confidence intervals (CI) = 0.4, 13.2), plasminogen activator inhibitor-1 (40.5%, 95% CI = 8.7, 81.6), neutrophils (8.7% 95% CI = 1.5, 16.4), monocytes (10.2%, 95% CI = 1.0, 20.1), interleukin-6 (15.9%, 95% CI = 3.6, 29.6), large-artery elasticity index (−19.5%, 95% CI = −34.0, −1.7), and the baseline diameter of the brachial artery (−2.5%, 95% CI = −5.0, 0.1) were observed. These associations were robust in the two-pollutant model.ConclusionsWe observed alterations across several pathways associated with cardiovascular disease in 13 coronary artery disease patients following ozone exposures, independent of PM2.5. The results support the biological plausibility of ozone-induced cardiovascular effects. The effects were found at concentrations below the EPA National Ambient Air Quality Standards for both ozone and PM2.5.

Remote Online Performance Evaluation of Photomultiplier Tube and Electronics of DPCAM

Continuous monitoring of the ambient air for the presence of radioactivity is a mandatory requirement in nuclear facilities to be able to initiate prompt actions for the protection of workers from internal exposures. The dual-phosphor scintillator-based continuous air monitor (DPCAM) is an instrument to measure airborne of alpha and beta radioactivities. The functionality of the detector, photomultiplier tube (PMT) along with electronics of DPCAM, is to be tested at periodic intervals to ensure reliability. This paper describes the development of a technique for remote online performance evaluation of PMT along with its electronics, using an LED light source activated from the central monitoring station. A detailed study was made on the response of DPCAM subjected to a pulsed light source of different wavelengths using LEDs. The most suitable LED was selected based on alpha–beta pulse discrimination with zero crosstalk and minimum relative intrinsic error for the full range. The selected LED was fixed on PMT. The DPCAM test circuit was designed and developed for the generation of test frequency to drive this LED. A dedicated radiation data acquisition system was configured using ZigBee wireless network. The remote online performance evaluation of the prototype DPCAM was carried out using loaded filter paper in the field and alpha–beta radioactive sources along with the pulsed light source. The real-time trend graphs generated during the evaluation provides five-point calibration, verification of relative intrinsic error, and verification of crosstalk between alpha–beta channels.

Short-term effects of various ozone metrics on cardiopulmonary function in chronic obstructive pulmonary disease patients: Results from a panel study in Beijing, China.

Short-term exposure to ambient air pollution has been associated with lower pulmonary function and higher blood pressure (BP). However, controversy remains regarding the relationship between ambient multiple daily ozone (O3) metrics and cardiopulmonary health outcomes, especially in the developing countries. To investigate and compare the short-term effects of various O3 metrics on pulmonary function, fractional exhaled nitric oxide (FeNO) and BP in a panel study of COPD patients. We measured pulmonary function, FeNO and BP repeatedly in a total of 43 patients with COPD for 215 home visits. Daily hourly ambient O3 concentrations were obtained from central-monitoring stations close to subject residences. We calculated various O3 metrics [daily 1-h maximum (O3-1h max), maximum 8-h average (O3-8h max) and 24-h average (O3-24h avg)] based on the hourly data. Daily indoor O3 concentrations were estimated based on estimated indoor/outdoor O3 ratios. Linear mixed-effects models were used to estimate associations of various O3 metrics with cardiopulmonary function variables. An interquartile range (IQR) increase in ambient O3-8h max (80.5μg/m3, 5-d) was associated with a 5.9% (95%CI:-11.0%,-0.7%) reduction in forced expiratory volume in 1s (FEV1) and a 6.2% (95%CI:-10.9%,-1.5%) reduction in peak expiratory flow (PEF). However, there were no significant negative associations between ambient O3-1h max, O3-24h avg and FEV1, PEF. An IQR increase in ambient O3-1h max (85.3μg/m3, 6-d) was associated with a 6.7mmHg (95%CI: 0.7, 12.7) increase in systolic BP. The estimated indoor O3 were still significantly associated with reduction of FEV1 and PEF. No significant associations were found between various O3 metrics and FeNO. Our results provide clues for the adverse cardiopulmonary effects associated with various O3 metrics in COPD patients and highlight that O3-8h max was more closely associated with respiratory health variables.

Monitoring Physiological Variables of Mining Workers at High Altitude

Miners working at high altitude must handle extreme climatic and physiological hazards without specialized medical supervision. For this reason, the mining industry is constantly looking for improvements to existing occupational safety and health programs in order to enhance working conditions for people and equipment. This paper presents the design and implementation of a continuous monitoring device to measure the physiological variables of miners at high altitudes (>2000 m.a.s.l.). Extreme environmental conditions are detrimental for human health; therefore, a continuous control of the workers’ vital signs is necessary. The proposed system includes physiological variables such as electrocardiogram, respiratory activity, and body temperature, and environmental variables such as ambient temperature and relative humidity. The noninvasive sensors of the proposed system are embedded all throughout a T-shirt (first layer of protecting clothing) to achieve a functional device and maximum comfort for the users. The device is able to continuously calculate heart and respiration rate, and establish a wireless data transmission to a central monitoring station.

Low-Cost, Robust, and Field Portable Smartphone Platform Photometric Sensor for Fluoride Level Detection in Drinking Water.

Groundwater is the major source of drinking water for people living in rural areas of India. Pollutants such as fluoride in groundwater may be present in much higher concentration than the permissible limit. Fluoride does not give any visible coloration to water, and hence, no effort is made to remove or reduce the concentration of this chemical present in drinking water. This may lead to a serious health hazard for those people taking groundwater as their primary source of drinking water. Sophisticated laboratory grade tools such as ion selective electrodes (ISE) and portable spectrophotometers are commercially available for in-field detection of fluoride level in drinking water. However, such tools are generally expensive and require expertise to handle. In this paper, we demonstrate the working of a low cost, robust, and field portable smartphone platform fluoride sensor that can detect and analyze fluoride concentration level in drinking water. For development of the proposed sensor, we utilize the ambient light sensor (ALS) of the smartphone as light intensity detector and its LED flash light as an optical source. An android application "FSense" has been developed which can detect and analyze the fluoride concentration level in water samples. The custom developed application can be used for sharing of in-field sensing data from any remote location to the central water quality monitoring station. We envision that the proposed sensing technique could be useful for initiating a fluoride removal program undertaken by governmental and nongovernmental organizations here in India.

Wireless sensor networks based smart bin

This article presents the modelling of Wireless Sensor Networks (WSNs) to monitor unfilled level of bins through a central monitoring station and evaluation of wireless links. The nodes, called Wireless Monitoring Unit (WMU) are installed in each and every bins and the sensor present in the WMU measures the unfilled level of the bins and transmit the data to the Wireless Access Point Unit (WAPU). The WAPU receives data from the WMU's and sends the data to the central monitoring station and the level of the bins are monitored by using an application. The current consumption, life expectancy of WMU and WAPU, data transmission distance between WMU and WAPU, wireless link quality and the surface level attainment between the system reading and manual reading have been compared and studied. Based on the obtained results the identified system can be implemented eminently for solid waste management.

Long-term exposure to urban air pollution and lung cancer mortality: A 12-year cohort study in Northern China

Cohort evidence that links long-term exposures to air pollution and mortality comes largely from the United States and European countries. We investigated the relationship between long-term exposures to particulate matter <10μm in diameter (PM10), nitrogen dioxide (NO2), and sulfur dioxide (SO2) and mortality of lung cancer in Northern China. A cohort of 39,054 participants were followed during 1998–2009. Annual average concentrations for PM10, NO2, and SO2 were determined based on data collected from central monitoring stations. Lung cancer deaths (n=140) were obtained from death certificates, and hazard ratios (HRs) were estimated using Cox proportional hazards models, adjusting for age, gender, BMI, education, marital status, smoking status, passive smoking, occupation, alcohol consumption, etc. Each 10mg/m3 increase in PM10 concentrations was associated with a 3.4%–6.0% increase in lung cancer mortality in the time-varying exposure model and a 4.0%–13.6% increase in the baseline exposure model. In multi-pollutant models, the magnitude of associations was attenuated, most strongly for PM10. The association was different in men and women, also varying across age categories and different smoking status. Substantial differences exist in the risk estimates for participants based on assignment method for air pollution exposure.

Respiratory hospital admissions in young children living near metal smelters, pulp mills and oil refineries in two Canadian provinces

BackgroundIndustrial plants emit air pollutants like fine particles (PM2.5), sulfur dioxide (SO2) and nitrogen dioxide (NO2) that may affect the health of individuals living nearby. ObjectiveTo assess the effects of community exposure to air emissions of PM2.5, SO2, and NO2 from pulp mills, oil refineries, metal smelters, on respiratory hospital admissions in young children in Quebec (QC) and British Columbia (BC), Canada. MethodsWe assessed QC, BC and pooled associations between the following estimates of exposure and hospital admissions for asthma and bronchiolitis in children aged 2–4years for the years 2002–2010: i) Crude emission exposures at the residential postal codes of children, calculated by multiplying estimated daily emissions of PM2.5, SO2, or NO2 from all nearby (<7.5km) pulp mills, oil refineries, metal smelters emitting yearly ≥50t and their total emissions, by the percent of the day each postal code was downwind; ii) Daily levels of these pollutants at central ambient monitoring stations nearby the industries and the children's residences. ResultsSeventy-one major industries were selected between QC and BC, with a total of 2868 cases included in our analyses. More cases were exposed to emissions from major industries in QC than in BC (e.g. 2505 admissions near SO2 industrial emitters in QC vs 334 in BC), although air pollutant levels were similar. Odds ratios (ORs) for crude refinery and smelter emissions were positive in QC but more variable in BC. For example with PM2.5 in QC, ORs were 1.13 per 0.15t/day (95% CI: 1.00–1.27) and 1.03 (95% CI: 0.99–1.07) for refinery and smelter emissions, respectively. Pooled results of QC and BC for crude total SO2 emissions from all sources indicated a 1% increase (0–3%) in odds of hospital admissions per 1.50t/day increase in exposure. Associations with measured pollutant levels were only seen in BC, with SO2 and NO2. ConclusionHospital admissions for wheezing diseases in young children were associated with community exposure to industrial air pollutant emissions. Future work is needed to better assess the risk of exposure to complex mixture of air pollutants from multiple industrial sources.

Abstract P059: Telemedicine Data Indicate Short-term Associations Between Clinical Cardiovascular Events and Ambient Particulate Air Pollution

Introduction: Particulate matter (PM) air pollution has been linked to cardiovascular morbidity and mortality with large public health burdens. Although associations between PM and subclinical autonomic and vascular changes have been shown to occur within minutes to hours, studies have been limited in their ability to investigate such short time scales for clinical cardiac events. Accurate onset time is essential for risk estimation of such short exposures, but publically available data lack this information. This study utilized unique telemedicine data to more accurately estimate the short-term effects of PM exposure in triggering acute cardiac events. Hypothesis: We assessed the hypothesis that elevated short-term (1-24 hours) concentrations of coarse PM (2.5 to 10 μm in aerodynamic diameter, PM 10-2.5 ) and fine PM ( &lt; 2.5 μm, PM 2.5 ) in two metropolitan areas in Israel are associated with an increased risk of clinical cardiac events. Methods: We conducted a time-stratified case-crossover study in which cardiac events were identified using time-resolved telemedicine data from the Tel Aviv and Haifa areas, Israel, between 2002 and 2013. Calls to the telemedicine service for cardiac-related symptoms that resulted in an in-home examination by a mobile intensive care and transfer to a hospital were classified into ischemic, arrhythmia, or non-specific events. Onset time was determined by the time of a medical phone call. Ambient pollutant concentrations measured at central monitoring stations were compared between case and control periods using multivariate conditional logistic regression after adjusting for meteorology and other risk factors. We further explored sensitivity for certainty of diagnosis and effect modification by personal characteristics. Results: A total of 7,617 telemedicine subscribers reported 12,661 (20% ischemic, 31% arrhythmic and 49% non-specific) cardiac events that resulted in an evacuation to a hospital over our 12 year period. After adjustment for confounders, a 10 μg/m 3 higher PM 10-2.5 concentration was associated with a greater odds of a clinical cardiac event, with the strongest associations for events due to arrhythmia (OR 1.006, 95% CI: 1.001-1.011) within 12 hours. Similar associations were found at other time points, for ischemic and non-specific cardiac events, as well as for PM 2.5 but these associations often had wider confidence intervals. Risks tended to be higher for subjects who had diabetes, previous ischemic heart disease or were obese, although these differences did not achieve statistical significance. Conclusions: Exposure to PM air pollution over the course of hours may increase the risk of acute clinical cardiac events. Telemedicine allows for more accurate information on event onset and thus can be a powerful tool for epidemiologic studies focusing on short-term exposures to environmental or other stressors.

A low-complexity method based on compressed sensing for long term field measurement of insulator leakage current

Field measurements of insulator leakage current are necessary for long term data storage for research purposes and condition-based maintenance. Long term monitoring and storage of actual waveform are required since the electrical activity on the insulator surface cannot be predicted in advance. This leads to the accumulation of large amount of data. One solution is to optimize the local storage space usage by implementing mathematical tools to eliminate noise and data with low information content. However, the method is computationally intensive and large scale deployment of devices based on such methods is costly. Proper condition-based maintenance cannot be guaranteed without large-scale use of monitoring devices in the field. Thus, the authors propose the use of an alternate low-complexity approach based on compressed sensing that addresses the issue of data size in field measurements. The compressed sensing based technique is perfectly suitable for large-scale deployment of leakage current measurement devices in the context of field monitoring in insulators. The method is structured to deploy low computational burden in the monitoring devices by shifting the entire computational load from the monitoring device in the field to the decoder at the central monitoring station. Different categories of field measured waveforms have been used to demonstrate the performance of the proposed method. It is expected that this paper will contribute to the development of efficient field monitoring devices in insulators.

Harvesting of river flow energy for wireless sensor network technology

River courses play a vital role in preserving unpolluted ecosystems. On the other hand, networks of sensor nodes can be used to measure characteristic parameters in the environment such as temperature, pressure, humidity or the concentration of pollutants. In the framework of the EU FP7 project "GOLDFISH", technical competences of a consortium of 11 institutions are hence employed in designing, manufacturing, validating and operating wireless sensors nodes for tracking pollution in remote rivers. The sensor network is composed of sensor clusters located underwater and gateways on the riverbank with long-distance communication links to the central management and monitoring station. Each sensor node is composed of active electronic devices that have to be constantly powered. Batteries can generally be used for this purpose, but problems may occur when they are to be recharged or replaced, especially in the case of large networks placed in scarcely accessible locations. State-of-the-art energy harvesting technologies can hence constitute a viable powering solution. The possibility to use different small-scale river flow energy harvesting principles is thoroughly studied in this work by the University of Rijeka GOLDFISH team: a miniaturized hydro-generator, a `piezoelectric eel' and a hybrid solution of a rotating shaft plucking a piezoelectric beam. The first two concepts are validated experimentally in a flow channel and in real river conditions. The miniaturized hydro-generator with suitable power management electronics is finally embedded into the wireless sensor node deployed into the river, allowing the GSM transmission of collected data to be successfully performed.

Diseño de un sistema cctv para el monitoreo de los buses articulados de transmilenio usando una red wimax

The Closed Circuit Television (CCTV) system provides an effective tool to increase security within the public bus mass transit system of Bogota’s, Transmilenio; because it provides accessibility to monitor the articulated buses through a combined architecture video surveillance between analog and network, using rolling out a WiMAX network dedicated to this service. This proposal called TmTV, is based on the client-server architecture, mainstay of distributed systems; since all computers and devices on this system operate and deployed transparently in the Central Monitoring Station.

The exposure metric choices have significant impact on the association between short-term exposure to outdoor particulate matter and changes in lung function: Findings from a panel study in chronic obstructive pulmonary disease patients

BackgroundThe use of ambient air pollution data obtained from central air-monitoring stations as surrogates for participants' exposures to outdoor air pollutants in previous studies may have introduced bias in the estimation of exposure–response associations. ObjectivesWe investigated and compared the effects of short-term exposure to outdoor particulate matter (PMout) and outdoor-originated equivalent personal PM (PMeq) on lung function in chronic obstructive pulmonary disease (COPD) patients. MethodsA total of 33 doctor-diagnosed stable COPD patients were recruited and repeatedly measured for lung function (totally 170 measurements) in 2013–2014. Daily PMout concentrations were obtained from central-monitoring stations, and daily time-weighted average PMeq concentrations were estimated based on PMout over the study. Associations of PM with lung function were estimated using mixed-effects models. ResultsInterquartile range increases in PM2.5out (111.0μg/m3, 5-day) and PM10out (112.0μg/m3, 3-day) were associated with a 3.3% (95% confidence interval [CI]: −5.8%, −0.8%) reduction and a 2.1% (95%CI: −3.9%, −0.3%) reduction in forced vital capacity (FVC), respectively. Similar results were found for forced expiratory volume in 1s (FEV1). An interquartile range increase in PM2.5eq (45.3μg/m3, 3-day), but not PM10eq, was still associated with a 1.7% (95%CI: −3.3%, −0.1%) reduction in FVC. ConclusionsOur study may provide a novel approach to assess the association of ambient PM with health observations with improved accuracy.

Computer analysis of foetal monitoring signals

Five systems for computer analysis of foetal monitoring signals are currently available, incorporating the evaluation of cardiotocographic (CTG) or combined CTG with electrocardiographic ST data. All systems have been integrated with central monitoring stations, allowing the simultaneous monitoring of several tracings on the same computer screen in multiple hospital locations. Computer analysis elicits real-time visual and sound alerts for health care professionals when abnormal patterns are detected, with the aim of prompting a re-evaluation and subsequent clinical action, if considered necessary. Comparison between the CTG analyses provided by the computer and clinical experts has been carried out in all systems, and in three of them, the accuracy of computer alerts in predicting newborn outcomes was evaluated. Comparisons between these studies are hampered by the differences in selection criteria and outcomes. Two of these systems have just completed multicentre randomised clinical trials comparing them with conventional CTG monitoring, and their results are awaited shortly. For the time being, there is limited evidence regarding the impact of computer analysis of foetal monitoring signals on perinatal indicators and on health care professionals' behaviour.

Contribution of various microenvironments to the daily personal exposure to ultrafine particles: Personal monitoring coupled with GPS tracking

Exposure to ultrafine particles (UFP) may have adverse health effects. Central monitoring stations do not represent the personal exposure to UFP accurately. Few studies have previously focused on personal exposure to UFP. Sixty non-smoking residents living in Copenhagen, Denmark were asked to carry a backpack equipped with a portable monitor, continuously recording particle number concentrations (PN), in order to measure the real-time individual exposure over a period of ∼48 h. A GPS logger was carried along with the particle monitor and allowed us to estimate the contribution of UFP exposure occurring in various microenvironments (residence, during active and passive transport, other indoor and outdoor environments) to the total daily exposure. On average, the fractional contribution of each microenvironment to the daily integrated personal exposure roughly corresponded to the fractions of the day the subjects spent in each microenvironment. The home environment accounted for 50% of the daily personal exposure. Indoor environments other than home or vehicles contributed with ∼40%. The highest median UFP concentration was obtained during passive transport (vehicles). However, being in transit or outdoors contributed 5% or less to the daily exposure. Additionally, the subjects recorded in a diary the periods when they were at home. With this approach, 66% of the total daily exposure was attributable to the home environment. The subjects spent 28% more time at home according to the diary, compared to the GPS. These results may indicate limitations of using diaries, but also possible inaccuracy and miss-classification in the GPS data.

Does the elemental composition of indoor and outdoor PM2.5 accurately represent the elemental composition of personal PM2.5?

The complex mixture of chemical and elemental constituents that comprise particulate matter (PM) is hypothesized to be, in part, responsible for its toxicity. Epidemiologic studies have identified specific components and sources of PM2.5 associated with adverse health outcomes, but the majority of these studies use the mass concentration of elements in outdoor PM2.5 at central monitoring sites as a surrogate for personal exposure. Personal exposure to PM2.5 and its elemental composition, however, may vary from stationary outdoor measurements. Here, we use concurrent indoor, outdoor, and personal sampling of PM2.5 and its elemental constituents along with personal and home characteristics, collected as a part of the Relationships of Indoor, Outdoor, and Personal Air (RIOPA) study to characterize the differences in PM2.5 among indoor, outdoor, and personal air samples. We found that personal exposure to PM2.5 and most elements were significantly correlated with, though frequently exceeded, both indoor and outdoor measurements. Principal component scores were used to determine that the mixture of elemental components in PM2.5 varies significantly across indoor, outdoor, and personal sample types. Using model-based clustering, we identified 7 clusters of RIOPA participants whose personal PM2.5 samples had similar patterns of elemental composition. Using this approach, two subsets of RIOPA participants were identified whose personal exposure to PM2.5 and elemental concentrations were significantly increased compared to both their indoor and outdoor levels. Collectively, our results suggest that the elemental composition of PM2.5 obtained at central monitoring stations do not accurately represent the overall elemental composition of personal PM2.5 exposure.

Interpretation of the Low-Voltage ECG

Interpretation of the Low-Voltage ECG

Fine and Ultrafine Particle Decay Rates in Multiple Homes

Human exposure to particles depends on particle loss mechanisms such as deposition and filtration. Fine and ultrafine particles (FP and UFP) were measured continuously over seven consecutive days during summer and winter inside 74 homes in Edmonton, Canada. Daily average air exchange rates were also measured. FP were also measured outside each home and both FP and UFP were measured at a central monitoring station. A censoring algorithm was developed to identify indoor-generated concentrations, with the remainder representing particles infiltrating from outdoors. The resulting infiltration factors were employed to determine the continuously changing background of outdoor particles infiltrating the homes. Background-corrected indoor concentrations were then used to determine rates of removal of FP and UFP following peaks due to indoor sources. About 300 FP peaks and 400 UFP peaks had high-quality (median R(2) value >98%) exponential decay rates lasting from 30 min to 10 h. Median (interquartile range (IQR)) decay rates for UFP were 1.26 (0.82-1.83) h(-1); for FP 1.08 (0.62-1.75) h(-1). These total decay rates included, on average, about a 25% contribution from air exchange, suggesting that deposition and filtration accounted for the major portion of particle loss mechanisms in these homes. Models presented here identify and quantify effects of several factors on total decay rates, such as window opening behavior, home age, use of central furnace fans and kitchen and bathroom exhaust fans, use of air cleaners, use of air conditioners, and indoor-outdoor temperature differences. These findings will help identify ways to reduce exposure and risk.