Measurements Of Carbon Monoxide Concentrations Research Articles

Carbon-Monoxide Laser Absorption Spectroscopy Measurements over Ablating Graphite in a Shock Tunnel

Measurements of carbon monoxide (CO) during air–carbon ablation of graphite are performed in the Sandia Hypersonic Shock Tunnel. Resistive heating is used to bring graphite samples to wall temperatures (Tw=1250–1630 K) as measured by an imaging pyrometer. The heated models are subjected to a flow condition of H0=10.6 MJ/kg, Tr(∞)=630 K, P∞=300 Pa, and u∞=4240 m/s. Tunable diode laser absorption spectroscopy measures CO temperature and concentration within the boundary layer at 50 kHz. Ablation product concentrations from experiments are presented as a function of time, including the transient startup of the tunnel. The measured CO concentration increases by approximately a factor of 2 as surface temperatures increase from 1250 to 1630 K. Finally, the CO concentration is observed to be lower than that predicted by several air–carbon ablation models, with the best agreement occurring at the higher surface temperature.

Machine Learning-based Calibration Approach for Low-cost Air Pollution Sensors MQ-7 and MQ-131

Air quality is a vital concern globally, and Sri Lanka, according to WHO statistics, faces challenges in achieving optimal air quality levels. To address this, we introduced an innovative IoT-based Air Pollution Monitoring (APM) Box. This solution incorporates readily available Commercial Off-The-Shelf (COTS) sensors, specifically MQ-7 and MQ-131, for measuring concentrations of Carbon Monoxide (CO) and Ozone (O3) ,Arduino and "ThingSpeak" platform. Yet, those COTS sensors are not factory-calibrated. Therefore, we implemented machine learning algorithms, including linear regression and deep neural network models, to enhance the accuracy of CO and O3 concentration measurements from these non-calibrated sensors. Our findings indicate promising correlations when dealing with MQ-7 and MQ-131 measurements after removing outliers.

The reduction of polynomial degrees using moving average filter and derivative approach to decrease the computational load in polynomial classifiers

Carbon monoxide is a type of pollutant that is harmful to human health and the environment. On the other hand, carbon monoxide also has benefits for industrial matter. Since the benefits and disadvantages of carbon monoxide, the measurement of carbon monoxide concentration is required. The measurement of carbon monoxide level is not easy moreover with low-cost sensors. The usage of 4 sensors namely TGS2611, TGS2612, TGS2610 and TGS2602 has been used along with feature extractor. The polynomial classifier is required to interpret the feature vector into the amount of substance concentration. The common classifier methods suffer fatal limitations. The polynomial classifiers method offers lower complexity in solution and lower computational effort. Since the involvement of a huge number of data points in the modelling process leads to high degree in the polynomial model. The occurrence of Runge's phenomenon is highly possible in this condition. This phenomenon affects the accuracy level of the generated model. The degree reduction algorithm is required to prevent the occurrence of Runge’s phenomenon. The combination of MAF (Mean Average Filter) and derivative approach as degree reductor algorithm has succeeded in reducing the polynomial model degree. The greater the number degree in the model means the greater the computational load. The model degree reductor algorithm has been succeeded to reduce computational load by 96.6%.

A sensitive carbon monoxide sensor for industrial process control based on laser absorption spectroscopy with a 2.3 μm distributed feedback laser

Carbon monoxide (CO) is a ubiquitous atmospheric trace gas produced by natural and anthropogenic sources. It can be used as a quantitative marker to help us understand the different production processes. A near-infrared laser absorption spectroscopy of 2.3 μm based in-situ, real-time and continuous CO sensor equipment is developed for the exhaust pipeline of furnace. High sensitivity is accomplished utilizing the ratio between the second and first harmonic signals detection (WMS-2f/1f). The analyzer is housed in an explosion-proof enclosure and installed at both sides of the pipeline with a diameter of 2.1 m. The measured gas temperature inside the pipeline reaches around 400 K. The results primarily show a more linear response and less error, the measurement precision and the minimum detection limit are 0.42 ppm and 1.29 ppm (1σ), simultaneously. Evaluation of the data suggested a dynamic range from 3.87 ppm to 1.3% based on the 3σ rule and maximum absorbance of one. An operator can analyze the industrial production process clearly, that is, the measured CO concentration is negatively correlated with excess oxygen (O2) by observing the measurement results within 10 h. Meanwhile, the measurements of the real targets show that the sensor has great applicability and potential for exhaust pipeline and combustion control systems.

Dispersi Karbon Monoksida (CO) dari Emisi Transportasi Menggunakan Model Gaussian Line Source di Jalan Jendral Sudirman Pekanbaru

Transportation is the most influential source in increasing levels of carbon monoxide (CO) in the air. Pekanbaru is the capital of Riau province which is experiencing rapid economic development that is a cause of population growth and increasing the number of motorized vehicles. The purpose of this study is to measure CO concentrations from mobile sources then compare them with PP No. 41 of 1999, calculating CO concentrations with the Gaussian Line Source Model, and mapping the predicted distribution of CO emissions on Jalan Jendral Sudirman, Pekanbaru City. The method used is counting the number of motorized vehicles (traffic counting) and measured the concentration of CO and wind speed in the field. The results showed that the highest CO concentration on Jalan Jendral Sudirman Pekanbaru City was on Tuesday with a concentration of 6603.95 µg/m 3 (5.767 PPM) at the sampling point in front of Ramayana Store and 1.4620.3 µg/m 3 at the sampling point in front of Sudirman Square, both concentrations are still below the air quality standard based on PP No. 41 of 1999. From the calculation of the model, the concentration obtained in Ramayana for the measurement distance of 0 m was 27.198 µg/m 3 , at a distance of 5 m was 0.133 µg/m 3 , and at a distance of 10 m was 0.060 µg/m 3 . At Sudirman Square, obtained CO concentrations for the measurement of 0 m is 26.869 µg/m 3 , at a distance of 5 m is 0.131 µg/m 3 , at a distance of 10 m is 0.059 µg/m 3 .

Development of Real-time IoT based Air and Noise Monitoring System

Modernization has brought the world technological advancements, but it has also brought with it a slew of problems. In today's Malaysia, air and noise pollution are becoming more of a concern, along with a rise in occupational disease. A monitoring system is needed to address these issues. This paper describes the development of a real-time IoT-based air and noise pollution monitoring system that can provide monitoring and alert the user to the pollution levels. This monitoring system was built using IoT technology, which included the use of an ESP8266 Wi-Fi Module NodeMCU as a microcontroller to communicate with the chosen IoT analytics platform, ThingSpeak. A gas sensor MQ9 was used to measure carbon monoxide concentrations, and a sound sensor LM393 was used to measure noise levels in the surrounding area. The measured values were displayed on the Arduino software's serial monitor, then sent to the ThingSpeak server and graphically displayed in real time on a screen. The results of the electronic sensors were compared to the results of the stand-alone carbon monoxide meter and digital sound level meter for validation. The proposed monitoring system produced promising results, with 91.12 % and 97.86 % accuracy for gas and sound levels shown by the gas sensor MQ9 and sound sensor LM393, respectively. The framework also provides ThingSpeak server warning messages. When the calculated conditions exceeded the user's defined cap, the server sent the user an email update with the gas and noise limit status. This has made the system more useful and convenient.

Detection Limit of CO Concentration Measurement in LPG/Air Flame Flue Gas Using Tunable Diode Laser Absorption Spectroscopy

In a combustion reaction of hydrocarbon fuel, carbon monoxide (CO) is a gas species that is closely related to air pollution generation and combustion efficiency. It has a trade-off with nitrogen oxide and increases rapidly in case of incomplete combustion or in fuel-rich (Φ > 1) environments. Therefore, it is essential to measure CO concentration in order to optimize the combustion condition. In the case of a steel annealing system, the combustion environment is maintained in a deoxidation atmosphere to prevent the formation of an oxide layer on the steel sheet surface. However, it is difficult to measure the CO concentration in a combustion furnace in real-time because of the harsh environment in the furnace. Tunable diode laser absorption spectroscopy, which has the advantages of non-invasiveness, fast response, and in situ measurement-based optical measurement, is highly attractive for measuring the concentration of a certain gas species in a combustion environment. In this study, a combustion system of a partially premixed flamed burner was designed to control the equivalence ratio for fuel-rich conditions. CO concentration was measured using a distributed feedback laser with a wavenumber of 4300.7 cm−1 in the mid-infrared region. The results showed that the CO concentration measured at an equivalence ratio of 1.15 to 1.50 was 0.495% to 6.139%. The detection limit in the combustion environment was analyzed at a path length of 190 cm and an internal temperature of 733 K. The ranges of the peak absorbance were derived as 0.064 and 0.787, which were within the theoretical bounds of 10−3 and 0.80 when the equivalence ratio was varied from 1.15 to 1.50.

Planar measurements of CO concentrations in flames at atmospheric and elevated pressure by laser-induced fluorescence

The article describes the development and application of a laser-optical technique for the quantitative measurement of carbon monoxide (CO) in combustion environments of elevated pressures relevant of gas turbine environments. Planar CO measurements can provide important information for the understanding of several aspects of the combustion process, such as localized lean blowout conditions or quenching effects of effusion cooling on the combustor flow. While laser-induced fluorescence is a sensitive non-intrusive measuring technique suitable for planar detection, the CO molecule cannot be excited directly in the visible or near UV. For the present implementation, a two-photon excitation scheme with resulting fluorescence in the visible range is utilized. To qualify the technique, planar measurements in a laminar premixed atmospheric flame are performed in a first step; this flame is later on used for calibration of CO concentrations in a laminar premixed flame at elevated pressure up to 5 bar and in a generic turbulent combustor with a swirl-stabilized flame operated at atmospheric pressure. Pressure effects on spectral structures and the calibration procedure are discussed, as well as potential interference by cross-sensitivity with other species. Based on this optimization strategies are defined for the respective experimental arrangements.

What caused the extreme CO concentrations during the 2017 high-pollution episode in India?

Abstract. The TROPOspheric Monitoring Instrument (TROPOMI), launched 13 October 2017, has been measuring carbon monoxide (CO) concentrations in the Earth's atmosphere since early November 2017. In the first measurements, TROPOMI was able to measure CO concentrations of the high-pollution event in India of November 2017. In this paper, we studied the extent of the pollution in India, comparing the TROPOMI CO with modeled data from the Weather Research and Forecasting model (WRF) to identify the most important sources contributing to the high pollution, both at ground level and in the total column. We investigated the period 11–19 November 2017. We found that residential and commercial combustion was a much more important source of CO pollution than the post-monsoon crop burning during this period, which is in contrast to what media suggested and some studies on aerosol emissions found. Also, the high pollution was not limited to Delhi and its direct neighborhood but the accumulation of pollution extended over the whole Indo-Gangetic Plain (IGP) due to the unfavorable weather conditions in combination with extensive emissions. From the TROPOMI data and WRF simulations, we observed a buildup of CO during 11–14 November and a decline in CO after 15 November. The meteorological conditions, characterized by low wind speeds and shallow atmospheric boundary layers, were most likely the primary explanation for the temporal accumulation and subsequent dispersion of regionally emitted CO in the atmosphere. This emphasizes the important role of atmospheric dynamics in determining the air quality conditions at ground level and in the total column. Due to its rapidly growing population and economy, India is expected to encounter similar pollution events more often in future post-monsoon and winter seasons unless significant policy measures are taken to reduce residential and commercial emissions.

Assessment of carbon monoxide exposure in roadside food-vending shanties using coal cookstoves in Kolkata, India

Roadside food-vending shanties using coal cookstoves may be an important source of carbon monoxide (CO) exposure in megacities in India. The shanties are often small, congested and poorly ventilated, and very little is known about the level of human exposure to CO. Here, we assessed the level of exposure to CO in 25 roadside food-vending shanties using coal cookstoves in Kolkata, India. Portable electrochemical CO monitors were used to measure CO concentrations during peak and non-peak customer-periods in closed (blocked from three sides) and semi-closed (blocked from two sides) shanties. Measurements were taken where customers sit indoor about 5–7 ft away from the cookstoves. The shanties' ventilation rates were measured using tracer gas concentration-decay technique. Levels of blood carboxyhaemoglobin (COHb) and exhaled CO were estimated using regression models. The 1-hr time weighted average (TWA) indoor CO exposure levels ranged from 7.8 to 18.1 ppm during peak-periods, and 0.7–3.1 ppm during non-peak-periods. The exposure levels during peak-periods exceeded the USEPA's reference limit of 9 ppm in all cases in the closed shanties, and in 71% of cases in the semi-closed shanties. The ventilation rates ranged from 5.5 to 23.4 and 14.8 to 32.5 cubic feet per minute (cfm) per person for the closed and semi-closed shanties, respectively, indicating poor ventilation in some shanties. There was significant variation (p = 0.01) in the level of indoor CO exposure between peak and non-peak periods, and between shanty types. The estimated levels of blood COHb during peak and non-peak hours were 0.78 ± 0.7% and 0.35 ± 0.07%, respectively, that were within the normal physiological values in non-smokers.

Cavity-enhanced absorption sensor for carbon monoxide in a rapid compression machine

Abstract A sensor based on cavity-enhanced absorption spectroscopy (CEAS) was implemented for the first time in a rapid compression machine (RCM) for carbon monoxide concentration measurements. The sensor consisted of a pulsed quantum cascade laser (QCL) coupled to a low-finesse cavity in the RCM using an off-axis alignment. The QCL was tuned near 4.89 µm to probe the P(23) ro-vibrational line of CO. The pulsed mode operation resulted in rapid frequency down-chirp (6.52 cm−1/µs) within the pulse as well as a high time resolution (10 µs). The combination of rapid frequency down-chirp and off-axis cavity alignment enabled a near complete suppression of the cavity coupling noise. A CEAS gain factor of 133 was demonstrated in experiments, resulting in a much lower noise-equivalent detection limit than a single-pass arrangement. The sensor thus presents many opportunities for measuring CO formation at low temperatures and for studying kinetics using dilute reactive environments; one such application is demonstrated in this work using dilute n-heptane/air mixtures in the RCM. The formation of CO during first-stage ignition of n-heptane was measured over 802–899 K at a nominal pressure of 10 bar. These conditions correspond to the NTC region of n-heptane and such results provide useful metrics to test and compare the predictions of low-temperature heat release by different kinetic models.

Carbon monoxide emission rates from roasted whole bean and ground coffee

ABSTRACTCarbon monoxide (CO) emitted from roasted coffee is a potential occupational respiratory exposure hazard to workers within the coffee industry. The current study objective was to estimate CO emission factors from commercially available roasted whole bean and ground coffee measured in loose form, not packaged, and to assess the utility of CO monitoring in nonventilated storage spaces such as within coffee roasting and packaging facilities, transport vessels, and cafés. Determinants affecting CO emissions from coffee were investigated, including form (whole bean vs. ground), roast level (light, medium, medium-dark, dark), and age (time since the package was opened). CO emission factors were estimated for roasted coffee samples from a variety of manufacturers purchased from local grocery stores and online. Emission tests were performed on 36 brands of coffee, some with more than one sample per brand and with various roast levels. Decaying source equations or smoothing functions were fitted to the CO concentration measurements. Maximum observed emission factors at the peak of the predicted concentration curve were adjusted by the time required to reach the maximum CO concentration and reported as emission factors (EFbuildup). Ground coffee had a significantly increased EFbuildup (P < 0.0001) compared with whole bean. Roast level did not significantly affect emissions for whole bean (P = 0.72) but did for ground (P < 0.001) coffee. For ground coffee, medium-dark and dark roasts had significantly higher emissions than medium and light roasts. Worst-case emission factors from commercially available whole bean and ground coffee measured in loose form, not packaged, showed that roasted coffee can rapidly emit CO. CO concentrations should be monitored in storage spaces in service and manufacturing facilities as well as transport vessels to ensure exposures do not exceed occupational exposure limits. Storage spaces may need to be ventilated to control CO concentrations to safe levels.Implications: Emission rates of carbon monoxide (CO) from roasted coffee showed that unventilated or underventilated storage spaces should be monitored and ventilated, if necessary, to control CO concentrations to safe levels.

CO Imaging in piloted liquid-spray flames using femtosecond two-photon LIF

Abstract Liquid-spray flames are encountered in many practical combustion devices such as gasoline direct injection and diesel engines, gas turbine combustors as well as industrial furnaces. As opposed to gaseous fuels, additional phase-change steps present in liquid sprays not only complicate the overall combustion process, but also make in-situ, laser-based combustion diagnostics challenging. In particular, the formation of carbon monoxide (CO) due to incomplete fuel-air mixing and partial oxidation becomes a major challenge. In this study, we apply femtosecond, two-photon laser-induced fluorescence (fs-TPLIF) to measure CO concentration in piloted liquid-spray flames, taking into account possible signal interferences in the 230.1-nm, B1Σ+←X1Σ+ excitation scheme. A modified, flat-flame McKenna burner fitted with a direct-injection high-efficiency nebulizer (DIHEN) was used to produce piloted liquid-methanol spray flames. Although single-laser-shot OH-PLIF images show the presence of strong turbulent interactions in the core region, shot-averaged OH-PLIF images indicate that near the nozzle-exit region, the primary reaction takes place in an annular region around the droplet cloud, in general. A detailed spectroscopic study reveals that the signal interference at 460 nm originating from the second-order scattering of the excitation laser, which becomes approximately an order of magnitude stronger than CO fluorescence spectral lines near the nozzle exit region. The specific spectral filtering scheme introduced in our recent work is proved to be capable of suppressing interferences primarily originating from C2 Swan-band emissions. Two-dimensional CO maps along with OH-PLIF flame structure data provide key insights into the CO formation in piloted liquid-spray flames, while providing critical validation datasets for advanced computational models.

Development of a tunable diode laser sensor for CO concentration analysis at laboratory-scale conditions for in situ combustion tests of heavy crude oils.

A tunable diode laser-based sensor is reported to monitor carbon monoxide (CO) concentration under conditions similar to those of laboratory-scale tests used to characterize the behavior of heavy crude oil during in situ combustion (ISC). The sensor uses a DFB diode laser operating over the spectral range of the rotational transition R(11) of the first overtone, wherein simulations of spectral absorption bands for CO, CO2, and H2O showed minimal spectral interference. The absorption spectra were calculated using the HiTran 2008 database at temperatures varying between 150°C and 800°C, pressures from 1 to 5atm, and the typical concentration of major species in ISC characterization experiments. The measurements of CO concentration were conducted at ambient temperature and pressure in a static glass cell of borosilicate, with a path length of 3.81cm, to validate the CO sensor architecture under controlled laboratory environments. The calibration curve for CO obtained by quantifying the optical density at the line center of R(11) for a molar-concentration range between 0.7% and 3.4% demonstrated a linear response (coefficient of determination of 0.9986). Experiments at 4atm and 600K were carried out in a custom-designed optical chamber with two optical wedged sapphire windows (2°) to avoid the etalon effect. CO-absorption spectra were validated by a comparative study with the HiTran database, while a calibration-free methodology using scanned-wavelength direct absorption was investigated for future characterizing experiments involving ISC. Signal to noise ratios (SNRs) were above 40 in the optical chamber and higher than 14 in the glass cell. The TDL sensor was also successfully validated during real ISC experiments involving Colombian heavy crude oil. The calibration and oxidation experiments showed the potential of TDL-based sensors in the region of 2.3μm for non-invasive, real-time, and in situ measurements of carbon monoxide generated at similar conditions to those of lab-scale experimental ISC tests.

Assessment of wood burning versus fossil fuel contribution to wintertime black carbon and carbon monoxide concentrations in Athens, Greece

Abstract. The scope of this study was to estimate the contribution of fossil fuel and wood burning combustion to black carbon (BC) and carbon monoxide (CO) during wintertime, in Athens. For that purpose, in situ measurements of equivalent black carbon (eBC) and CO were simultaneously conducted in a suburban and an urban background monitoring site in Athens during the 3 months of winter 2014–2015. For the deconvolution of eBC into eBC emitted from fossil fuel (BCff) and wood burning (BCwb), a method based on the spectral dependency of the absorption of pure black carbon and brown carbon was used. Thereafter, BCwb and BCff estimated fractions were used along with measured CO concentrations in a multiple regression analysis, in order to quantify the contribution of each one of the combustion sources to the ambient CO levels. For a comparative analysis of the results, we additionally estimated the wood burning and fossil fuel contribution to CO, calculated on the basis of their CO ∕ NOx emission ratios. The results indicate that during wintertime BC and CO are mainly emitted by local sources within the Athens Metropolitan Area (AMA). Fossil fuel combustion, mainly from road traffic, is found to be the major contributor to both eBC in PM2.5 and CO ambient concentrations in AMA. However, wintertime wood burning makes a significant contribution to the observed eBC (of about 30 %) and CO concentrations (on average, 11 and 16 % of total CO in the suburban and urban background sites respectively). Both BC and CO from biomass burning (BCwb and COwb, respectively) present a clear diurnal pattern, with the highest concentrations during night-time, supporting the theory of local domestic heating being their main source.

CARBON MONOXIDE INTOXICATION FROM DOMESTIC FUEL-BURNING FURNCACES AND APPLIANCES

The aim of this research paper is to determine if dwellers of rural areas who cook using fuel-burning furnaces and appliances such as woods, charcoal and natural gas are exposed to carbon monoxide (CO) intoxication and to measure the extent of CO intoxication on dwellers resulting from their cooking activities. The data on CO concentration and health problems for this research study were gathered through the means of observation and interview. Samplings were also carried out to measure the CO level at the selected areas, which were identified based on the criteria of the research. These two steps were done concurrently. The measurements of CO in the houses at Kampong Orang Asli Simpang Arang, Gelang Patah residential were taken outside of the houses, inside the kitchen areas before switching the stove on, after the stove was switched on, during the cooking process and after the cooking was completed. The study shows that the dwellers of rural areas who cook using woods as cooking fuels are found to be exposed to CO intoxication and the factors that influence the health risks are duration of cooking activities per meal, frequency of cooking activities, the absence of proper ventilation as well as the amount of CO concentration released during cooking activities. The measured CO concentration from woods during the experiment was in the range of 150 to 500 ppm. Through CO samplings of charcoal and natural gas as control experiments, it is also found that both sources did not contribute to any serious health effects to the people using them as cooking fuels. Meanwhile, the average CO toxicant produced from burning woods was the highest and this indicates that the CO level from woods is the most risky one among the other domestic fuels commonly used.

Measured carbon monoxide concentrations from stock and reduced-emission prototype portable generators operated in an attached garage

ABSTRACTThere is concern about the hazard of acute residential CO exposures from portable gasoline-powered generators, which can result in death or serious adverse health effects in exposed individuals. To address this hazard, the U.S. Consumer Product Safety Commission has developed low CO emission prototype generators by adapting off-the-shelf emission control technologies onto commercially available generators. A series of tests was conducted to characterize the indoor CO concentrations resulting from portable generators operating in the attached garage of a research house under seven different test house/garage configurations. The tested generators include both unmodified and modified low CO emission prototypes. It was found that CO concentrations varied widely, with peak house CO concentrations ranging from under 10 ppm to over 10,000 ppm. The highest concentrations in the house resulted from operation of the unmodified generator in the garage with the garage bay door closed and the house access door open. The lowest concentrations resulted from operation of a modified low CO emission prototype in the garage with the garage bay door open and the house access door closed. These tests documented reductions of up to 98% in CO concentrations due to emissions from two low CO emission portable generators compared to a stock generator.Implications: Improper portable generator use has caused 800 U.S. deaths in the past 14 years. Generators operated in attached garages can cause CO to quickly reach deadly levels. Two low-emission prototypes generators were tested and had CO emissions reduced by up to 98%. Low-emission generators can reduce the risk of consumer poisonings and deaths.

Industrial-scale investigations of anthracite combustion characteristics and NOx emissions in a retrofitted 300 MWe down-fired utility boiler with swirl burners

To burn anthracite and reduce NOx emissions, a new combustion system was applied to a 300 MWe Babcock & Wilcox (B&W) down-fired boiler that included overfire air (OFA) and a decreased flow area of the inner and outer secondary air ducts of the installed swirl burners. Industrial-scale measurements (adjusting OFA ratios from 15.4% to 22.6%) were conducted to evaluate the overall performance of the retrofitted boiler. The experimental results demonstrated that the new combustion system promoted coal/air flow ignition and combustion stability. When the OFA ratio was less than 19.7%, the influence of the burner secondary air ratio on coal/air flow ignition was greater than that of the recirculation region below the arches. The overall combustion level in the primary combustion zone depended on the oxygen content and the recirculation region in the lower furnace instead of the early or late ignition of the coal/air flow. Oxygen and carbon monoxide concentration measurements in the near-sidewall region revealed that the fullness degree of the coal flame varied under different OFA ratios. Considering both environmental and economic effects, 19.7% was chosen as the optimal OFA ratio, thereby achieving a significant NOx reduction of 47% without increasing carbon content in the fly ash.

Comparison of optical-feedback cavity-enhanced absorption spectroscopy and gas chromatography for ground-based and airborne measurements of atmospheric CO concentration

Abstract. We present the first comparison of carbon monoxide (CO) measurements performed with a portable laser spectrometer that exploits the optical-feedback cavity-enhanced absorption spectroscopy (OF-CEAS) technique, against a high-performance automated gas chromatograph (GC) with a mercuric oxide reduction gas detector (RGD). First, measurements of atmospheric CO mole fraction were continuously collected in a Paris (France) suburb over 1 week. Both instruments showed an excellent agreement within typically 2 ppb (part per billion in volume), fulfilling the World Meteorological Organization (WMO) recommendation for CO inter-laboratory comparison. The compact size and robustness of the OF-CEAS instrument allowed its operation aboard a small aircraft employed for routine tropospheric air analysis over the French Orléans forest area. Direct OF-CEAS real-time CO measurements in tropospheric air were then compared with later analysis of flask samples by the gas chromatograph. Again, a very good agreement was observed. This work establishes that the OF-CEAS laser spectrometer can run unattended at a very high level of sensitivity ( &lt; 1 ppb) and stability without any periodic calibration.

Correlation between clinical severity and different non-invasive measurements of carbon monoxide concentration: A population study.

ObjectivesCarbon monoxide (CO) poisoning is a major concern in industrialized countries. Each year, thousands of victims, resulting in approximately 100 fatalities, are encountered in France. The diagnosis of CO poisoning is challenging; while carboxyhemoglobin (COHb) may be useful, it is a weak indicator of the severity of CO poisoning. This weak indicator may be a result of the delay between poisoning occurrence and the blood assay. Two apparatuses, CO oximeters and exhaled CO analyzers, now permit COHb to be determined outside hospitals. Our hypothesis is that these instruments allow the early measurement of COHb concentrations, which are more correlated with the severity of poisoning, expressed using the poisoning severity score (PSS).DesignIn an observational and retrospective cohort study, the distribution of COHb measurements obtained by CO oximetry or by exhaled CO analyzers was compared between groups of severity expressed using the PSS.SettingData were collected in the Paris area from January 2006 to December 2010 by the French Surveillance System of CO poisoning.ParticipantsAll patients with CO poisoning reported to the French Surveillance System of CO poisoning.ResultsThere was a significant difference in the COHb values obtained by CO oximetry between groups stratified according to PSS (p<0.0001). A significant difference in the values of exhaled CO was also observed between PSS groups (p = 0.006), although the relationship was not linear.ConclusionsThe COHb concentrations measured using CO oximetry, but not those measured using exhaled CO analyzers, were well correlated with the severity of CO poisoning.