Maximum Carbon Monoxide Concentration Research Articles

Detached eddy simulation of traffic-induced air pollution in an urban highway with complex surrounding morphology

Air pollution caused by traffic is a major contributor to unhealthy ambient air quality in the vicinity of urban highways and puts the health of residents and pedestrians at risk. Therefore, it is imperative to examine local pollution reduction methods. The present paper is concerned with Detached Eddy Simulation (DES) of an urban area with high concentration of air pollutants. As an example of a complex surrounding morphology, the studied domain encompasses a 2.5 km stretch of high-traffic highway, a bus terminal, and the nearby residential buildings. The numerical procedure is validated with some benchmark wind tunnel and numerical data. The locations of pollution accumulation have been identified and the effect of the ambient wind speed on the change of the maximum pollution concentration points has been investigated. Furthermore, potential pollution reduction strategies for such complex morphologies have been proposed based on the geometry change to prevent the formation of critical zones of pollution accumulation. The results show that critical zones are generally formed behind the walls of upstream buildings, adjacent to the upstream wall of the highway, and in front of the walls of downstream buildings. It was also found that changes in the ambient wind speed do not significantly alter the location of these critical zones. Furthermore, increasing the distance between adjacent buildings and the highway from 21 m to 30 m, can result in an average reduction of 76% in maximum carbon monoxide concentration values. An investigation into the impact of upstream buildings height indicates that reducing the height of certain buildings can effectively diminish pollution concentration to zero in residential areas and surrounding sidewalks. Additionally, increasing the depth of the highway and erecting 2 m solid barriers on either side of the highway are identified as two other effective techniques for reducing pollution concentration on both sides of the highway. The findings can be utilised to develop novel strategies aimed at enhancing air quality for residents and pedestrians.

Household carbon monoxide (CO) concentrations in a large African city: An unquantified public health burden?

Carbon monoxide (CO) is a poisonous gas produced by incomplete combustion of carbon-based fuels that is linked to mortality and morbidity. Household air pollution from burning fuels on poorly ventilated stoves can lead to high concentrations of CO in homes. There are few datasets available on household concentrations of CO in urban areas of sub-Saharan African countries. CO was measured every minute over 24 h in a sample of homes in Nairobi, Kenya. Data on household characteristics were gathered by questionnaire. Metrics of exposure were summarised and analysis of temporal changes in concentration was performed. Continuous 24-h data were available from 138 homes. The mean (SD), median (IQR) and maximum 24-h CO concentration was 4.9 (6.4), 2.8 (1.0–6.3) and 44 ppm, respectively. 50% of homes had detectable CO concentrations for 847 min (14h07m) or longer during the 24-h period, and 9% of homes would have activated a CO-alarm operating to European specifications. An association between a metric of total CO exposure and self-reported exposure to vapours >15 h per week was identified, however this were not statistically significant after adjustment for the multiple comparisons performed. Mean concentrations were broadly similar in homes from a more affluent area and an informal settlement. A model of typical exposure suggests that cooking is likely to be responsible for approximately 60% of the CO exposure of Nairobi schoolchildren. Household CO concentrations are substantial in Nairobi, Kenya, despite most homes using gas or liquid fuels. Concentrations tend to be highest during the evening, probably associated with periods of cooking. Household air pollution from cooking is the main source of CO exposure of Nairobi schoolchildren. The public health impacts of long-term CO exposure in cities in sub-Saharan Africa may be considerable and should be studied further.

Spatiotemporal distribution of carbon monoxide dynamics and probabilistic health risk assessment: A comprehensive sensitivity analysis across India's state capitals

Carbon monoxide (CO) is a harmful trace gas produced from the incomplete combustion of fossil fuels. Carbon monoxide (CO) poses a substantial threat to human health. The objectives of this study were to investigate carbon monoxide (CO) annual and seasonal variations with meteorological factors, study the marginal effects of weather factors on CO, analyze the impact of independent variables (meteorological factors) importance on CO distribution, time series trend analysis (Mann-Kendall and Sen's slope, additive decomposition model, and linear trend model), study the spatial distribution of CO in the capital cities and non-carcinogenic health risk in India from 2019 to 2022. The study showed that CO concentrations varied, notably across different years (from 2019 to 2022), months, and seasons. The maximum annual CO (0.91 ± 0.17 mg/m3) concentration was recorded in 2019, while the lowest was (0.67 ± 0.12 mg/m3) in 2022. Seasonally, the winter season had the highest load of CO (ranging from 0.17 to 2.17 mg/m3) in the ambient atmosphere compared to the monsoon (0.08 to 1.38 mg/m3) and summer (0.10 to 1.50 mg/m3) seasons. The analysis of the importance of the independent variables (meteorological factors) on CO indicated that temperature had the most substantial impact on CO variation, followed by wind direction, relative humidity, and wind speed. The trend analysis using different models showed a declining trend in CO concentrations over the study period. The non-carcinogenic health risk HQ values were less than 1, suggesting no notable risk. The Monte Carlo simulation revealed that the 5th and 95th percentile range of HQ risk was 0.02 to 0.07 and the sensitivity analysis of non-carcinogenic risk at the state capital level was conducted, and revealed that Delhi was at a higher risk than Chandigarh, Patna, Gandhinagar, Bengaluru, Mumbai, and others, respectively. The results of this study on CO emissions will be beneficial in creating focused plans and policies to reduce CO pollution in seasonal influences and its effects on ambient air quality and public health in the capital cities of Indian states.

WORKPLACE EXPOSURE MONITORING AND MORBIDITYPATTERN OF WORKERS EMPLOYED IN HIGHWAY TOLL PLAZA

At the toll plaza, vehicle operation, including acceleration and deceleration, emit more pollutants and takes longer to cross the area, with the highest level of pollution being generated during this period. As a result, the workers are exposed to numerous sorts of pollution for an extended periodof time throughout their workday. In the present study, we monitored probable contaminants inside the toll plaza in order to assess the morbidity conditions of these individuals as a result of chronic exposures at the workplace. Personal measurements of particulate matter (PM), total volatile organic carbons (VOCs) and carbon monoxide (CO), and polyaromatic hydrocarbons (PAHs)-particulate phase were considered to determine exposure. The mean work shift dustconcentration of PM2.5 and PM10 readings were within the permissible level of Indian standards (PM2.5 60 μg/m3 and PM10 100 μg/m3) but exceed the WHO recommended guideline (PM2.5 15 μg/m3and PM10 45 μg/m3). The maximum CO concentration was 2.65 ppm, while the lowest was 0.31ppm.Lesser aerodynamic particulate matter of PM1 and PM4 and gases, which were monitored, have norecognised standards. H2S concentrations ranged from 0.06 to 2.00 ppm, while VOC concentrations ranged from 0.08 to 0.41ppm. Total PAHs were found in the range of 2.10-24.81 μg/m3 and Benzo [] Pyrene (BaP) was identified in the range of 2.10-7.60 g μg/m3 in each sample. Headache (66 %), back pain (60.4 %), coughing (54.7 %), hair fall (41.5%), tearing (32.2 %), itching eyes (32.2 %), joint pain (28.3 %), congestion in the nose (17%), sore throat (%), and neck pain (15.1 %) were the mostcommon health problems reported by toll plaza workers.

Variability in the UTLS chemical composition during different modes of the Asian Summer Monsoon Anti-cyclone

The Asian Summer Monsoon Anticyclone (ASMA) is an important circulation in the upper troposphere and lower stratosphere (UTLS) region during the boreal summer. The center of the ASMA is not a stationary feature but oscillates between longitudes 50°-92.5°E showing different modes. The ASMA center oscillating over 50°-67.5°E, 80°-92.5°E and 67.5°-80°E are termed as IP (Iranian Plateau), TP (Tibetan Plateau) and Elongated mode, respectively. This work explores the spatial variability and the influence of the background dynamical conditions on the vertical chemical distribution of carbonmonoxide (CO), water vapor (WV) and ozone (O3) in the UTLS region during the different ASMA modes using MLS satellite and NCEP/NCAR reanalysis observations. MLS observations for the period 2010–2018 showed maximum CO, WV and minimum O3 concentrations at 100 hPa in the ASMA center over the respective IP, TP and elongated modes. Enhancement in the tropospheric tracers (CO and WV) throughout the upper troposphere during TP and Elongated mode is observed indicating the transport of boundary layer air to the UTLS region from across these regions. In contrast, the enhancement in the tropopause region during the IP mode is mainly due to the convective lifting over the Tibtean plateau longitudes and strong horizontal advection towards the IP longitudes. Our study also revealed that the vertical transport of the tropospheric tracers to the stratosphere is effective over Tibetan Plateau irrespective of the ASMA mode. The warmer tropopause temperature due to an increase in O3 concentrations over the TP supported the vertical transport of WV to lower stratosphere over this region irrespective of the ASMA mode.

Carbon monoxide concentration in mainstream E-cigarette emissions measured with diode laser spectroscopy

The e-fluid heated in electronic cigarettes (e-cigarettes) is largely composed of organic compounds, specifically propylene glycol, vegetable glycerin and flavouring compounds. When heated, as it is in an e-cigarette, the...

Assessment of carbon monoxide concentration in indoor/outdoor air of Sarayan city, Khorasan Province of Iran.

Nowadays, air pollution by humans is considered a serious problem. One of the main sources of air pollution is carbon monoxide which is called the silent killer. With the increasing rate of population growth in Iran and subsequent acceleration of vehicle and fossil fuel usage, the mortality rate of carbon monoxide has increased. The aim of this study is assessment of the concentration of carbon monoxide in indoor and outdoor air of Sarayan city, Khorasan Province of Iran. In this descriptive-analytic study, the air condition of a residential area and outdoor environment of Sarayan city has been monitored for determining the carbon monoxide concentration during a 3-month period from January to March 2017. Overall, 25 stations with uniform distribution were located in the city. Fifty samples were taken monthly and by considering 3-month period, a total of 150 samples were gathered. The samples were taken in kitchens between 11a.m. and 3p.m., and by considering the respiratory height of the human body, the carbon monoxide meters (TES model, Taiwan) were placed at a height of 75-150cm. The descriptive statistics were presented after entering data into SPSS-16, and, by applying Mann-Whitney and Kruskal-Wallis tests in the case of α = 0.05, the data were analyzed. The average concentrations of carbon monoxide in indoor and outdoor environments were 0.84 ± 3.21ppm and 0.27 ± 0.92ppm, respectively. The maximum carbon monoxide concentration in February in an outdoor environment was 6ppm (station no. 4) and the least one was 0ppm. In March, for an indoor area, the maximum carbon monoxide concentration was 41pm for station no. 11. The indoor-to-outdoor (I-to-O) ratio in March was higher than other months, and in January, was less than others. The study reveals that the indoor and outdoor carbon monoxide indices of Sarayan city are at acceptable levels.

Dispersion modelling of carbon monoxide and total suspended particulate emission from cement stacks: case study of PT. Semen Tonasa in Indonesia

<p class="abstract"><strong>Background:</strong> Industrial activities in the cement production process produce emissions in the form of carbon monoxide (CO) and total suspended particulate (TSP) which have potential to cause environmental pollution in settlements around the industrial area. This study aimed to estimate the distribution emissions of CO and TSP concentrations at six settlements location around PT. Semen Tonasa of Pangkep Regency in a year.</p><p class="abstract"><strong>Methods:</strong> This observasional study was conducted by using descriptive approach. This study was conducted on May–June 2018. Meterological data used for this study were air temperature, solar radiation, wind direction, and wind speed in 2014–2017 collected from Maros Climatology Station and data about seven main stack characteristics in 2014–2017 were collected from environmental services of South Sulawesi Province. </p><p class="abstract"><strong>Results:</strong> The highest CO and TSP concentrations predicted in each location were respectively, 17.02 μg/m<sup>3</sup> and 6.56 μg/m<sup>3</sup> at Bontoa, 27.52 μg/m<sup>3</sup> and 10.4 μg/m<sup>3</sup> at Taraweang, 443.65 μg/m<sup>3</sup> and 148.41 μg/m<sup>3</sup> at Masjid Taqwa, 22.21 μg/m<sup>3</sup> and 3.1 μg/m<sup>3</sup> at Biringere, 1.17 μg/m<sup>3</sup> and 1.36 μg/m<sup>3</sup> at Kampung Sela, 19.07 μg/m<sup>3</sup> and at 15.54 μg/m<sup>3</sup> at Mangilu.</p><p class="abstract"><strong>Conclusions:</strong> The dominant direction of CO and TSP dispersion was from the west. The highest concentrations were predicted at Masjid Taqwa in the most month. Maximum CO and TSP concentrations were not higher than the local regulation. Thus, it can be concluded that CO and TSP emissions from the cement plant have no impact on health in nearby communities.</p>

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.

Transient analysis of carbon monoxide transport phenomena and adsorption kinetics in HT-PEMFC during dynamic current extraction

This paper investigates the transport phenomena of carbon monoxide (CO) and adsorption kinetics, in a high-temperature proton exchange membrane fuel cell (HT-PEMFC) during step-wise current extraction (step-change in current extraction). Step-wise current extraction is a common process done to accommodate a sudden power surge during an operation. Since HT-PEMFCs are capable of handling high impurity of CO, hydrogen fuel that is contaminated with trace amount of CO is usually considered for commercial benefits. Thus, a transient three-dimensional isothermal anodic electro-kinetic numerical model is developed to determine the effect of operating parameters such as fuel cell temperature, CO inlet (initial) concentration, step-change of current density and dwell time on the transport phenomena of CO and adsorption kinetics. In addition, geometrical factors such as the catalyst layer (CL) and gas diffusion layer (GDL) porosity are also varied as well. The results show that the above-mentioned operating parameters can affect the maximum CO concentration at the CL, especially at the outlet of the channel. Specifically, a reduction of fuel cell temperature can significantly increase the CO concentration near the outlet, while increasing CO inlet (initial) concentration, step-change amplitude of current density and current density dwell time can cause an increase in CO concentration at the outlet, albeit to different extent. In addition, the increase in the porosity of CL and GDL, results in the reduction of the maximum CO concentration at the outlet, albeit to different extent. In addition, the CO and hydrogen surface coverage fractions are also affected by the variance of the above mentioned parameters.

Experimental study on vertical RPU fire suppression performance using water spray

A series of vertical fire suppression experiments are conducted using rigid polyurethane (RPU) material of dimensions 60×30×2cm in the standard combustion chamber. Four different kinds of water spray fluxes (66.7, 80, 90, 100ml/min) and two different spray angles (0° and 30°) are used to suppress wind-aided RPU fire. The thermal radiation, carbon monoxide concentration and smoke concentration are measured with water spray being applied or not. The results show that both of the maximum radiation and maximum smoke concentration appear to have minimum values with 90ml/min water spray flux and 0° water spray angle. In addition, all the obtained values of the maximum radiation, maximum carbon monoxide concentration, extinguishing time and maximum smoke concentration with 0° spray angle are larger than those with 30° spray angle with the same water spray flux. That is, for the same water spray flux, the suppression effect with 30° spray angle is better than that with 0° spray angle.

A novel evacuation passageway formed by a breathing air supply zone combined with upward ventilation

With the development of transportation, the tunnel has become one of the important facilities of railway, highway and subway transportation. However, fire hazards occurring inside the tunnel may incur huge numbers of casualties and property losses. In this paper, a breathing air supply zone combined with an upward ventilation assisted tunnel evacuation system (BTES) is introduced. It can be used to create a safe, smoke-free evacuation passageway out of the tunnel. The BTES is optimized to achieve high-performance. The impacts of heat release rates, fire source locations and fire detection times are also discussed.The carbon monoxide (CO) concentrations found when utilizing the BTES were significantly lower than that found when utilizing the traditional ventilation system. An obvious, clean evacuation passageway was created by the BTES. The maximum CO concentrations in the BTES evacuation passageway were below 10 PPM throughout the entire combustion process. A larger CO concentration gradient in the vertical direction was detected with the BTES than that found in other ventilation systems. This finding means that the lower part of the tunnel has a lower CO concentration with the BTES, which benefits the evacuation process. The impacts of fire source locations and fire detection times were tested to ensure the system reliability, and it was found that the performance of the BTES was not sensitive to them.

One-day-ahead prediction of maximum carbon monoxide concentration in urban environments

The adverse health effects associated with exposure to CO range from the more subtle cardiovascular effects at low concentrations to death after acute or chronic exposure to higher concentrations. The forecasting of the daily CO maximum levels is therefore essential in every attempt for protecting and improving public health in urban areas. The objective of this work is to create a suite of statistical models for predicting the one-day-ahead maximum CO levels based on both the meteorological and the pollutant data recorded in six monitoring sites in the greater area of Athens, Greece. The meteorological variables used as input consist of hourly values of the surface air Temperature, the Relative Humidity, the Wind Speed and the Wind Direction, while the pollutant parameters consist of hourly concentrations of nitrogen oxide, nitric dioxide, ozone and sulfur dioxide, all corresponding to the 7-year-period between 2001 and 2007. The models were developed on a seasonal (warm vs. cold period) and hebdomadal (workdays vs. weekends) basis and revealed that the influence of the air pollution levels recorded one day before (day m−1) on the maximum CO concentrations of day m is quite variable and depends on the site/type of the station, the local meteorology and the emission sources. Additionally, the analysis revealed that the CO concentrations are influenced by both local and/or wider area CO sources, suggesting a strong persistence of the CO levels, while only local meteorology (e.g. in the vicinity of the station and especially during working days) plays a role in the formation of present day’s CO levels. The derived models were validated against an independent yearlong data set (2008) through the use of a classical set of validation parameters known as the Model Validation Kit. Indices assessing the ability of the models to predict the CO exceedances of the EC limit value were also used. On the whole, it was found that the prognostic models introduced here manage to predict the CO maximum daily values in a satisfactory level, with Pearson’s correlation coefficients ranging between 0.62 and 0.76 during the warm period and between 0.51 and 0.80 during the cold period of the year. Similarly the index of agreement ranges between 0.50–0.95 during the warm period and 0.57–0.81 during the cold period of the year, revealing a rather adequate model performance.

Emission of Carbon Monoxide During Composting of Municipal Solid Waste

Elevated concentrations of carbon monoxide (CO) have been observed at the enclosed municipal waste composting facility (ECF) in Edmonton, Canada. Elevated concentrations of CO in an enclosed facility pose a potential health risk to workers. The objectives in this study were to: (1) assess temporal and spatial variability of CO emissions from the composting bays in the ECF using Fourier Transform Infrared (FTIR) spectroscopy; and (2) identify any correlations between the CO emission rate and the physicochemical properties of the compost through bench-scale incubation experiments. Repeated gas measurements were taken above and within the compost bed in the ECF using a probe connected to an FTIR gas analyzer, which continuously collected concentration data. These preliminary field measurements showed maximum CO concentrations of 112 μL−1 within the compost. Autoclaved and non-sterilized compost samples from the ECF were incubated under aerobic and hypoxic conditions, and gas emissions were quantified using gas chromatography (GC). These trials showed a positive correlation between CO emission rate and incubation temperature for all samples, indicating a physico-chemical source of CO generation. Lower concentrations of CO were observed in the non-sterilized compost under both aerobic and anaerobic conditions, presumably due to the microbial metabolism of CO.

Air Quality and Cardiovascular Health

Ambient particulate matter has been associated consistently with an increased risk for mortality largely due to cardiovascular diseases.1 Although the relative risk estimates from epidemiological studies are small, they apply to almost the entire population of the United States. Consequently, exposure to ambient particles produces considerable burden of disease, and its mitigation offers the benefit of improving life expectancy.2 Articles see pp 941 and 949 Over the past decade, research has substantiated the understanding of the pathophysiological mechanisms linking ambient particles to the cardiovascular system3,4 once it was noted that ambient air pollution elicits systemic inflammatory responses in the general population.5 An update of the American Heart Association statement on air pollution and cardiovascular disease3 is under way. Mechanisms considered for active and secondhand smoke as well as ambient air pollution are strikingly similar.4,6,7 They include progression of atherosclerotic plaques to vulnerable forms, prothrombotic states, endothelial dysfunction, and altered autonomic nervous system control (Figure). Increased systemic oxidative stress is considered the key mechanism responsible for most of these pathophysiological changes. Increased risks for cardiovascular disease in general and coronary artery disease in particular have been documented for active and secondhand smoke as well as ambient particulate matter. Deep venous thrombosis has been added to this list recently.8 Figure. Overview on pathomechanism linking ambient air pollution,4 secondhand smoke,7 and active smoking to acute coronary syndromes. Nevertheless, the public health relevance of particulate matter in the light of the smoking literature remains hotly debated. Smokers are exposed to considerably higher cumulative doses of particulate matter than the general nonsmoking population. Mortality due to low doses of ambient particles may be considered counterintuitive compared with doses of particles tolerated by smoking individuals. A systematic assessment of the exposure-response function ranging from low doses of inhaled particles …

Indoor and outdoor levels of respirable particulates (PM 10) and Carbon Monoxide (CO) in high-rise apartment buildings

The present study evaluated exposure to two mobile source-related pollutants (CO and PM 10) in high-rise apartment buildings, according to floor height. The outdoor air concentrations of CO and PM 10 were higher for the lower-floor apartments than for the higher-floor apartments, and they were significantly higher in the winter and summer. However, the difference of indoor concentrations between the lower-floor and higher-floor apartments depended upon the season. Most indoor and outdoor concentrations of PM 10 were significantly higher in apartments, which were in close proximity to a major roadway, as compared to those further away, whereas the indoor and outdoor concentrations of CO did not vary much according to distances from major roadways. Atmospheric stability was important regarding the level of exposure to both CO and PM 10 for residents of high-rise apartment buildings. These parameters (apartment floor, proximity to roadways, season, and atmospheric stability) should be considered when evaluating the level of exposure to CO and PM 10 for residents living in high-rise apartment buildings. The median PM 10 outdoor concentrations were close to or lower than the Korean annual standard for PM 10 (70 μg m −3) or the American annual standard (50 μg m −3). Neither the median nor the maximum outdoor CO concentrations were higher than the Korean 8-h CO standard (9 ppm). However, the maximum PM 10 concentrations substantially exceeded the Korean standard, thus suggesting the need for a management strategy regarding episodic ambient PM 10 pollution.

The open-ocean source of atmospheric carbon monoxide

Abstract Carbon monoxide (CO) atmospheric mixing ratios and surface-water concentrations were determined during Atlantic Meridional Transect cruise number 10, April–May 2000. Atmospheric CO increased from south (mean=74±9 ppbv) to north (mean=151±19 ppbv) with a steep increase around the intertropical convergence zone. Surface-water CO (0.2–2.6 nmol L −1 ) showed pronounced diurnal variations with afternoon maxima exceeding pre-dawn minima 5–7 fold. Modest regional variations, as indicated by maximum daily CO concentrations, were also observed. Highest CO maxima occurred at ∼11.5°N, where high solar irradiance was combined with elevated coloured dissolved organic matter (CDOM) levels and modest winds, while lowest CO maxima occurred during periods of high winds and lowest solar irradiance near the western European margin at 45°N. Atlantic Ocean CO emissions were estimated to be 1.5±1.1 Tg CO-C yr −1 based on near-instantaneous atmospheric CO, sea-surface CO and windspeeds from the cruise. However, as spatial and temporal variability in both terms was considered to be unique to the timing and path of the cruise, the mean Atlantic diel cycle of sea-surface CO concentration was estimated by pooling all cruise data into 1-h sections, yielding a mean of 0.94 nmol L −1 ; and diurnal variations from 0.4 to 1.6 nmol L −1 . Using the mean diurnal cycle, the Atlantic and global open-ocean sources of CO to the atmosphere were estimated to be 0.9±0.6 and 3.7±2.6 Tg CO-C yr −1 , respectively. Therefore it is our contention that IPCC-2001 (Prather, M., Ehhalt, D., Dentener, F., Derwent, R., Dlugokencky, E., Holland, E., Isaksen, I., Katima, J., Kirchhoff, V., Matson, P., Midgley, P., Wang, M., 2001. Chapter 4: Atmospheric chemistry and greenhouse gases. In: Houghton, J.T., Ding, Y., Griggs, D.J., Noguer, M., van der Linden, P.J., Dai, X., Maskell, K., Johnson, C.A. (Eds.), Climate Change 2001: The Scientific Basis. Contribution of working group 1 to the third assessment report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, pp. 239–287; 21 Tg CO-C yr −1 ) overestimates the source of atmospheric CO from the global ocean by around 5 fold.

Evaluation of Street‐Canyon Carbon Monoxide—Dispersion Simulation Model

This paper reports on the evaluation of a dispersion simulation model that predicts carbon monoxide (CO), concentrations in urban street canyons. The distribution characteristics of vehicle-generated carbon monoxide concentrations measured at six major urban arterials in Riyadh, Saudi Arabia are presented. The maximum 1-hour and 8-hour CO concentrations monitored annually over a three-year period, are shown. The structure of the composite street canyon model that was used to predict the hourly concentrations of carbon monoxide at study arterials is discussed. A comparative analysis of predicted versus measured concentrations is made. The model, although unsophisticated, predicts CO levels that agree reasonably well with the values measured in Riyadh. The model is felt to be generally applicable to the conditions of the rapidly developing urban areas of the Persian Gulf.

Updated Model Assessment of Pollution at Major U.S. Airports

The air quality impact of aircraft at and around Los Angeles International Airport (LAX) was simulated for hours of peak aircraft operation and 'worst case' pollutant dispersion conditions by using an updated version of the Argonne Airport Vicinity Air Pollution model; field programs at LAX, O'Hara, and John F. Kennedy International Airports determined the 'worst case' conditions. Maximum carbon monoxide concentrations at LAX were low relative to National Ambient Air Quality Standards; relatively high and widespread hydrocarbon concentrations indicated that aircraft emissions may aggravate oxidant problems near the airport; nitrogen oxide concentrations were close to the levels set in proposed standards. Data on typical time-in-mode for departing and arriving aircraft, the 8/4/77 diurnal variation in airport activity, and carbon monoxide concentration isopleths are given, and the update factors in the model are discussed.

Minimum protection factors for respiratory protective devices for firefighters.

Carbon monoxide and oxygen concentrations were measured in seventy-two structural fires using a personal air sampler carried by working firefighters. In a total sampling time of 1329 minutes the carbon monoxide concentration exceeded 500 ppm approximately 29 percent of the time. The maximum carbon monoxide concentration was 27,000 ppm and in 10 percent of the fires, the maximum concentration exceeded 5500 ppm. Only six runs indicated oxygen concentrations less than 18 percent. On the basis of these exposure data, a minimum protection factor of 100 is proposed for breathing apparatus for structural firefighting.