Concentration Of Carbon Monoxide In Air Research Articles

Systematic review and meta-analysis investigating nicotine, cotinine and carbon monoxide exposures in people who both smoke and use nicotine replacement therapy.

To determine effects of concurrent smoking and nicotine replacement therapy (NRT) use on reported heaviness of smoking, nicotine (cotinine) body fluid and exhaled air carbon monoxide (CO) concentrations. Systematic review and meta-analysis of RCTs, which test interventions permitting concurrent NRT use and smoking and comparing, within participants, outcomes when smoking with those when smoking and using NRT concurrently. Measurements included reported number of cigarettes smoked per day (CPD), body fluid cotinine and expired air CO concentrations. Twenty-nine studies were included in the review. Meta-analysis of nine showed that, compared with when solely smoking, fewer cigarettes were smoked daily when NRT was used (mean difference during concurrent smoking and NRT use, -2.06 CPD [95% CI = -3.06 to -1.07, P < 0.0001]). Meta-analysis of seven studies revealed a non-significant reduction in exhaled CO during concurrent smoking and NRT use (mean difference, -0.58 ppm [95% CI = -2.18 to 1.03, P = 0.48]), but in the three studies that tested NRT used in the lead-up to quitting (i.e. as preloading), a similar reduction in exhaled CO was statistically significant (mean difference, -2.54 ppm CO [95% CI = -4.14 to -0.95, P = 0.002]). Eleven studies reported cotinine concentrations, but meta-analysis was not possible because of data reporting heterogeneity; of these, seven reported lower cotinine concentrations with concurrent NRT use and smoking, four reported no differences, and none reported higher concentrations. People who smoke and also use nicotine replacement therapy report smoking less heavily than people who solely smoke. When nicotine replacement therapy is used in the lead-up to quitting (preloading), this reported smoking reduction has been biochemically confirmed. There is no evidence that concurrent smoking and nicotine replacement therapy use result in greater nicotine exposure than solely smoking.

Synthesis and characterization of Sm2O3 nanorods for application as a novel CO gas sensor

Sm2O3 nanorods have been successfully synthesized by a simple hydrothermal process in the presence of cetyl trimethyl ammonium bromide (CTAB) as an organic template. The morphological, microstructural and optical characteristics of the synthesized nanorods were investigated by scanning electron microscopy (SEM-EDX), X-ray diffraction analysis (XRD), micro-Raman spectroscopy and photoluminescence (PL). The complementary investigations substantiated the purity of the material synthesized, constituted of Sm2O3 nanorods in the single cubic crystalline phase having a mean length of about 400 nm and diameter of about 80 nm.A conductometric sensor based on the synthesized Sm2O3 nanorods has been developed. The sensor performances were investigated in the detection of carbon monoxide (CO) in air. At the optimal operating temperature of 250 °C, the sensor showed a response S = Rg/Ra = 1.4 toward 5 ppm of CO, a limit of detection (LOD) of 1 ppm at signal-to-noise ratio S/N = 3, fast response/recovery time (35 s and 110 s, respectively) and selectivity against the most common air pollutant gases. The results demonstrated that the developed sensor based on Sm2O3 nanorods has superior performances in the monitoring of low concentration of CO in air compared to the state of the art rare-earth oxide CO sensors.

Short-Term Prediction of Carbon Monoxide Concentration Using Artificial Neural Network (NARX) Without Traffic Data: Case Study: Shiraz City

Air pollution is one of the most widespread and important issues in mechanical civilization, and it has made supervision and control of air quality an ineluctable issue that has been introduced as a principal national problem. This study investigates the ability of dynamic neural networks, particularly the nonlinear autoregressive exogenous (NARX) network, in predicting air carbon monoxide concentration in Shiraz in the absence of traffic data since there are no accurate statistical data on traffic volume (as one of the primary sources for air pollution modeling). Dynamic networks have been utilized to model time-variable patterns as they have time memory through the history of concentration volume implicitly containing traffic characteristics. To begin this study, meteorological data including temperature, moisture content, rainfall amount, and wind velocity and direction at a 3-h mean basis were obtained from the Bureau of Meteorology at the Shiraz Airport. Moreover, air pollutant concentration data due to Setad Square’s measurement station between 2005 and 2008 were prepared from the Fars Department of Environmental Protection. According to the results obtained from the static neural network, the correlation coefficients (R) for the training, validation, and test datasets are estimated as 0.49, 0.37, and 0.41, respectively. Moreover, the R2 correlation coefficient, the root mean square error (RMSE), and mean absolute percentage error (MAPE) are 0.31, 0.43, and 51%, respectively. However, the correlation coefficients achieved from NARX model for the training, validation, and test datasets are estimated as 0.77, 0.76, and 0.80, respectively, while the R2 correlation coefficient, RMSE, and MAPE are 0.72, 0.05, and 7%, respectively. The results demonstrate the dynamic neural network’s high performance in modeling carbon monoxide concentration in the absence of traffic data. Moreover, sensitivity analysis indicates the stability of the model to the noisy data.

АДСОРБЦІЙНО-НАПІВПРОВІДНИКОВИЙ СЕНСОР МОНООКСИДУ ВУГЛЕЦЮ, СТВОРЕНИЙ НА ОСНОВІ НАНОРОЗМІРНОГО МАТЕРІАЛУ Pt/SnO2

Nanosized material SnO2 was obtained by a sol-gel technique to create a sensor purposed for determination of carbon monoxide concentration in air. Platinum was added to the nanosized tin dioxide by a wet impregnation method using H2PtCl6 solution. According to TEM data the average size of the SnO2 particles in the obtained nanosized tin dioxide was equal to 10–11 nm. Sensor nanomaterials based on SnO2 and Pt/SnO2 powders which were sintered at 620°C in air atmosphere consisted of spheric particles with average sizes 20 and 14–15 nm, correspondingly. Phase compositions of the obtained nanomaterials were studied by the XRD method. Only a phase of cassiterite was detected for the nanomaterials with and without platinum. The absence of any reflexes of platinum-containing phases in the diffraction pattern of Pt/SnO2 is most likely due to the low content of platinum in the material. It was shown that dopping the nanosized SnO2 materials by platinum lead to increase their catalytic activities in the reaction of CO oxidation: the temperature of practically complete conversion of CO using Pt/SnO2 catalyst was equal to 110°С. The sensor created on the base of Pt/SnO2 nanomaterial was found to be more sensitive to CO than the one created without platinum in the range of its heater power consumption 0.25–0.45 W. High catalytic activity of the Pt/SnO2 nanomaterial in the reaction of CO oxidation is a reason of such sensor sensitivity increase. The dependence of the sensitivity of the sensor on the heater power consumption has a maximum that can be explained by the change of the amount of oxygen chemisorbed on the sensor gas sensitive layer when the sensor temperature is increased. The maximal sensor sensitivity to CO is γ = 10 at the optimal heater power consumption of the sensor (0.3 W). The created sensor to CO based on the nanomaterial Pt/SnO2 was found to be very fast. The response time of the sensor (τ0,9) was equal to 4,5 sec and the relax time (τrelax) was equal to 9.8 sec. It was shown that the created sensor based on nanomaterial Pt/SnO2 has high sensitivity to carbon monoxide and possess good dynamic properties, which makes the sensor to be promising for usage it in gas analytical devices purposed for determination of CO in air.

Effects of Prenatal Tobacco and Wood-Fuel Smoke Exposure on Birth Weight in Sri Lanka.

Low birth weight is a key public health problem in many developing countries, including Sri Lanka. Indoor air pollution from tobacco smoke and kitchen-fuel smoke are among the major contributors to low birth weight, factors of which there are little awareness of in Sri Lanka. We evaluated the effect of passive smoking and kitchen-fuel smoke exposure on birth weight. Seventy-six pregnant women were included in the study. Data were collected by questionnaire, and exposure assessment was conducted using a breath carbon monoxide monitor. Women exposed to second-hand tobacco smoke daily had a significantly lower mean gestational age at delivery (mean ± standard error [SE]: 38.0 ± 0.5 weeks) than women who were exposed to second-hand tobacco smoke only once a week (mean ± SE: 39.3 ± 0.3 weeks) (p < 0.05). Women who were exposed to tobacco smoke every day delivered neonates with significantly lower mean birth weight (mean ± SE: 2703 ± 135 g) than women who were only exposed once a week (mean ± SE: 3125 ± 147 g) (p < 0.05). A one-minute increase in cooking time in a kitchen without a chimney increased women’s expired air carbon monoxide concentration by 0.038 ppm (p = 0.006). Long-term exposure to wood-fuel smoke in a kitchen without a chimney can increase the risk of inhaling high concentrations of carbon monoxide.

Indoor Air Quality and its Health Impacts in Thame, Sagarmath National Park, Nepal

In many developing world, respiratory problems such as chronic obstructive pulmonary disease (COPD) has been of major concern and is attributed to the indoor air pollution. The aim of this study was to monitor the indoor air quality and assess its health impact on 104 subjects of 35 households of Thame Village Development Committee, Solukhumbu District. It was carried out for nine days in November 2008. In the Kitchen, emission of Carbon monoxide (CO) and Particulate matter (PM) in the size range ≤ 2.5 μm (PM2.5) were monitored as an indicator of indoor air pollution. The instruments used were UCB particulate monitor and HOBO CO meter. Similarly, Spirometer was used to assess the respiratory function. PM2.5, concentration varied between 0.4mg/m3 and 10mg/m3. Maximum concentration of about 10 mg/m3 was observed for traditional cooking stove (TCS) with no chimneys. For the modern or improved cooking stoves ICS) with ventilation from pipes and chimneys, the concentrations were below 0.4mg/m3. Similarly, the average indoor air CO concentration for 8 hours has been found to be between 5 and 30 ppm, depending on different stove types. The highest concentration of about 200 ppm was observed at the time of cooking (ca. 2 hours average) using TCS with chimney only. In addition, health spirometry test was performed on 70 subjects of Thame Village Development Committee (VDC) and 34 subjects of different villages and background. The spirometry test indicated that ca. 14% of the subjects showed mild obstruction whereas ca. 5% showed moderate obstruction. It has to be noted that despite the recent switch to the alternative cleaner energy source from the polluting solid fuels, the long term exposure in the past might show its adverse effect in the old ages.

Group Waterpipe Tobacco Smoking Increases Smoke Toxicant Concentration

Waterpipe tobacco smoking is a global health concern. Laboratory research has focused on individual waterpipe users while group use is common. This study examined user toxicant exposure and smoke toxicant yield associated with individual and group waterpipe smoking. Twenty-two pairs of waterpipe smokers used a waterpipe individually and as a dyad. Before and after smoking, blood was sampled and expired carbon monoxide (CO) measured; puff topography was recorded throughout. One participant from each pair was selected randomly and their plasma nicotine and expired air CO concentrations were compared when smoking alone to when smoking as part of a dyad. Recorded puff topography was used to machine-produce smoke that was analyzed for toxicant content. There was no difference in mean plasma nicotine concentration when an individual smoked as part of a dyad (mean = 14.9 ng/ml; standard error of the mean [SEM] = 3.0) compared to when smoking alone (mean = 10.0 ng/ml; SEM = 1.5). An individual smoking as part of as a dyad had, on average, lower CO (mean = 15.8 ppm; SEM = 2.0) compared to when smoking alone (mean= 21.3 ppm; SEM = 2.7). When two participants smoked as a dyad they took, on average, more puffs (mean = 109.8; SEM = 7.6) than a singleton smoker (mean = 77.7; SEM = 8.1) and a shorter interpuff interval (IPI; dyad mean = 23.8 seconds; SEM = 1.9; singleton mean = 40.8 seconds; SEM = 4.8). Higher concentrations of several toxicants were observed in dyad-produced smoke. Dyad smoking may increase smoke toxicant content, likely due to the dyad's shorter IPIs and greater puff number. More work is needed to understand if group waterpipe smoking alters the health risks of waterpipe tobacco smoking. This study is the first to measure toxicants in smoke generated from a waterpipe when used by a dyad. Relative to smoke generated by a singleton, dyad smoke had higher concentration of some toxicants. These differences may be attributed to differences in puffing behavior, specifically the shorter IPI and greater puff number observed in the dyad condition. Relative to singleton smokers, dyad smokers were exposed to less CO, but nicotine exposure did not differ. More work is needed to assess the health effects of inhalation of more toxicant-laden smoke during group waterpipe use.

Could Smokers’ Socio-Demographic and Housing Factors Affect and Influence the Choice Between Smoking Cessation Therapies?

Introduction: The published data suggest that interventions which combine pharmacotherapy and behavioural support increase success rates of smoking cessation compared to minimal intervention or usual care; however, a standardized behavioural psychotherapy programme has not been assessed yet. Our main aim was to assess if socio-demographic and housing characteristics of smokers attending an Italian smoking cessation centre, could have influenced the choice between varenicline therapy and psychological support only. Our secondary aims were: i) to evaluate the 6-month abstinence rates (ARs), confirmed by comparing exhaled air carbon monoxide concentrations, in smokers according to whether they took varenicline or received only psychological support; ii) to assess the most frequently reported adverse drug reactions (ADRs) by the varenicline group, mainly focusing on psychiatric events; iii) to evaluate the differences between men and women with regard to specific varenicline-related ADRs Method: 142 smokers were enrolled; all of them received the same psychological support programme. They were evaluated by a team of clinical experts, who advised them to opt for either one quitting method or the other; then the smokers chose themselves a treatment option of either varenicline plus psychotherapy (VAR: 78 patients) or psychotherapy alone (PSY: 64 patients). Results: Socio-demographic and psychological characteristics of patients have significantly influenced the treatment choice; the 6-month ARs were 35.9% versus 10.9% (p<0.01) in those using varenicline versus psychotherapy, respectively; 57.7% of the patients reported at least one adverse event. Conclusion: The analysis of socio-demographic factors and psychological characteristics of patients seems to be necessary to offer them the most effective therapy in order to achieve good abstinence rates. Therefore, this study confirms the data about the efficacy and safety of varenicline. Our screening methods and exclusion criteria seem to be valid aids to achieving good therapeutic outcomes with a low risk of occurrence of severe psychiatric events.

Fifty-two-week continuous abstinence rates of smokers being treated with varenicline versus nicotine replacement therapy

Cross-study comparisons of effect sizes suggest that varenicline is more effective than nicotine replacement therapy (NRT) in aiding smoking cessation, but evidence from direct comparisons is limited. This study compared biochemically verified 52-week sustained abstinence rates in smokers attending the same clinical service according to whether they used varenicline or NRT in their quit attempt. This was a prospective cohort study of 855 smokers attending a large smoking cessation clinic who used their choice of NRT product or varenicline in their quit attempt. All received the same behavioural support programme and chose their medication option (n = 519 varenicline; n = 336 NRT). The primary outcome measure was self-report of 52 weeks' abstinence following the target quit date confirmed by expired air carbon monoxide concentration. Baseline measures included socio-demographic variables, mental health diagnoses, measures of smoking, cigarette dependence and past use of NRT or varenicline. The 52-week abstinence rates were 42.8% versus 31.0% in those using varenicline versus NRT, respectively (P < 0.001). After adjusting for all baseline variables, the odds of remaining abstinent for 52 weeks were 2.03 (95% CI 1.46-2.82), P < 0.001 times higher in those using varenicline than those using NRT. Smokers in the same behavioural support programme who use varenicline appear to have a greater probability of achieving long-term abstinence than those using their choice of nicotine replacement therapy options, even after adjusting for potentially confounding smoker characteristics.

Lectin-Like Oxidized Low-Density Lipoprotein Receptor-1 Plays an Important Role in Vascular Inflammation in Current Smokers

Smoking induces vascular inflammation and increases the risk of cardiovascular events. Lectinlike oxidized low-density lipoprotein receptor-1 (LOX-1) is a scavenger receptor that is induced by oxidative stress and is associated with atherosclerotic plaque formation and destabilization. LOX-1 interacts with C-reactive protein (CRP) and plays an important role in inflammatory diseases. We therefore hypothesized that LOX-1 may be involved in the onset of smoking-induced vascular inflammation. We measured the soluble LOX-1 (sLOX-1) levels in sera obtained from 207 current smokers. The serum sLOX-1 levels positively correlated with various smoking variables, such as the number of cigarettes smoked per day (r= 0.150, p<0.05), the expired air carbon monoxide (CO) concentrations (r= 0.198, p<0.005) and the Fagerstrom test for nicotine dependence scores (r= 0.190, p<0.01). The serum levels of sLOX-1 also correlated with those of a representative inflammatory marker, the serum high-sensitivity CRP level (hsCRP; r= 0.232, p<0.005). A multivariate regression analysis revealed the independent determinants of the serum sLOX-1 level to be the expired air CO concentration (β= 0.182, p<0.05) and the hsCRP level (β= 0.213, p<0.01). The serum sLOX-1 level was found to increase in close association with both the smoking-related variables and the inflammatory marker hsCRP. These findings suggest that LOX-1 may therefore play an important role in the onset of smoking-induced inflammation and atherosclerosis in humans.

A prospective 12-month study of the effect of smoking cessation on periodontal clinical parameters

The aim of this 12-month prospective study was to assess the adjunctive effect of smoking cessation in non-surgical periodontal therapy of subjects with severe chronic periodontitis. Of the 201 subjects enrolled from a smoking cessation clinic, 93 were eligible and received non-surgical periodontal treatment and concurrent smoking cessation treatment. Periodontal maintenance was performed every 3 months. Full-mouth periodontal examination in six sites per tooth was performed by a calibrated examiner, blinded to smoking status, at baseline, 3, 6 and 12 months after non-surgical periodontal treatment. Furthermore, expired air carbon monoxide concentration measurements and interviews based on a structured questionnaire were performed in order to collect demographic and smoking data. Of the 93 eligible subjects, 52 remained in the study after 1 year. Of these, 17 quit smoking and 35 continued smoking or oscillated. After 1 year, only quitters presented significant clinical attachment gain (p=0.04). However, there were no differences between the groups regarding clinical attachment level, probing depth, bleeding on probing and plaque index after 1 year (p>0.05). Smoking cessation promoted clinical attachment gain in chronic periodontitis subjects from a smoking cessation clinic after 1 year of follow-up.

Effectiveness of a stepped primary care smoking cessation intervention (ISTAPS study): design of a cluster randomised trial

BackgroundThere is a considerable body of evidence on the effectiveness of specific interventions in individuals who wish to quit smoking. However, there are no large-scale studies testing the whole range of interventions currently recommended for helping people to give up smoking; specifically those interventions that include motivational interviews for individuals who are not interested in quitting smoking in the immediate to short term. Furthermore, many of the published studies were undertaken in specialized units or by a small group of motivated primary care centres.The objective of the study is to evaluate the effectiveness of a stepped smoking cessation intervention based on a trans-theoretical model of change, applied to an extensive group of Primary Care Centres (PCC).Methods/DesignCluster randomised clinical trial. Unit of randomization: basic unit of care consisting of a family physician and a nurse, both of whom care for the same population (aprox. 2000 people). Intention to treat analysis.Study population: Smokers (n = 3024) aged 14 to 75 years consulting for any reason to PCC and who provided written informed consent to participate in the trial.Intervention: 6-month implementation of recommendations of a Clinical Practice Guideline which includes brief motivational interviews for smokers at the precontemplation – contemplation stage, brief intervention for smokers in preparation-action who do not want help, intensive intervention with pharmacotherapy for smokers in preparation-action who want help, and reinforcing intervention in the maintenance stage.Control group: usual care.Outcome measures: Self-reported abstinence confirmed by exhaled air carbon monoxide concentration of ≤ 10 parts per million. Points of assessment: end of intervention period and 1 and 2 years post-intervention; continuous abstinence rate for 1 year; change in smoking cessation stage; health status measured by SF-36.DiscussionThe application of a stepped intervention based on the stages of a change model is possible under real and diverse clinical practice conditions, and improves the smoking cessation success rate in smokers, besides of their intention or not to give up smoking at baseline.Trial RegistrationClinical Trials.gov Identifier: NCT00125905

The combination of a smoking cessation programme with rehabilitation increases stop-smoking rate

A parallel group study to investigate the effectiveness of a smoking cessation programme performed during routine rehabilitation practice for outpatients. The study participants comprised an intervention group of 102 consecutive smokers who underwent a smoking cessation programme in a rehabilitation centre and a control group of 101 consecutive smokers who were referred to a smoking cessation centre in a pulmonary hospital. All participants underwent physical examination,pulmonary function tests and received identical behavioural and/or pharmacological treatment. In addition, the intervention group underwent rehabilitation practice 3 times a week for 3 months. The continuous abstinence rate at 12 months, which was validated by an expired air carbon monoxide concentration of 10 parts per million or less and a household interview, was 68% in the intervention group and 32% in the control group. Multivariable analysis showed that rehabilitation was significantly associated with smoking cessation after adjusting for years of smoking, number of cigarettes smoked,gender and treatment (odds ratio = 4.34, p < 0.001). This study suggests that smoking cessation programmes during routine rehabilitation may be highly effective in helping smoking withdrawal and should be a strongly recommended component of rehabilitation practice.

Contaminación por monóxido de carbono: un problema de salud ambiental

Carbon monoxide is considered to be a major factor contaminating earth's atmosphere. The main sources producing this contamination are cars using gasoline or diesel fuel and industrial processes using carbon compounds; these two are responsible for 80% of carbon monoxide being emitted to the atmosphere. This substance has a well-known toxic effect on human beings and its acute poisonous effects (including death) have been widely studied; however, its long-term chronic effects are still not known. During the last few years, experimental research on animals and studies of human epidemiology have established the relationship between chronic exposure to low and middle levels of carbon monoxide in breathable air and adverse effects on human health, especially on organs consuming large amounts of oxygen such as the heart and brain. Harmful cardiovascular and neuropsychological effects have been documented in carbon monoxide concentration in air of less than 25 ppm and in carboxyhaemoglobin levels in blood of less than 10%. The main cardiac damage described to date has been high blood pressure, cardiac arrhythm and electrocardiograph signs of ischemia. Lack of memory, attention, concentration and Parkinson-type altered movement are the neuropsychological changes most frequently associated with chronic exposure to low levels of carbon monoxide and carboxyhaemoglobin.

A randomized trial assessing the Five-Day Plan for smoking cessation

To evaluate the effectiveness of the Five-Day Plan (FDP) in helping smokers to stop smoking. Randomized controlled trial comparing intervention and control groups. The primary outcome measure was 12 months continuous abstinence verified by expired air carbon monoxide concentration. Secondary outcome measures were self-reported abstinence at end of treatment, at 3 and 6 months. Six towns in France. 228 smokers, recruited by newspaper and radio advertisement, aged 18 years or over and willing to make an attempt to quit smoking. The Intervention group (119 participants) received the FDP, which is a behavioural group-based treatment programme that has been in operation in France since 1965. It involves five consecutive evening behavioural therapy sessions. The Control group (109 participants) received a single session discussing the health effects of smoking. In the Intervention group, 67 participants (56%) quit smoking at the end of the FDP. After three months this number had been reduced to 30 (25%) and to 19 (16%) by the end of one year. In the Control group these numbers were 14 (13%) and 12 (11%), respectively, after three and 12 months. When considering the rate of cessation without lapse after one year a significant difference was observed with a 13% rate in the Intervention group and 3% in the Control group (P = 0.004). The FDP may be considered as an aid for smokers who want to quit.

Exposure to carbon monoxide during indoor karting

Karting is a recreational activity of increasing popularity and it is often practiced indoors leading to build up of toxic gases in ambient air. This study was realised to verify the level of exposure to carbon monoxide (CO) in ten male racers (Age: 15 to 49 years old) during a 45-min race. The alveolar concentration of CO (alvCO) for each participant was measured before and after the race. The ambient CO level was determined continuously from the start to the end of the race with two detectors. Mean ambient air CO concentration was 41 ppm and the average increase of alvCO for the ten subjects was 16.2 ppm corresponding to about 3% COHb. Based on these results and on the Coburn model, a reference limit of 25 ppm was suggested for a 1 h exposure during indoor karting. At the request of the public health authorities, some modifications were made to the karts, to the CO monitoring surveillance system and to the ventilation system of the building. CO concentrations were monitored thereafter. The guideline of 25 ppm for 60 min was always respected.

Expired air carbon monoxide concentration in mothers and their spouses above 5 ppm is associated with decreased fetal growth

Background. Smoking during pregnancy is associated with reduced birthweight; this relation can be reversed by smoking cessation. Some but not all previous studies have shown that smoking reduction (measured as cigarettes/day or urinary cotinine) may also improve birthweight. The relationship between maternal and spouses' expired air carbon monoxide (CO) concentrations (EACO) on fetal growth has not yet been evaluated. Methods. Eight hundred fifty-six smoking and nonsmoking pregnant women were followed during their pregnancy. Their EACO was determined in the first trimester and during delivery. The spouses' EACO were also measured at delivery. The main outcome measure was the infants' birthweight. Secondary measures included head circumference, Apgar score, and heart rate at delivery. Cord blood fetal carboxyhemoglobin (FCOHb) served as internal control. Results. Birthweight dose-dependently and significantly decreased with increasing level of maternal (0–5: 3406 ± 32; 6–10: 3048 ± 57; 11–20: 2858 ± 54; >20 ppm: 2739 ± 34 g, P < 0.0001) or spouses' EACO (0–5: 3546 ±25; 6–10: 3484 ± 51; 11–20: 3309 ± 47; >20 ppm: 3190 ± 57 g, P < 0.0001). Even the birthweight of newborns whose mother had EACO between 6 and 10 ppm was significantly lower than the birthweight of newborns whose mother had an EACO between 0 and 5 ppm. Spouses' EACO of delivering women with EACO of 0–5 ppm showed similar effect. Head circumference, Apgar score, and normal term gestational age decreased also significantly with increasing maternal or spouses' EACO. Conclusions. Both maternal and spouses' EACO measured during delivery, a proxy of EACO during pregnancy, were dose-dependently and inversely associated with fetal growth. Even low maternal (6 to 10 ppm) or spouses' (11 to 20 ppm) EACO may be associated with significantly lower birthweight.

Evaluation of exposure to carbon monoxide associated with passive smoking

The current study measured breath carbon monoxide (CO) concentrations prior to and at prescribed time intervals after exposure to passive smoking under controlled conditions, along with the air CO concentration in the exposure room during the exposure periods. The postexposure breath CO levels were 1.4–2.7 times higher than the background breath CO levels after 30 min of exposure, yet only slightly higher after 10 min of exposure, thereby confirming that exposure to CO from passive smoking causes a significant body burden of CO. The air CO concentration gradually increased during the burning of a cigarette(s), regardless of the exposure duration, whereas it slightly decreased after burning. However, the pattern of breath CO decay was similar for the two different types of exposure (during and after a cigarette(s)) in each subject. The decrease in the postexposure alveolar CO concentrations was slow even in the early phase of the decay curves, indicating a monocompartment uptake and elimination model for the human body. The half-lives (78–277 min) estimated in the present study were comparable to those reported in previous studies associated with CO exposure from active smoking or other activities. The current study also evaluated the CO exposure of visitors and workers at three different types of recreation facility (bars, Internet cafes, and billiard halls) typically associated with passive smoking. The results confirmed that passive smoking is the major contributor to the CO exposure of nonsmoking visitors in a recreation environment. In addition, workplace exposure to CO from passive smoking was found to be the most important contributor to the daily CO exposure of nonsmoking recreation workers.

Personal carbon monoxide exposures of preschool children in Helsinki, Finland—comparison to ambient air concentrations

The associations of personal carbon monoxide (CO) exposures with ambient air CO concentrations measured at fixed monitoring sites, were studied among 194 children aged 3–6 yr in four downtown and four suburban day-care centers in Helsinki, Finland. Each child carried a personal CO exposure monitor between 1 and 4 times for a time period of between 20 and 24 h. CO concentrations at two fixed monitoring sites were measured simultaneously. The CO concentrations measured at the fixed monitoring sites were usually lower (mean maximum 8-h concentration: 0.9 and 2.6 mg m −3) than the personal CO exposure concentrations (mean maximum 8-h concentration: 3.3 mg m −3). The fixed site CO concentrations were poor predictors of the personal CO exposure concentrations. However, the correlations between the personal CO exposure and the fixed monitoring site CO concentrations increased (−0.03–−0.12 to 0.13–0.16) with increasing averaging times from 1 to 8 h. Also, the fixed monitoring site CO concentrations explained the mean daily or weekly personal CO exposures of a group of simultaneously measured children better than individual exposure CO concentrations. This study suggests that the short-term CO personal exposure of children cannot be meaningfully assessed using fixed monitoring sites.

Carboxyhemoglobin and brain blood flow in humans

It has been shown that with increased carboxyhemoglobin (COHb) and associated decrease in blood oxygen-carrying capacity, a compensatory increase in brain-blood flow (BBF) develops. The BBF response in humans has been shown to be quite variable. Two experiments were conducted in which humans were exposed to sufficient carbon monoxide (CO) to produce COHb levels up to 18.4%. BBF was measured by the method of impedance plethysmography. The first was a pilot study in which BBF in 14 men was studied after transient exposure to various concentrations of CO in air. BBF increased as a function of COHb but not to the same extent (or at all) in some subjects. In a confirmatory experiment with 12 men, BBF was measured once per h during a 4-h experiment. All 12 subjects received CO. The variation of the BBF response among subjects was large and statistically significant whereas the variation over time was not significant. Thus it appears that the magnitude of the BBF response is unique for a given subject and differs across subjects. These results may help predict CO-induced behavioral decrements in future studies if subjects whose BBF response to COHb is small or absent are also more susceptible to impairment by acute CO exposure.