Ambient Carbon Monoxide Concentrations Research Articles

Evaluation of Ambient Air Quality Level at Various Locations within Lead City University, Ibadan

BACKGROUND: Air quality in university environment is strongly affected by the student population explosion, climatic conditions and industrial activity within the institution. Monitoring the main air pollutants such as carbon dioxides, carbon monoxide and particulate matter may help control the most polluted areas of the institution and take measures to reduce the pollution.Universities are big metropolitan institutions with sizable populations of students, employees, and visitors. However, university settings can contribute to air pollution, with diverse activities such as lab work, cooking in dorms, and vehicle traffic, among others, causing interior and ambient air pollution. It is impossible to estimate how much air pollution affects the health and happiness of students without embarking on this type of research work. PURPOSE/AIM: Evaluation of meteorology parameters (i.e. temperature and relative humidity (RH)) and ambient air quality (CO, CO2 and particulate matter (PM2.5)) level at various locations within Lead City University, Ibadan is essential. METHODOLOGY: Ambient concentrations of carbon monoxide (CO), carbon dioxide (CO2), Relative humidity (RH), Temperature (TEMP), and Particulate Matter (PM2.5) were measured in 15 locations across Lead City University over a two-week period (between 25th of June 2023 and 3rd of August 2023) with Bosean air quality detector -T-201. RESULTS: Morning temperatures in all the locations measured ranging from 23.7°C to 29.2°C while afternoon temperature fluctuates more significantly, with the lowest recorded at 27.2°C and the highest at a notably warmer 35.8°C in all the locations measured. The morning RH levels ranging from 63.8% to 74.7% while afternoon RH values, ranging from 58.2% to 63.4%. The finding also shows that afternoon CO2 levels range from 468.5 ppm to 971.6 ppm, with Location 13 having an unusually high average. Morning CO levels ranging from 4.1 ppm to 49 ppm, with location 13 showing the most highest figure of 184.2 ppm. CO2 and CO levels are mostly within acceptable ranges as recommended by World Health Organization (WHO) that CO2 concentration levels in school buildings should kept below 1000 ppm and CO be below an average of nine parts per million (ppm) for any eight-hour period, and below 25 ppm for any one-hour period as an indicative benchmark of good indoor air quality (IAQ). Morning RH values range from 63.8% to 74.7%, with Location 1 having the highest average while afternoon RH values are between 58.9% and 67.7%, with Location 6 having the highest average. The relatively narrow variance in RH indicates that the dataset predominantly represents conditions with moderate humidity levels. Morning PM levels vary from 8.9 to 17.1µg/m³, suggesting diverse air quality conditions across the samples. In the afternoon, PM concentrations display a broader range, from 8.9 to an exceptionally high 436.1 in Location 13. Interestingly, all the air pollutants measured are still within the USA EPA permissible level of the National Ambient Air Quality Standard for PM2.5, which is 35 μg/m3, and CO, which is 40 mg/m3 and CO2 between 400 - 1,000ppm CONCLUSION: Variability in these parameters has implications for human health therefore, adequate ventilation and pollution control measures is thereby recommended for the university management in order to improve indoor air quality.

Evaluation of Ambient Air Quality Levels at Various Locations within Lead City University, Ibadan

Universities are big metropolitan institutions with sizable populations of students, employees, and visitors. However, university settings can contribute to air pollution, with diverse activities such as lab work, cooking in dorms, and vehicle traffic, among others, causing interior and ambient air pollution. It is impossible to overestimate how much air pollution affects the health and happiness of students. Based on this, evaluation of ambient air quality (i.e., temperature, relative humidity (RH), CO2, and particulate matter (PM2.5)) at various locations within Lead City University, Ibadan, is essential. Ambient concentrations of carbon monoxide (CO), carbon dioxide (CO2), relative humidity (RH), temperature (TEMP), and particulate matter (PM) were recorded from 15 locations across Lead City University over a two-week period. Morning temperatures in all the locations measured ranged from 23.7°C to 29.2°C, while afternoon temperatures fluctuated more significantly, with the lowest recorded at 27.2°C and the highest at a notably warmer 35.8°C in all the locations measured. The morning RH levels ranged from 63.8% to 74.7%, while afternoon RH values ranged from 58.2% to 63.4%. The findings also show that afternoon CO2 levels range from 468.5 ppm to 971.6 ppm, with Location 13 having an unusually high average. Morning CO levels ranged from 4.1 µg/m³ to 49 µg/m³, with location 13 showing an outlier at 184.2 µg/m³. CO2 and CO levels are mostly within acceptable ranges. Conclusively, variability in these parameters has implications for human health; therefore, adequate ventilation and pollution control measures are thereby recommended for the university management in order to improve indoor air quality.

Association of ambient carbon monoxide exposure with hospitalization risk for respiratory diseases: A time series study in Ganzhou, China.

Ambient carbon monoxide (CO) exposure is associated with increased mortality and hospitalization risk for total respiratory diseases. However, evidence on the risk of hospitalization for specific respiratory diseases from ambient CO exposure is limited. Data on daily hospitalizations for respiratory diseases, air pollutants, and meteorological factors from January 2016 to December 2020 were collected in Ganzhou, China. A generalized additive model with the quasi-Poisson link and lag structures was used to estimate the associations between ambient CO concentration and hospitalizations of total respiratory diseases, asthma, chronic obstructive pulmonary disease (COPD), upper respiratory tract infection (URTI), lower respiratory tract infection (LRTI), and influenza-pneumonia. Possible confounding co-pollutants and effect modification by gender, age, and season were considered. A total of 72,430 hospitalized cases of respiratory diseases were recorded. Significant positive exposure-response relationships were observed between ambient CO exposure and hospitalization risk from respiratory diseases. For each 1 mg/m3 increase in CO concentration (lag0-2), hospitalizations for total respiratory diseases, asthma, COPD, LRTI, and influenza-pneumonia increased by 13.56 (95% CI: 6.76%, 20.79%), 17.74 (95% CI: 1.34%, 36.8%), 12.45 (95% CI: 2.91%, 22.87%), 41.25 (95% CI: 18.19%, 68.81%), and 13.5% (95% CI: 3.41%, 24.56%), respectively. In addition, the associations of ambient CO with hospitalizations for total respiratory diseases and influenza-pneumonia were stronger during the warm season, while women were more susceptible to ambient CO exposure-associated hospitalizations for asthma and LRTI (all P < 0.05). In brief, significant positive exposure-response relationships were found between ambient CO exposure and hospitalization risk for total respiratory diseases, asthma, COPD, LRTI, and influenza-pneumonia. Effect modification by season and gender was found in ambient CO exposure-associated respiratory hospitalizations.

Within-city variation in ambient carbon monoxide concentrations: Leveraging low-cost monitors in a spatiotemporal modeling framework

Exposure to ambient carbon monoxide (CO) may be associated with cardiovascular disease outcomes based on human and animal experimental evidence, but current epidemiologic research is limited. The number and distribution of ground-level regulatory agency monitors are insufficient to characterize potential fine-scale variation of CO. This study aimed to develop a high-resolution ambient CO prediction model at the daily scale based on both regulatory agency monitoring data and measurements from calibrated low-cost gas monitors in Baltimore, Maryland. We also evaluated the contribution of three novel parameters to model performance, including high-resolution meteorological data, satellite remote sensing data, and co-pollutant concentrations (PM2.5, NO2, and NOx). The CO model had spatial cross-validation (CV) R² (RMSE) of 0.70 (0.02 parts per million, ppm) and temporal CV R² (RMSE) of 0.61 (0.04 ppm). The predictions revealed spatially resolved CO hotspots associated with population, traffic, and other non-road emission sources (e.g., railroads and airport), as well as sharp concentration decreases within short distances from primary roads. The three novel parameters did not substantially improve model performance, suggesting that our spatiotemporal modeling framework based on geographic features was reliable and robust. As low-cost monitors become increasingly available, this approach to CO concentration modeling can be generalized to resource-restricted environments to facilitate comprehensive epidemiologic research.

Within-City Variation in Ambient Carbon Monoxide Concentrations: Leveraging Low-Cost Monitors in a Spatiotemporal Modeling Framework.

Background:Based on human and animal experimental studies, exposure to ambient carbon monoxide (CO) may be associated with cardiovascular disease outcomes, but epidemiological evidence of this link is limited. The number and distribution of ground-level regulatory agency monitors are insufficient to characterize fine-scale variations in CO concentrations.Objectives:To develop a daily, high-resolution ambient CO exposure prediction model at the city scale.Methods:We developed a CO prediction model in Baltimore, Maryland, based on a spatiotemporal statistical algorithm with regulatory agency monitoring data and measurements from calibrated low-cost gas monitors. We also evaluated the contribution of three novel parameters to model performance: high-resolution meteorological data, satellite remote sensing data, and copollutant (, , and ) concentrations.Results:The CO model had spatial cross-validation (CV) and root-mean-square error (RMSE) of (ppm), respectively; the model had temporal CV and RMSE of 0.61 and , respectively. The predictions revealed spatially resolved CO hot spots associated with population, traffic, and other nonroad emission sources (e.g., railroads and airport), as well as sharp concentration decreases within short distances from primary roads.Discussion:The three novel parameters did not substantially improve model performance, suggesting that, on its own, our spatiotemporal modeling framework based on geographic features was reliable and robust. As low-cost air monitors become increasingly available, this approach to CO concentration modeling can be generalized to resource-restricted environments to facilitate comprehensive epidemiological research. https://doi.org/10.1289/EHP10889

A meteorologically adjusted ensemble Kalman filter approach for inversing daily emissions: A case study in the Pearl River Delta, China

The conventional Ensemble Kalman filter (EnKF), which is now widely used to calibrate emission inventories and to improve air quality simulations, is susceptible to simulation errors of meteorological inputs, making accurate updates of high temporal-resolution emission inventories challenging. In this study, we developed a novel meteorologically adjusted inversion method (MAEInv) based on the EnKF to improve daily emission estimations. The new method combines sensitivity analysis and bias correction to alleviate the inversion biases caused by errors of meteorological inputs. For demonstration, we used the MAEInv to inverse daily carbon monoxide (CO) emissions in the Pearl River Delta (PRD) region, China. In the case study, 60% of the total CO simulation biases were associated with sensitive meteorological inputs, which would lead to the overestimation of daily variations of posterior emissions. Using the new inversion method, daily variations of emissions shrank dramatically, with the percentage change decreased by 30%. Also, the total amount of posterior CO emissions estimated by the MAEInv decreased by 14%, indicating that posterior CO emissions might be overestimated using the conventional EnKF. Model evaluations using independent observations revealed that daily CO emissions estimated by MAEInv better reproduce the magnitude and temporal patterns of ambient CO concentration, with a higher correlation coefficient (R, +37.0%) and lower normalized mean bias (NMB, -17.9%). Since errors of meteorological inputs are major sources of simulation biases for both low-reactive and reactive pollutants, the MAEInv is also applicable to improve the daily emission inversions of reactive pollutants.

Monitoring of ambient carbon monoxide concentrations based on wavelength modulation direct absorption spectroscopy

Wavelength modulation-direct absorption spectroscopy (WM-DAS) has the advantages of both direct absorption spectroscopy (DAS) measurable absorptivity function and wavelength modulation spectrum (WMS) with high signal-to-noise ratio (SNR). In this paper, the WM-DAS spectrum is used to measure the absorptivity of 4300.7 cm&lt;sup&gt;–1&lt;/sup&gt; line of CO molecule and the detection limit is as low as 4 × 10&lt;sup&gt;–7&lt;/sup&gt; (200 s) at 0.5 m optical path, room temperature and low pressure. Then, through combining the WM-DAS spectrum with a 120 m long optical path Herriott cell, at room temperature and atmospheric pressure, the standard deviation of the fitting residual error of the absorptivity function is reduced down to ~5.1 × 10&lt;sup&gt;–5&lt;/sup&gt; (1 s). Finally, different concentrations of CO are continuously monitored by long-path WM-DAS measurement system, and compared with the results obtained from the cavity ring-down spectroscopy (CRDS). The experimental results show that the measurement results from the long-path WM-DAS and CRDS method are the same. The detection limit of CO concentration in long-path WM-DAS system is as low as 0.9 ppb (200 s), and the WM-DAS system is simple and the measurement speed is much faster than CRDS. At the same time, the long-path WM-DAS system is used to continuously monitor the atmospheric trace CO concentration and trend for one month, and the measured results are highly consistent with those from the China Environmental Monitoring Station.

Wildfires and wood stoves: Woodsmoke toxicity and chemical characterization study in the north-western United States

PM2.5 is the most monitored air pollutant for which EPA has set national ambient air quality standards (NAAQS). As such, it is the pollutant on which the Air Quality Index (AQI) is most often based. PM2.5 and PM10 are the only criteria pollutant whose composition, and therefore toxicity varies. The PM2.5 AQI does not account for chemical composition. In areas where woodsmoke is the dominant PM2.5 source, coemitted hazardous air pollutants (HAPs) could impact community health differently than indicated by PM2.5 based AQI. PM2.5, carbon monoxide (CO), and particle light absorption were measured continuously from August 2018 through May 2019 in a suburban community where woodsmoke contributed the majority of ambient PM2.5. Air samples were also collected at least every 6 days at the site and analyzed for a suite of hazardous air pollutants (HAPs). EPA's positive matrix factorization (PMF) model 5.0 was used to identify the primary source contributors to local air pollution and apportion what fraction of each pollutant was from woodsmoke. Both measurements and the PMF model result showed significant chemical distinction between wood stove and wildfire smoke. Wildfire smoke contained significantly less CO and organic compounds than wood stove smoke relative to measured PM2.5. Comparing select HAPs to ambient CO concentration indicated atmospheric oxidation depleted PAHs in the wildfire smoke, although the relative amount of UV absorbing organic carbon did not change. HAPs most strongly associated with wood combustion were assessed relative to their individual cancerous and non-cancerous screening levels, as well as the PM2.5 and CO NAAQS.

Monitoring of ambient carbon monoxide concentrations based on wavelength modulation direct absorption spectroscopy

波长调制-直接吸收光谱（WM-DAS）同时具有直接吸收光谱（DAS）可测量吸收率函数和波长调制光谱（WMS）高信噪比的优点，本文首先采用WM-DAS光谱，在50 cm光程和室温低压下，CO分子近红外4300.7 cm-1谱线吸收率检测限低至4×10-7（200 s）；然后结合120 m长光程Herriott池，在室温大气压下，吸收率函数拟合残差标准差达到5.1×10-5（1 s）。最后利用长光程WM-DAS测量系统，对不同浓度（0.44~9.6 ppm）CO进行了动态测量，并将其与腔衰荡光谱（CRDS）进行比较；实验结果表明：本文采用的长光程WM-DAS与CRDS方法测量结果相同，其中长光程WM-DAS系统CO浓度检测限低至0.9 ppb（200 s），系统简单且测量速度远快于CRDS。与此同时，利用建立的长光程WM-DAS测量系统连续监测1个月时间内大气痕量CO浓度及其变化趋势，其测量结果与中国环境监测总站高度一致。

Region-specific air pollutants and meteorological parameters influence COVID-19: A study from mainland China

Coronavirus disease 2019 (COVID-19) was first detected in December 2019 in Wuhan, China, with 11,669,259 positive cases and 539,906 deaths globally as of July 8, 2020. The objective of the present study was to determine whether meteorological parameters and air quality affect the transmission of COVID-19, analogous to SARS. We captured data from 29 provinces, including numbers of COVID-19 cases, meteorological parameters, air quality and population flow data, between Jan 21, 2020 and Apr 3, 2020. To evaluate the transmissibility of COVID-19, the basic reproductive ratio (R0) was calculated with the maximum likelihood “removal” method, which is based on chain-binomial model, and the association between COVID-19 and air pollutants or meteorological parameters was estimated by correlation analyses. The mean estimated value of R0 was 1.79 ± 0.31 in 29 provinces, ranging from 1.08 to 2.45. The correlation between R0 and the mean relative humidity was positive, with coefficient of 0.370. In provinces with high flow, indicators such as carbon monoxide (CO) and 24-h average concentration of carbon monoxide (CO_24 h) were positively correlated with R0, while nitrogen dioxide (NO2), 24-h average concentration of nitrogen dioxide (NO2_24 h) and daily maximum temperature were inversely correlated to R0, with coefficients of 0.644, 0.661, −0.636, −0.657, −0.645, respectively. In provinces with medium flow, only the weather factors were correlated with R0, including mean/maximum/minimum air pressure and mean wind speed, with coefficients of −0.697, −0.697, −0.697 and −0.841, respectively. There was no correlation with R0 and meteorological parameters or air pollutants in provinces with low flow. Our findings suggest that higher ambient CO concentration is a risk factor for increased transmissibility of the novel coronavirus, while higher temperature and air pressure, and efficient ventilation reduce its transmissibility. The effect of meteorological parameters and air pollutants varies in different regions, and requires that these issues be considered in future modeling disease transmissibility.

Short-term exposure to carbon monoxide and myocardial infarction: A systematic review and meta-analysis

BackgroundPrevious studies suggest an association between short-term exposure to carbon monoxide and myocardial infarction. We performed a systematic review and meta-analysis to assess current evidence on this association to support the update of the World Health Organization (WHO) Global Air Quality Guidelines. MethodsWe searched Medline, Embase and Cochrane Central Register of Controlled Trials to update the evidence published in a previous systematic review up to 30th September 2018 for studies investigating the association between short-term exposure to ambient carbon monoxide (up to lag of seven days) and emergency department visits or hospital admissions and mortality due to myocardial infarction. Two reviewers assessed potentially eligible studies and performed data extraction independently. Random-effects meta-analysis was used to derive the pooled risk estimate per 1 mg/m3 increase in ambient carbon monoxide concentration. Risk of bias in individual studies was assessed using a domain-based assessment tool. The overall certainty of the body of evidence was evaluated using an adapted certainty of evidence assessment framework. ResultsWe evaluated 1,038 articles from the previous review and our updated literature search, of which, 26 satisfied our inclusion criteria. Overall, myocardial infarction was associated with exposure to ambient carbon monoxide concentration (risk ratio of 1.052, 95% confidence interval 1.017–1.089 per 1 mg/m3 increase). A third of studies were assessed to be at high risk of bias (RoB) due to inadequate adjustment for confounding. Using an adaptation of the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework, the overall evidence was assessed to be of moderate certainty. ConclusionsThis review demonstrated that the pooled risk ratio for myocardial infarction was 1.052 (95% CI 1.017–1.089) per 1 mg/m3 increase in ambient carbon monoxide concentration. However, very few studies originated from low- and middle-income countries.

Ambient air pollution and markers of fetal growth: A retrospective population-based cohort study of 2.57 million term singleton births in China

BackgroundsEvidence is scarce on the relation between maternal exposure to ambient air pollution during pregnancy and fetal growth in developing countries. Moreover, the current evidence is inconsistent. We aimed to investigate the association of trimester-specific exposure to air pollution with risk of being born small for gestational age (SGA) and birth weight-markers of fetal growth-among Chinese term births. MethodsThis retrospective population-based cohort study consisted of 2,567,457 singleton term live-births from January 1, 2014 to December 31, 2017 across 123 Chinese districts and counties. Personal exposure to ambient air pollutants including carbon monoxide (CO), sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), particulate matter with aerodynamic diameter < 2.5 μm (PM2.5), and PM10 was assigned using the inverse distance weighting spatial interpolation algorithm. Generalized estimating equations (GEE) logistic regression models were performed to estimate the associations between trimester-specific exposure to air pollution and risk of SGA or low birth weight (LBW), and GEE linear regression to examine the associations between the exposure and term birth weight, adjusting for maternal demographics, maternal cigarette smoking status during pregnancy, mode of delivery, gravidity, gestational age, year and month of conception, neonate’s sex, and meteorological factors. Stratified and sensitivity analyses were also performed. ResultsWhen mother exposed to ambient air pollutants over the entire pregnancy, per IQR increment (0.122 mg/m3) in ambient CO concentrations was associated with higher risk of SGA (odds ratio (OR) = 1.04, 95% confidence interval (CI): 1.02, 1.05) and reduced birth weight among term births (−5.95 g, 95% CI: −8.01, −3.89). This association was also pronounced in the second and third trimesters. Term birth weight was negatively associated with per IQR increase of O3 (−3.52 g, 95% CI: −6.23, −0.81), PM2.5 (−5.93 g, 95% CI: −8.36, −3.49) and PM10 (−7.78 g, 95% CI: −10.41, −5.16) during the entire pregnancy, respectively. No significant association was detected between maternal exposure to air pollutants and term LBW. Effect estimates of heterogeneity suggested that maternal age and infant sex modified the impact of air pollution on birth weight. ConclusionsThe findings suggest that maternal exposure to air pollution during pregnancy is adversely affecting fetal growth. Further studies are warranted to integrate these findings and take clinical or public health interventions in pregnancy.

Estimating cardiovascular hospitalizations and associated expenses attributable to ambient carbon monoxide in Lanzhou, China: Scientific evidence for policy making

ObjectivesAir pollution is an important trigger of cardiovascular disease worldwide, but few studies have determined the cardiovascular disease, health, and economic burdens attributable to ambient carbon monoxide (CO). This study aimed to examine the association between CO and CVD hospitalizations, and quantified the attributable CVD hospitalizations, associated hospital stays and hospitalization costs for CO in Lanzhou, one of the most air-polluted Chinese cities historically. MethodsDaily data on CVD hospitalizations, air pollutants, and weather records from 2013 to 2017 were obtained for Lanzhou, China. Generalized additive model with a quasi-Poisson link was used to model the association between CO and CVD hospitalizations, after controlling for other air pollutants, weather conditions, day of week, long-term trend, influenza and pneumonia incidence. The effects of CO on hospital stays and hospitalization expenses from CVD were also quantified. ResultsCO concentrations below the current Chinese ambient air quality standard had a significant impact on CVD hospitalizations. Each 1 mg/m3 increase in CO concentration on the present day and previous 4 days (lag 0–4) was associated with an 11% (95% confidence interval: 3%–20%) increase in total CVD hospitalizations. During the study period, CO was responsible for 11.74% of total CVD hospitalizations, equating to 62,792 inpatient days and 149 million RMB. Each adult patient on average spent approximately 5% of annual salary on medicine from CO-related CVD treatment during hospitalization. Maintaining the historical CO concentration within 1 to 3 mg/m3 could avert hundreds of total CVD hospitalizations and save millions of RMB annually in Lanzhou, China. ConclusionsExposure to low-level ambient CO concentration increased the risk of CVD hospitalizations and resulted in substantial health and economic burdens in Lanzhou, China. Our findings can be used for evidence-based practice and policy making to assess the cost-effectiveness of prevention measures.

Ambient carbon monoxide and increased risk of daily hospital outpatient visits for respiratory diseases in Dongguan, China

BackgroundThe toxicity of high-concentration carbon monoxide (CO) on human health has previously been documented. However, the epidemiological evidence on the association between acute exposure to ambient CO and respiratory diseases is relatively lacking and controversial. ObjectivesTo examine the short-term association between ambient CO and hospital outpatient visits for respiratory diseases in Dongguan, China. MethodsThe number of daily hospital outpatient visits for respiratory diseases, and air pollution and meteorological data were collected from January 2013 to August 2017. A generalized additive model with a quasi-Poisson link was used to estimate the association between ambient CO concentration and the total number of hospital outpatient visits for all respiratory diseases and those for asthma, bronchiectasis, chronic obstructive pulmonary disease (COPD) and pneumonia. We further analyzed the effect of ambient CO by gender and age. ResultsOver the study period, a 24-h mean concentration of ambient CO of 0.88 mg/m3 (below the limit for CO in China) and a total of 89,484 hospital outpatient visits for respiratory diseases were recorded. Ambient CO was found to increase the risk for asthma, bronchiectasis, pneumonia and the total number of respiratory diseases. The per interquartile range (IQR) increase in ambient CO at lag03 day corresponded to a 5.62% (95% confidence interval (CI): 3.24%, 8.05%), 8.86% (95% CI: 4.89%, 12.98%), 6.67% (95% CI: 0.87%, 12.81%) and 7.20% (95% CI: 2.35%, 12.29%) increased risk in outpatient visits for all respiratory diseases, asthma, bronchiectasis and pneumonia, respectively. Each association was partially weakened after adjusting for co-pollutants. The effect of ambient CO on respiratory diseases appeared to be greater for females and the elderly. ConclusionsShort-term exposure to ambient CO was associated with increased risk of outpatient visits for respiratory diseases. Our analysis may help to understand the health effects of low-levels of CO and provide evidence for the creation of air quality standards.

Association between ambient air pollution and pregnancy rate in women who underwent IVF.

Are the concentrations of five criteria air pollutants associated with probabilities of biochemical pregnancy loss and intrauterine pregnancy in women? Increased concentrations of ambient particulate matter (PM10), nitrogen dioxide (NO2), carbon monoxide (CO) during controlled ovarian stimulation (COS) and after embryo transfer were associated with a decreased probability of intrauterine pregnancy. Exposure to high ambient air pollution was suggested to be associated with low fertility and high early pregnancy loss in women. Using a retrospective cohort study design, we analysed 6621 cycles of 4581 patients who underwent one or more fresh IVF cycles at a fertility centre from January 2006 to December 2014, and lived in Seoul at the time of IVF treatment. To estimate patients' individual exposure to air pollution, we computed averages of hourly concentrations of five air pollutants including PM10, NO2, CO, sulphur dioxide (SO2) and ozone (O3) measured at 40 regulatory monitoring sites in Seoul for each of the four exposure periods: period 1 (start of COS to oocyte retrieval), period 2 (oocyte retrieval to embryo transfer), period 3 (embryo transfer to hCG test), and period 4 (start of COS to hCG test). Hazard ratios (HRs) from the time-varying Cox-proportional hazards model were used to estimate probabilities of biochemical pregnancy loss and intrauterine pregnancy for an interquartile range (IQR) increase in each air pollutant concentration during each period, after adjusting for individual characteristics. We tested the robustness of the result using generalised linear mixed model, accounting for within-woman correlation. Mean age of the women was 35 years. Average BMI was 20.9 kg/m2 and the study population underwent 1.4 IVF cycles on average. Cumulative pregnancy rate in multiple IVF cycles was 51.3% per person. Survival analysis showed that air pollution during periods 1 and 3 was generally associated with IVF outcomes. Increased NO2 (adjusted HR = 0.93, 95% CI: 0.87, 0.99) and CO (0.94, 95% CI: 0.89, 1.00) during period 1 were associated with decreased probability of intrauterine pregnancy. PM10 (0.92, 95% CI: 0.85, 0.99), NO2 (0.93, 95% CI = 0.86, 1.00) and CO (0.93, 95% CI: 0.87, 1.00) levels during period 3 were also inversely associated with intrauterine pregnancy. Both PM10 (1.17, 95% CI: 1.04 1.33) and NO2 (1.18, 95% CI: 1.03, 1.34) during period 3 showed positive associations with biochemical pregnancy loss. The district-specific ambient air pollution treated as an individual exposure may not represent the actual level of each woman's exposure to air pollution. Smoking, working status, parity or gravidity of women, and semen analysis data were not included in the analysis. This study provided evidence of an association between increased ambient concentrations of PM10, NO2 and CO and reduced probabilities for achieving intrauterine pregnancy using multiple IVF cycle data. Specifically, our results indicated that lower intrauterine pregnancy rates in IVF cycles may be linked to ambient air pollution during COS and the post-transfer period. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2013 R1A6A3A04059017, 2016 R1D1A1B03933410 and 2018 R1A2B6004608) and the National Cancer Center of Korea (NCC-1810220-01). The authors report no conflicts of interest. N/A.

Temporal Variations in Ambient Carbon Monoxide Concentrations between Weekdays and Weekends in Akure Central Business District, South West Nigeria

Temporal Variations in Ambient Carbon Monoxide Concentrations between Weekdays and Weekends in Akure Central Business District, South West Nigeria

Driving restrictions that work? Quito's Pico y Placa Program

AbstractPrograms to reduce traffic congestion and air pollution by restricting use of motor vehicles on working days have generally not met with success, given existing studies of such programs. We conduct the first study of Quito, Ecuador's four‐year‐old Pico y Placa program and find that it has reduced ambient concentrations of carbon monoxide (CO), a pollutant primarily emitted by vehicles, by 9% to 11% during peak traffic hours. Given that ambient concentrations of CO generally track the spatial and temporal distributions of traffic, these reductions in pollution suggest similar reductions in vehicle flows. We find no significant evidence that traffic has shifted to other times of the day or week, or to other locations.

Carbon Monoxide Poisonings from Forklift Use During Produce Packing Operations

ABSTRACTIn August 2013, the North Carolina Division of Public Health investigated a carbon monoxide (CO) exposure on a farm. Two employees were overcome by CO and lost consciousness while using a propane-powered forklift to load produce into a refrigerated trailer backed up to a warehouse. One employee died, and the second employee was admitted to the hospital for hyperbaric oxygen treatment. Eighteen people, ranging in age from 18 to 69 years, were potentially exposed to CO, including the two employees, a family member who discovered the employees, two bystanders who stopped to offer assistance, and 13 first responders. Thirteen people who assisted in the emergency response experienced symptoms such as headache and dizziness, and all 16 who assisted were evaluated in a local hospital emergency department and released after receiving 100% oxygen. Blood tests showed five people (the two employees, family member, and two bystanders) had elevated blood carboxyhemoglobin levels, but all first responders had levels within normal range. Firefighters measured a peak CO concentration of 2214 parts per million in the warehouse. The North Carolina Division of Occupational Safety and Health investigated and determined that the forklift, operated inside the trailer with no ventilation, was the source of the CO. Public health investigation activities included interviewing responders, obtaining ambient CO concentration measurements from the fire department, advising the local health director, reviewing medical records, and developing a line listing of exposed persons. To prevent CO poisoning, employers should consider replacing gas-powered equipment with electric equipment, which does not produce CO.

Carbon monoxide and stroke: A time series study of ambient air pollution and emergency hospitalizations

BackgroundRecent experimental and clinical studies suggested that exogenous carbon monoxide (CO) at low concentrations may have beneficial neuroprotective effects under certain circumstances. However, population-based epidemiological studies of environmentally relevant CO exposure generated mixed findings. The present study aimed to examine the short-term association of ambient CO with emergency stroke hospitalizations. MethodsA time series study was conducted. Daily air pollution concentrations and emergency hospital admission data from January 2004 to December 2011 in Hong Kong were collected. Generalized additive Poisson models were used to estimate the associations between daily 24-hour mean concentrations of CO and emergency hospital admissions for stroke, while controlling for other traffic related co-pollutants: NO2 and PM2.5. Sensitivity analyses were performed using daily 1-hour maximum concentration of CO as exposure indicator. ResultsNegative associations were observed between ambient CO concentrations and emergency hospital admissions for stroke. The previous 1–3day cumulative exposure to CO was associated with a −2.0% (95%CI, −3.3% to −0.7%) decrease in stroke admissions per interquartile range (IQR) increment in CO concentration (0.3ppm). Similar results were obtained when using 1-hour maximum concentration of CO as exposure indicator. The negative association was robust to the co-pollutant adjustment for either NO2 or PM2.5. Females and elders appeared to be more sensitive to ambient CO exposure. The negative association tended to be larger in cool season. ConclusionShort-term exposure to ambient CO was associated with decreased risk of emergency hospitalizations for stroke, suggesting some acute protective effects of CO exposure against stroke onsets.

Does ambient CO have protective effect for COPD patient?

BackgroundExisting studies found paradoxical effects of carbon monoxide (CO) on human health. Carbon monoxide (CO), at high concentrations, is a well-known toxicant, but recent studies suggest that CO at low concentrations may have protective health effects under certain conditions. ObjectivesTo investigate the acute effect of ambient CO on hospital admission for chronic obstructive pulmonary disease (COPD) in Shanghai, China. MethodsDaily data on COPD admissions and CO concentrations between 2006 and 2008 were collected. We applied over-dispersed generalized additive Poisson models, adjusted for weather conditions, day of the week and public holidays, long-term and seasonal trends. ResultsDuring the study period, the average CO concentration was 1.3mg/m3, well below the international health-based standard. Negative associations were found between ambient CO concentration and daily COPD hospitalization. An interquartile range increase (0.6mg/m3) in CO concentration at lag 3day corresponded to −2.97% (95% confidence interval: −4.63%, −1.31%) change in COPD hospitalization. The negative associations were robust after adjustment for co-pollutants (PM10, NO2 and SO2). The protective effect of CO appeared to be more evident in the cool season. ConclusionShort-term exposure to CO at low ambient concentration may be associated with reduced risk of COPD hospitalization. Our results may contribute to a comprehensive understanding on the health effects of ambient CO.