Carbon Monoxide Concentrations Research Articles

Physiological basis for atmospheric methane oxidation and methanotrophic growth on air.

Atmospheric methane oxidizing bacteria (atmMOB) constitute the sole biological sink for atmospheric methane. Still, the physiological basis allowing atmMOB to grow on air is not well understood. Here we assess the ability and strategies of seven methanotrophic species to grow with air as sole energy, carbon, and nitrogen source. Four species, including three outside the canonical atmMOB group USCα, enduringly oxidized atmospheric methane, carbon monoxide, and hydrogen during 12 months of growth on air. These four species exhibited distinct substrate preferences implying the existence of multiple metabolic strategies to grow on air. The estimated energy yields of the atmMOB were substantially lower than previously assumed necessary for cellular maintenance in atmMOB and other aerobic microorganisms. Moreover, the atmMOB also covered their nitrogen requirements from air. During growth on air, the atmMOB decreased investments in biosynthesis while increasing investments in trace gas oxidation. Furthermore, we confirm that a high apparent specific affinity for methane is a key characteristic of atmMOB. Our work shows that atmMOB grow on the trace concentrations of methane, carbon monoxide, and hydrogen present in air and outlines the metabolic strategies that enable atmMOB to mitigate greenhouse gases.

Measurement of the vertical distributions of atmospheric pollutants using an uncrewed aerial vehicle platform in Xi'an, China.

Vertical observations of atmospheric pollutants play crucial roles in a comprehensive understanding of the distribution characteristics and transport of atmospheric pollutants. A hexacopter uncrewed aerial vehicle equipped with miniature monitors was employed to measure the vertical distribution of atmospheric pollutants within a height of 1000 m at a rural site in Xi'an, China, in 2021. The concentrations of carbon monoxide (CO) and particulate matter (PM) showed generally decreasing trends with increasing height. The ozone (O3) concentration showed a general increasing trend with height followed by a gradual decreasing trend. Vertical decrements of PM2.5 and CO from 0 to 1000 m were significantly (p < 0.05) lower on observation days during summer (14.0 ± 8.1 μg m-3 and 8.7 ± 6.6 ppb, respectively), compared with those in winter (78.3 ± 14.1 μg m-3 and 34.8 ± 17.3 ppb, respectively). The horizontal transport of PM and CO mostly occurred in the morning and at night during winter observations at an altitude of 400-500 m. During the winter haze, the PM and CO profile concentrations below 500 m increased substantially with the decrease in the height of the thermal inversion layer. Vertical O3 transportation was observed in the afternoon and evening during summer, and a ∼37.7% (11.6 ppb) increase in ground-level O3 was observed in relation to vertical transport from the upper atmosphere. The results provide insights into the vertical distribution and transport of atmospheric pollutants in rural areas near cities.

Relationship Between Air Pollutants and the Incidence of Epistaxis in Yangzhou.

Objectives: This project aims to explore the relationship between the air quality index (AQI), the concentration of 6 air pollutants, and the incidence of epistaxis in Yangzhou. Also, to provide reference information for the prevention and treatment of epistaxis. Methods: Data of patients with epistaxis admitted to the Northern Jiangsu People's Hospital Affiliated to Yangzhou University from January 2017 to December 2021 were collected. In addition, the local AQI and the concentrations of 6 air pollutants, namely particulate matter (PM2.5, PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3), were analyzed at the time of onset. Furthermore, the correlation with the incidence of epistaxis has been analyzed. Results: From 2017 to 2021, there were 24,721 patients with epistaxis aged from 0 to 17 years old while male patients were more than females. The incidence was higher in April, May, and June. There was a statistically significant difference in the number of daily epistaxis in different months and under AQI conditions (P < .05). Spearman's correlation analysis showed that there was a positive correlation between the number of daily epistaxis and the concentrations of AQI, CO, NO2, O3, PM2.5, PM10, and SO2 in Yangzhou, in which O3, PM10, and SO2 were highly correlated with the average number of daily epistaxis, and there was no obvious time lag effect of air pollutants on epistaxis. Conclusion: Epistaxis in the Yangzhou area is more common in males, mostly occurs in 0 to 17 years old, with seasonal. There was also a positive correlation between the incidence of epistaxis and air pollutants in Yangzhou. Therefore, by reducing the AQI index in daily life, and reducing the concentration of environmental pollutants in the air, the occurrence of epistaxis could be prevented and reduced to a certain extent.

Energy-efficient scientific-technological approaches to the processing of plastic waste PET, PE, PP, PS to produce hydrogen-containing gas and titanium carbide powder

The paper considers gaseous products, structure and phase composition of hard products resulting from high-temperature exothermic reactions between Ti–PET–(PE, PP, PS) system components, depending on the content of oxygen-free polymers polyethylene (PE), polypropylene (PP), and polystyrene (PS) in the initial blend. It is found that the addition of PE, PP, PS polymers to the Ti–PET system increases the hydrogen content from 45 to 62 vol% and reduces the carbon monoxide content from 38 to 20 vol% in gaseous products. According to calculations, the adiabatic flame temperature of the synthesized gas in air is very close to that of pure hydrogen. The synthesized gas can therefore be used as ecological fuel for energy sources. On the other hand, oxygen-free polymers presenting in the system provide the formation of substoichiometric carbide TiC0.75. Its hardness is not lower than that of stoichiometric TiC and even exceeds widely used carbides and borides of transition metals. In addition, the agglomerate structure of synthesized TiC0.75 allows to apply it as a promising ecological basis for highly-efficient abrasive pastes, in particular for polishing and finishing fabricated metal products.

Beneficial Effects of Oral Carbon Monoxide on Doxorubicin-Induced Cardiotoxicity.

Doxorubicin and other anthracyclines are crucial cancer treatment drugs. However, they are associated with significant cardiotoxicity, severely affecting patient care and limiting dosage and usage. Previous studies have shown that low carbon monoxide (CO) concentrations protect against doxorubicin toxicity. However, traditional methods of CO delivery pose complex challenges for daily administration, such as dosing and toxicity. To address these challenges, we developed a novel oral liquid drug product containing CO (HBI-002) that can be easily self-administered by patients with cancer undergoing doxorubicin treatment, resulting in CO being delivered through the upper gastrointestinal tract. HBI-002 was tested in a murine model of doxorubicin cardiotoxicity in the presence and absence of lung or breast cancer. The mice received HBI-002 twice daily before doxorubicin administration and experienced increased carboxyhemoglobin levels from a baseline of ≈1% to 7%. Heart tissue from mice treated with HBI-002 had a 6.3-fold increase in CO concentrations and higher expression of the cytoprotective enzyme heme oxygenase-1 compared with placebo control. In both acute and chronic doxorubicin toxicity scenarios, HBI-002 protected the heart from cardiotoxic effects, including limiting tissue damage and cardiac dysfunction and improving survival. In addition, HBI-002 did not compromise the efficacy of doxorubicin in reducing tumor volume, but rather enhanced the sensitivity of breast 4T1 cancer cells to doxorubicin while simultaneously protecting cardiac function. These findings strongly support using HBI-002 as a cardioprotective agent that maintains the therapeutic benefits of doxorubicin cancer treatment while mitigating cardiac damage.

Highly dispersed Pt nanoparticles onto dendritic silicas as colorimetric probe for CO sensing in mainstream cigarette smokes

Carbon monoxide (CO) is a typical substance harmful to human body produced during cigarette smoking. Its content in cigarette smoke is one of the important indicators for evaluating its toxicity and the filtration effect of cigarette filter tips, which provides important guidance for its rational design. In this work, Pt nanoparticles with superior peroxidase catalytic ability were synthesized and loaded onto fibrous SiO2 nanoparticles as nanozymes to detect CO in cigarette smoke by taking advantage of the reduced catalytic performance of CO adsorption on the active sites of the nanozymes. The fibrous SiO2 not only provide abundant sites for the deposition and dispersion of Pt NPs, but also prevent their aggregation and thus maintain their high catalytic activity. Density functional theory calculations reveal that Pt nanoparticles exhibits superior peroxidase ability over Au and Pd nanoparticles, which can be significantly inhibited by CO. Accordingly, a nanozyme-inhibition based colorimetric method was developed for the detection of CO in cigarette smoke with the limit of detection of 0.15 mg/L. The applicability of this method was validated by analyzing the CO contents in 8 kinds of cigarette smoke with different types of filter tips. The concentrations of CO are in the range of 5.40 to 6.73 mg/branch, which are in good agreement with those of GC results, indicating the accuracy and reliability of our method. This assay is fast, convenient and sensitive for quantitatively assessing the CO content in cigarette smoke, and it lays the foundation for prompting the widespread use of nanozyme-inhibition in chemical sensing.

Isolation and identification of carbon monoxide producing microorganisms from compost

Carbon monoxide (CO) formation has been observed during composting of various fractions of organic waste. It was reported that this production can be biotic, associated with the activity of microorganisms. However, there are no sources considering the microbial communities producing CO production in compost. This preliminary research aimed to isolate and identify microorganisms potentially responsible for the CO production in compost collected from two areas of the biowaste pile: with low (118 ppm) and high CO concentration (785 ppm). Study proved that all isolates were bacterial strains with the majority of rod-shaped Gram-positive bacteria. Both places can be inhabited by the same bacterial strains, e.g. Bacillus licheniformis and Paenibacillus lactis. The most common were Bacillus (B. licheniformis, B. haynesii, B. paralicheniformis, and B. thermolactis). After incubation of isolates in sealed bioreactors for 4 days, the highest CO levels in the headspace were recorded for B. paralicheniformis (>1000 ppm), B. licheniformis (>800 ppm), and G. thermodenitrificans (∼600 ppm). High CO concentrations were accompanied by low O2 (<6%) and high CO2 levels (>8%). It is recommended to analyze the expression of the gene encoding CODH to confirm or exclude the ability of the identified strains to convert CO2 to CO.

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.

Postmortem concentrations for total blood carbon monoxide (TBCO) as novel biomarker for carbon monoxide (CO) poisonings.

Total Blood Carbon Monoxide (TBCO) showed promising results in improving accuracy of CO determinations in blood and presenting better stability to different storage conditions. Therefore, it was proposed as alternative biomarker to carboxyhemoglobin (COHb) for CO poisoning diagnosis. However, given that current interpretation reference values exist for COHb only, it is difficult to implement TBCO analysis in routine. Therefore, we aimed at determining TBCO reference values for postmortem CO poisoning cases. A previously validated method for TBCO analysis via gas chromatography-mass spectrometry was applied to cardiac, peripheral, cranial and spleen blood samples collected from 92 autopsies. Autopsy cases included 21 non-CO related and 71 CO-related cases with varying postmortem intervals (PMI). Statistical analyses were performed using statistical software R Studio. When comparing lower to higher PMI for non-CO related cases, no significant differences were found, which suggests that CO formation or degradation at low PMIs does not occur. Spleen blood showed potential as alternative matrix for CO determinations in cases with sample availability issues, but needs to be evaluated for CO positive cases. Results for cardiac blood in CO-related autopsies showed a positive correlation between COHb and TBCO values (R = 0.78). This value is lower than what is found in the literature, suggesting that even though COHb and TBCO are correlated, a potential underestimation of the true CO exposure might occur if only COHb values are taken into consideration. Samples were divided into CO exposure groups based on COHb concentrations and with the data obtained, classification into following TBCO concentration groups are proposed: no significant CO exposure case <6 µmol/mL, medium CO exposure case 6-20 µmol/mL, high CO exposure case >20µmol/mL. Even if a higher number of samples in each group would enable to increase the confidence, these results are very promising and highlight the importance of TBCO measurement.

Optimal planning and designing of microgrid systems with hybrid renewable energy technologies for sustainable environment in cities.

Although hybrid wind-biomass-battery-solar energy systems have enormous potential to power future cities sustainably, there are still difficulties involved in their optimal planning and designing that prevent their widespread adoption. This article aims to develop an optimal sizing of microgrids by incorporating renewable energy (RE) technologies for improving cost efficiency and sustainability in urban areas. Diverse RE technologies such as photovoltaic (PV) systems, biomass, batteries, wind turbines, and converters are considered for system configuration to obtain this goal. Net present cost (NPC) is this study's objective function for optimal sizing microgrid configuration. For demonstration, we assess the technical, economic factors, and atmospheric emissions of optimal hybrid renewable energy systems for Putrajaya City in Malaysia. The required solar radiation data, temperature, and wind speeds are collected from the NASA surface metrological database. From the quantitative analysis of simulations, the biomass-battery-based system has optimal economic outcomes compared to other systems with an NPC of around 1.07M$, while the cost of energy (COE) is 0.118 $/kWh. Moreover, environmentally safe nitrogen oxide emissions, carbon monoxide, and carbon dioxide concentrations exist. The grid-tied RE technology boasts cost-effectiveness, with an NPC of 348,318 $ and a COE of 0.0112 $/kWh. This study aids decision-makers in formulating policies for integrating hybrid RE systems in urban areas, promoting sustainable energy generation.

End-tidal carbon monoxide concentrations measured within 48 hours of birth predict hemolytic hyperbilirubinemia

End-tidal carbon monoxide concentrations measured within 48 hours of birth predict hemolytic hyperbilirubinemia

Seasonal Variations Assessment of Air Pollutants of Communities in the Vicinity of Scrap Metal Recycling Industries in Ogijo, Shagamu South LGA, Ogun State, SW Nigeria

This manuscript presents a thorough investigation into the seasonal variations of air pollutants in communities surrounding scrap metal recycling industries in Ogijo, Shagamu South LGA, Ogun State, Nigeria utilizing advanced Gary Wolf Environmental Sensing and Particulate Counting devices. The study meticulously measures concentrations of carbon monoxide, nitrogen dioxide, sulfur dioxide, PM2.5, and PM10 during both dry and wet seasons across 20 strategic sampling locations and control. The findings reveal significant seasonal fluctuations in pollutant levels, with some concentrations exceeding Nigerian ambient air quality standards, highlighting a pressing environmental health concern. The study not only underscores the critical need for regulatory oversight and the implementation of safer metal scrapping practices but also advocates for regular environmental monitoring to mitigate the adverse impacts of such industries on local communities and the environment.

Multiscale CO Budget Estimates Across South America: Quantifying Local Sources and Long Range Transport

AbstractSouth America is a large continent situated mostly in the Southern Hemisphere (SH) with complex topography and diverse emissions sources. However, the atmospheric chemistry of this region has been historically understudied. Here, we employ the Multi‐Scale Infrastructure for Chemistry and Aerosols, a novel global circulation model with regional refinement capabilities and full chemistry, to explore the sources and distribution of the carbon monoxide (CO) tropospheric column in South America during 2019, and also to assess the effect that South American primary emissions have over the rest of the world. Most of the CO over South America can be explained either by non‐methane volatile organic compounds (NMVOC) secondary chemical production or by biomass burning emissions, with biomass burning as the main explanation for the variability in CO. Biomass burning in Central Africa is a relevant contributor to CO in all of the continent, including the southern tip. Biogenic emissions play a dual role in CO concentrations: they provide volatile organic compounds that contribute to the secondary CO production, but they also destroy OH, which limits the chemical production and destruction of CO. As a net effect, the lifetime of CO is extended to ∼120 days on average over the Amazon, while still being in the range of 30–60 days in the rest of South America.

Enhanced atmospheric oxidation toward carbon neutrality reduces methane’s climate forcing

The hydroxyl radical (OH), as the central atmospheric oxidant, controls the removal rates of methane, a powerful greenhouse gas. It is being suggested that OH levels would decrease with reductions of nitrogen oxides and ozone levels by climate polices, but this remains unsettled. Here, we show that driven by the carbon neutrality pledge, the global-mean OH concentration, derived from multiple chemistry-climate model simulations, is projected to be significantly increasing with a trend of 0.071‒0.16% per year during 2015–2100. The leading cause of this OH enhancement is dramatic decreases in carbon monoxide and methane concentrations, which together reduce OH sinks. The OH increase shortens methane’s lifetime by 0.19‒1.1 years across models and subsequently diminishes methane’s radiative forcing. If following a largely unmitigated scenario, the global OH exhibits a significant decrease that would exacerbate methane’s radiative forcing. Thus, we highlight that targeted emission abatement strategies for sustained oxidation capacity can benefit climate change mitigation in the Anthropocene.

Hygienic aspects of mortality of the population of an industrial city

Introduction. The target indicators of the Federal Project “Clean Air” include a reduction in emissions of chemical pollutants by at least 20%. However, the main socially significant goal remains to improve the medical and demographic situation by reducing environmental and hygienic health risks.&#x0D; The purpose of the study was to preliminary assess the reserves for reducing mortality in the city of Omsk by identifying the most unfavourable territories in terms &#x0D; of atmospheric air quality and identify priority chemicals, presumably causing negative trend in mortality.&#x0D; Materials and methods. To assess the quality of atmospheric air in the city of Omsk, the results of social and hygienic monitoring, environmental monitoring &#x0D; of Federal Service of Russia on Hydrometeorology and Monitoring of the Environment (RosGidromet) for the multi-year period over 2009–2022 were used. &#x0D; An analysis of the mortality rate of the population of Omsk for 2017–2022 was carried out. The data were studied in the context of municipal districts of the city of Omsk and in dynamics. Statistical methods were used in the study: ANOVA, correlation analysis, assessment of relative mortality risks. &#x0D; Results. The relative risk (RR) of mortality for persons living in the most polluted areas of the city is 23–25% higher than in conditionally clean areas. Strong positive associations have been established: between the levels of actual total mortality and the specific gravity of atmospheric air samples exceeding the maximum single limit concentrations (R = 0.86; p &lt; 0.05); between perennial average annual carbon monoxide concentrations and standardized rates of total mortality &#x0D; (R = 0.93; p&lt;0.05) and male mortality rates from all natural causes (R = 0.89; p&lt;0.05).&#x0D; Limitations. The study is limited to the statistical research methods used. &#x0D; Conclusion. The results of the study can become the basis for more efficient use of administrative resources in municipal districts of the city. As additional reserves for reducing mortality, the development of primary prevention measures at the outpatient level is important. It is necessary to optimize methodological approaches in the health control system of the population living in risk areas with developed industry.

Air pollution and diabetes mellitus: Association and validation in a desert area in China.

Despite the growing evidence pointing to the detrimental effects of air pollution on diabetes mellitus (DM), the relationship remains poorly explored, especially in desert-adjacent areas characterized by high aridity and pollution. We conducted a cross-sectional study with health examination data from over 2.9 million adults in two regions situated in the southern part of the Taklamakan Desert, China. We assessed three-year average concentrations (2018-2020) of particulate matter (PM1, PM2.5, and PM10), carbon monoxide (CO), nitrogen dioxide (NO2), and sulfur dioxide (SO2) through a space-time extra-trees model. After adjusting for various covariates, we employed generalized linear mixed models to evaluate the association between exposure to air pollutants and DM. The odds ratios for DM associated with a 10 µg/m3 increase in PM1, PM2.5, PM10, CO, and NO2 were 1.898 (95% CI: 1.741, 2.070), 1.07 (95% CI: 1.053, 1.086), 1.013 (95% CI: 1.008, 1.018), 1.009 (95% CI: 1.007, 1.011), and 1.337 (95% CI: 1.234, 1.449), respectively. Notably, men, individuals aged ≥50 years, those with lower educational attainment, nonsmokers, and those not engaging in physical exercise displayed more susceptible to the adverse effects of air pollution. Multiple sensitivity analyses confirmed the stability of these findings. Our study provides robust evidence of a correlation between prolonged exposure to air pollution and the prevalence of DM among individuals living in the desert-adjacent areas. This research contributes to the expanding knowledge on the relationship between air pollution exposure and DM prevalence in desert-adjacent areas.

Machine learning predictions for carbon monoxide levels in urban environments

The increasing carbon emissions in Malaysia necessitate accurate methods to track and control pollution levels. This study focuses on predicting carbon monoxide (CO) concentrations in Petaling Jaya using various machine learning models, and two important parameters, CO concentration and time, were considered in the analysis. Six distinct machine learning models were assessed to gauge their predictive capabilities. These models encompassed a range of regression modeling techniques namely; Linear, Tree, Gaussian Process, Ensemble of Trees, Support Vector, and Artificial Neural Networks (ANN) modelling. The Matern 5/2 Gaussian Process Regression (GPR) model consistently outperformed other models across all scenarios, demonstrating high R2 values and low RMSE, MSE, and MAE values. Specifically, in scenarios 1, 2, 3, and 4, the Matern 5/2 model exhibited the lowest RMSE (0.084–0.088) and highest R2 (0.97), highlighting its reliability and robustness in predicting CO concentrations. Additionally, the Rational Quadratic model achieved an R2 of 0.97 with an RMSE of 0.088 in scenario 1, while the Quadratic SVM excelled in scenario 3 with an R2 of 0.965 and low RMSE, MSE, and MAE values (0.085, 0.007, and 0.066). These findings provide valuable insights for environmental protection, renewable energy transition, energy efficiency, sustainable land use planning, and public awareness. However, acknowledging the study's single-area focus and potential limitations in representing diverse regions, further research is warranted to explore carbon emissions across varied areas and enhance the generalizability of the findings.

Development and Performance Evaluation of Biomass-Based Injera Baking Gasifier Stove: A Case Study of Clean Cooking Technologies in Ethiopia.

The primary energy source in Ethiopia is biomass. Over 80% of Ethiopians are rural dwellers who rely on biomass energy for lighting and cooking. In most parts of Ethiopia, injera is traditionally baked using an open fire, a three stone, or a device using woody biomass. These baking stoves have very low efficiency and consume a significant amount of fuel. Moreover, these traditional baking stoves have released large amounts of indoor air pollution, which has led to different types of health-related risks, especially for women and children in the country. Therefore, the aim of this study was to investigate efficient and fuel-saving injera baking technologies. Rigorously, an injera baking gasifier stove was designed, developed, and characterized in detail through water boiling and control cooking test methods. The indoor air pollution level was evaluated using particulate matter measuring instruments. The result indicated that the developed gasifier stove had a thermal efficiency of 21.8%. Furthermore, an 86% fuel savings performance was demonstrated by the controlled cooking test for the injera baking gasifier stove. The average emission concentrations of particulate matter and carbon monoxide were 608 µg/m3 and 9 ppm, respectively, during indoor air pollution determination. The study showed that injera baking gasifier stoves are a promising cooking technology for societies where baking is mostly dependent on traditional biomass fuel.

Application of Satellite Observation and GIS in Mapping Greenhouse Gases in Part Delta State, Nigeria

The present study aimed to apply satellite observation and Geographic Information System (GIS) to map GHGs in Delta State, Nigeria. Carbon monoxide (CO), nitrous oxide (N O), and sulfur dioxide (SO ) constituted the main GHGs studied. The2 2 datasets covering January 2019 to December 2022 were sourced from the archive of Copernicus Atmosphere Monitoring Service Emissions of Atmospheric Compound and Compilation of Ancillary Data. The Google Earth Engine framework, the inverse distance weighting interpolation algorithm in ArcGIS 10.8 software, and Microsoft Excel were deployed in data analyses. In general, the results showed remarkable seasonal oscillation in the mean concentration of CO, with peak values in January and February, while the lowest mean concentration was observed in October. Higher values of NO were observed2 from November to February and the lowest values in July. July also recorded the highest SO values, with the lowest mean2 observable atmospheric concentrations in August, in addition to remarkable insignificant values in 2020–2022. Besides, the 12 geospatial models (maps) also depicted the spatio-temporal distribution of CO, NO , and SO concentrations from 2019 to2 2 2022 for easy visualization and facilitation of workable policies towards global warming mitigation. The paper recommended the establishment of well-equipped and functional ground-based GHG observatories with early warning systems across the state. This will facilitate real-time GHG monitoring, early warning forecasts, and stimulate scholarship on global warming and climate change.

Spatial distribution and policy implications of the exhaust emissions of two-stroke motorcycle taxis: a case study of southwestern state in Nigeria

Two-stroke motorcycles emit harmful exhaust fumes because of incomplete combustion. Although they constitute the main fleet of motorcycle taxis in sub-Saharan Africa, monitoring, spatial assessment, and regulation are weak, leaving dire health consequences in cities. This study collected motorcycle raw exhaust emissions of 1,950 two-stroke petrol-driven motorcycle taxis, otherwise called okada, in Ogun State, Nigeria, using an idle mode test approach under 10 minutes and employed correlations, hierarchical multiple linear regression models, and spatial analysis. It was found that carbon monoxide (CO) and hydrocarbons (HC) were the most highly concentrated, and the latter were beyond allowable limits. The concentration of CO was found to be at the minimum of 0.00 % and the highest being at 6.40% (an average of 1.05%), while the HC concentration was reported at the minimum of 18.00 ppm and the highest at 15446 ppm (an average of 3560 ppm). Notably, Kriging interpolation analysis indicated that cumulative effects due to the clustering and operations of motorcycle taxis could increase these concentrations over time, extending their long-term impacts. Given the severe effects of these emissions on health and the wider environment, a DPSIR policy framework is proposed to regulate two-stroke motorcycle taxis in sub-Saharan Africa.