Carbon Monoxide Emission Factors Research Articles

The Effects of Varying Altitudes on the Rates of Emissions from Diesel and Gasoline Vehicles Using a Portable Emission Measurement System

The high altitude in mountainous regions results in lower atmospheric pressure, oxygen concentration and temperature, leading to lower combustion efficiency in motor vehicles. Therefore, there may be differences in carbon dioxide (CO2), carbon monoxide (CO), and nitrogen oxides (NOx) emissions characteristics at different altitudes. In this study, a portable emission measurement system was used to investigate the effects of varying elevations on the emission factors of CO2, CO, and NOx on diesel and gasoline-powered vehicles at altitudes ranging from 2270 to 4540 m in the Qinghai–Tibet Plateau of China. Additionally, the influencing factors of CO2, CO, and NOx emissions were studied. Results showed that the CO2, CO, and NOx emission factors for diesel vehicles varied in the range of 161.83–195.54, 0.59–0.77, and 4.61–6.58 g/km; the population means with 90% confidence intervals were 178.54, 0.68, and 5.60 g/km, respectively. For gasoline vehicles, the CO2, CO, and NOx emission factors varied in the range of 161.66–181.98, 0.95–1.06, and 0.12–0.25 g/km; the population means with 90% confidence intervals were 171.82, 1.01, and 0.19 g/km, respectively. Overall, the emission factors of diesel vehicles were higher than those of gasoline vehicles, and the emissions increased with increasing altitude. Atmospheric pressure was identified as the primary environmental factor affecting CO2, CO, and NOx emissions. As the speed of motor vehicles increased, the emission of CO2 also increased, while there was a quadratic relationship with acceleration. This study provides a reference and guidance for vehicle pollution control in high-altitude regions.

Quantification of carbon monoxide emissions from African cities using TROPOMI

Abstract. Carbon monoxide (CO) is an air pollutant that plays an important role in atmospheric chemistry and is mostly emitted by forest fires and incomplete combustion in, for example, road transport, residential heating, and industry. As CO is co-emitted with fossil fuel CO2 combustion emissions, it can be used as a proxy for CO2. Following the Paris Agreement, there is a need for independent verification of reported activity-based bottom-up CO2 emissions through atmospheric measurements. CO can be observed daily at a global scale with the TROPOspheric Monitoring Instrument (TROPOMI) satellite instrument with daily global coverage at a resolution down to 5.5 × 7 km2. To take advantage of this unique TROPOMI dataset, we develop a cross-sectional flux-based emission quantification method that can be applied to quantify emissions from a large number of cities, without relying on computationally expensive inversions. We focus on Africa as a region with quickly growing cities and large uncertainties in current emission estimates. We use a full year of high-resolution Weather Research and Forecasting (WRF) simulations over three cities to evaluate and optimize the performance of our cross-sectional flux emission quantification method and show its reliability down to emission rates of 0.1 Tg CO yr−1. Comparison of the TROPOMI-based emission estimates to the Dynamics–Aerosol–Chemistry–Cloud Interactions in West Africa (DACCIWA) and Emissions Database for Global Atmospheric Research (EDGAR) bottom-up inventories shows that CO emission rates in northern Africa are underestimated in EDGAR, suggesting overestimated combustion efficiencies. We see the opposite when comparing TROPOMI to the DACCIWA inventory in South Africa and Côte d'Ivoire, where CO emission factors appear to be overestimated. Over Lagos and Kano (Nigeria) we find that potential errors in the spatial disaggregation of national emissions cause errors in DACCIWA and EDGAR respectively. Finally, we show that our computationally efficient quantification method combined with the daily TROPOMI observations can identify a weekend effect in the road-transport-dominated CO emissions from Cairo and Algiers.

Quantification of Gaseous and Particulate Emission Factors from a Cargo Ship on the Huangpu River

Exhaust emissions from ships have garnered significant attention because of their impact on global climate change, deterioration of air quality, and potential risks to human health. Consequently, it is necessary and urgent to quantify the gaseous and particulate emission factors (EFs) of ships in a local area. In order to supplement native EF profile data, an inland cargo ship in China was selected for measuring gaseous and particle pollutants under real-world operation modes. The fuel-based EFs of carbon dioxide, carbon monoxide (CO), nitrogen oxides, and hydrocarbons (THC) were 2965–3144 g/kg, 8.04–83.53 g/kg, 64.51–126.20 g/kg, and 3.90–23.35 g/kg, respectively. The maximum values of CO EF and THC EF were achieved under idling mode, which were 10.4 and 5.3 times those observed under cruising (500 rpm) mode, as extremely poor engine loads under idling mode can result in low temperature, low pressure, and uneven mixture of air and fuel. Organic carbon and element carbon were identified as the most abundant compositions of particulate matter (PM). Ions and elements were primarily dominated by SO42− and S, which can be attributed to the utilization of fuels with high sulfur content. Additionally, hopanes (dominated by 17α(H),21β(H)-Hopane and 17α(H),21β(H)-29-Norhopane) and fatty acids (dominated by n-Hexadecanoic acid and n-Octadecanoic acid) have the potential to serve as tracers for ship exhaust emissions. Pyrene and fluoranthene, two EPA priority polycyclic aromatic hydrocarbons (PAHs), were identified as the major constituents of PAHs and accounted for 50% of total PAHs. This finding also provides an explanation for the significant contribution of four-ring PAHs to the total PAHs mass.

Altitude-dependent gaseous emissions from freight trucks along the China-Pakistan Economic Corridor in Pakistan.

Recent increases in emissions from freight transport have caused strong concerns about air quality in Pakistan, following the rapid development of projects related to the China-Pakistan Economic Corridor (CPEC). This study reported the first measurements of on-road truck emissions in Pakistan and investigated their dependence on altitude along CPEC routes. Emissions from 70 trucks were measured on CPEC highways located in Islamabad (540m above sea level), Sost (2800m above sea level), and at the Khunjerab Pass (4693m above sea level). Calculated emission factors for carbon monoxide, hydrocarbons, and nitrogen oxides from heavy-duty trucks in Islamabad were 12.94±1.46, 15.21±1.67, and 10.69±1.34gkm-1 (95% confidence level), respectively, for pre-Pak-II trucks, and 12.75±2.80, 14.24±3.53, and 10.24±2.34gkm-1 (95% confidence level), respectively, for Pak-II trucks, representing 2-20 times higher values than the emission standards in Pakistan and India. An altitude increase of approximately 4000m, with the associated changes in meteorology and fleet characteristics, induced an average increase of 103.6%, 86.3%, 124.5%, and 133.6% in the emission factors of carbon monoxide, hydrocarbons, nitrogen oxides, and carbon dioxide, respectively. Moreover, on-road emissions along the CPEC were mainly influenced by truck types. This study will support the budget evaluation of transport emissions from the CPEC trade fleet.

Estimation of biomass burning emission of NO2 and CO from 2019–2020 Australia fires based on satellite observations

Abstract. The bushfires that occurred in Australia in late 2019 and early 2020 were unprecedented in terms of their scale, intensity, and impacts. Using nitrogen dioxide (NO2) and carbon monoxide (CO) data measured by the Tropospheric Monitoring Instrument (TROPOMI), together with fire counts and fire radiative power (FRP) from MODIS, we analyzed the temporal and spatial variation of NO2 and CO column densities over three selected areas covering savanna and temperate forest vegetation. The ΔNO2/ΔCO emission ratio and emission factor were also estimated. The ΔNO2/ΔCO emission ratio was found to be 1.57 ± 1.71 for temperate forest fire and ranged from 2.0 ± 2.36 to 2.6 ± 1.92 for savanna fire. For savanna and temperate forest fires, satellite-derived NOx emission factors were found to be 1.48 and 2.39 g kg−1, respectively, whereas the CO emission factors are 107.39 and 126.32 g kg−1, respectively. This study demonstrates that the large-scale emission ratio from the TROPOMI satellite for different biomass burnings can help identify the relative contribution of smoldering and flaming activities in a large region and their impacts on the regional atmospheric composition and air quality. This method can be applied to study the emissions from other large fires, or even the burning of fossil fuel in megacities, and their impact on air quality.

Insight into the penalty of exhaust emissions and fuel consumption by DPF regeneration of a diesel passenger car

In order to keep high fuel economy of diesel passenger cars, Diesel particulate filter (DPF) is periodically regenerated. In the regeneration process, extra fuel is injected into combustion chambers to achieve high exhaust temperature for the purpose of oxidizing particles accumulating on DPF substrate. It generates significant impacts on passenger car performance and exhaust emissions. In this paper, real-driving performance and exhaust emissions of a diesel car were tested over sixteen drivers under real-world conditions. DPF regeneration events were identified via exhaust temperature. Vehicle power output, fuel economy, and exhaust emissions in the trips both with and without DPF regeneration were analyzed. The results indicated that DPF regeneration events occurred in three of thirty-two test trips, and the maximum exhaust temperature was 250 °C during DPF regeneration. The DPF regeneration event led to the decrease of fuel economy and the increase of particle number, nitrogen oxides and carbon dioxides emission. Particle number emission factors were increased from approximately 109 #/km to 5 × 1010 #/km during DPF regeneration. The average power output of the car was in the range of 14.5 kW–15.6 kW and 15.8 kW–18.4 kW for the trips with and without DPF regeneration, respectively. However, Carbon monoxide emission factors were insensitive to DPF regeneration in the test trips.

Air pollutant emissions from sludge-bituminous briquettes as a potential household energy source

To promote the sustainable and clean use of sewage sludge (SS) and bituminous coal (BC), BC was mixed with SS at 2%, 4% and 16% as sludge-coal briquettes (named by SBC1, SBC2 and SBC3) which were characterized in this study to evaluate combustion performance and emissions of hazardous air pollutants in an advanced residential stove. Fuel burning rate and modified combustion efficiency (MCE) were similar among the three fuels, while the emission factors of carbon monoxide (CO) and mercury (Hg) were significantly different ( p < 0.05), with the highest emissions from the biomass-coal briquette with the sludge content of 4%. Ash content is a key factor affecting the emission factors (EFs) of CO and Hg. EFs of particulate matter with aerodynamic equivalent diameter ≤2.5 μm (PM 2.5 ) was significantly correlated with the EFs of nitrogen oxides (NO x ), cadmium (Cd) and total polycyclic aromatic hydrocarbons (tPAHs). It appears that by mixing sludge with briquettes at 16%, there were insignificant changes in emissions of most hazardous pollutants including Hg and PAHs compared with mixing sludge at 2%. This study suggested possibilities in support of high-efficient co-utilization of sludge and briquette coals especially in the residential sector.

Road Grade Estimation Based on Power Demand Difference of Heavy-Duty Diesel Trucks for Emission Estimation

Road grades have significant impacts on the emissions of heavy-duty diesel trucks (HDDTs), even in the same operating mode. Existing gradient identification methods are time-consuming and difficult to conduct for entire road networks; moreover, few previous studies have considered uncertainty of HDDT emissions caused by various road grades. In this study, an estimation method for road grade was developed based on second-by-second field operating data, with noise reduction performed using the Kalman filter. The consistency and symmetry of the road grade calculated by the proposed method were then analyzed. Finally, differences in emission rate and emission factor for carbon dioxide (CO2), carbon monoxide (CO), total hydrocarbon (THC), and nitrogen oxides (NOx) under various grades were compared. The results indicated that the grade recognition results of each truck were consistent, with an average grade difference of 0.153%. Based on symmetry analysis of the estimation results in opposite directions, the two opposite road grades were found to have a strong negative correlation, and the average error of the grade was 0.125%. Pollutant results showed the emission rate of CO was most affected by grade, followed by NOx, and THC was the least affected. The emission factors of CO2, CO, THC, and NOx were found to increase by 32.4% to 82.8%, 75.6% to 198.4%, 19.9% to 39.9%, and 73.1% to 186.3%, respectively at 1.0%, 2.0%, and 3.0% gradients compared with 0.0% gradient. This study can improve the estimation accuracy for HDDT emissions, especially in areas with undulating terrain such as mountains and hills.

Dynamic relationships between real-time fuel moisture content and combustion-emission-performance characteristics of wood pellets in a top-lit updraft cookstove

Fuel moisture content (FMC) has an essential impact on the performance of biomass combustion. FMC typically changes during the burning process; therefore, considering only the initial FMC is inadequate for understanding clean combustion and emission control. An on-line FMC monitoring method was employed by measuring relative humidity of emissions to determine the real-time effect of FMC on modified combustion efficiency (MCE) and emission factors (EFs) of pollutants from a typical top-lit updraft cookstove fueled with wood pellets. The results obtained from a complete 16-h combustion sequence showed an overall decreasing trend of FMC, consequently increasing combustion temperature and MCE. Flaming combustion appeared in a high-power phase where the EFs of carbon monoxide (CO) and fine particulate matter (PM2.5) decreased while real-time FMC decreased from 3.5% to 2.1% (wet basis). Smoldering combustion was generally dominant in a low-power phase where EFs of CO and nitric oxide (NO) decreased, while PM2.5 increased with real-time FMC decreasing from 6.3% to 4.9% (wet basis). This paper can provide meaningful information for modeling biomass burning, quantifying pollutant emissions and understanding related impacts on the residential sector.

Real-world emissions and fuel consumption of gasoline and hybrid light duty vehicles under local and regulatory drive cycles

In this study, driving trajectory data from private vehicles were collected in Toronto, Canada to construct representative local drive cycles. In addition, real-driving emission testing for four conventional gasoline vehicles (ICEV) and one hybrid electric vehicle (HEV) was conducted in the same region using a Portable Emissions Measurement System. Instantaneous fuel consumption and emissions of Carbon Monoxide (CO), Nitrogen Oxides (NOx), and Particle Number (PN) were measured. The results for all vehicles indicate that the acceleration state tends to generate the highest emissions and fuel consumption with the largest variation due to higher power demand. When accelerating, the HEV was observed to generate four times more CO emissions than some ICEVs. Instantaneous fuel consumption and emissions were analyzed as a function of operating modes to estimate the fuel efficiency (FE) and emission factors (EF) associated with six representative local drive cycles and four regulatory drive cycles. With most regulatory drive cycles, vehicles can reach the labeled FE and EPA emission limits, except under the New York City Cycle with frequent stop-and-go conditions. In contrast, except for highway cycles, the FE of Toronto-specific drive cycles can hardly meet the labeled values. CO EFs of the HEV can be higher than ICEVs, while it is lower than the emission limit by 42% on average. ICEVs may exceed the CO limit by 131% under local highway cycles, while they can violate NOx and PN limits under local arterial cycles. The result of this study emphasizes the importance of local drive cycles and real driving emission tests.

Effects of road grade on real-world tailpipe emissions of regulated gaseous pollutants and volatile organic compounds for a Euro 5 motorcycle

Road grade is an important variable that affects engine power demand and hence the fuel consumption and tailpipe emissions of vehicles. However, no prior works have evaluated the effects of road grade on tailpipe volatile organic compound (VOC) emissions of motorcycles. This study investigated the effects of road grade on real-world tailpipe emissions of carbon monoxide (CO), carbon dioxide (CO2), total hydrocarbons (THC), nitric oxide (NO), and speciated VOCs for a Euro 5 motorcycle. Real-world emissions of CO, CO2, THC, and NO were measured in real-time using a miniature portable emissions measurement system (mini-PEMS), while VOCs were measured in integrated exhaust samples collected during real-world driving. PEMS tests (n = 20) were conducted on urban (UR), suburban (SU), uphill (UH), and downhill (DH) routes. The road grade range encountered in this study was approximately −14 % to +14 %. The mean UH emission factors of CO, THC, and ΣVOC were 9890 ± 1619, 101.0 ± 6.7, and 18.81 ± 4.31 mg/km, respectively. Likewise, the DH emission factors were 202 ± 197 mg/km for CO, 10.3 ± 2.9 mg/km for THC, and 1.49 ± 0.68 mg/km for ΣVOC. The emission factors of all measured pollutants on the UH route were significantly higher than the DH and baseline (mean of UR and SU) emission factors. The results of the present study may help identify emission hotspots along the roads and formulate traffic air pollution control strategies.

Research on the real-world gaseous emission characteristics of a plug-in hybrid electric vehicle under different initial battery state-of-charge

Plug-in hybrid electric vehicles (PHEVs) have been greatly promoted due to their advantage in both vehicle performance and energy conversion efficiency. However, real-world emission measurements are rarely conducted for PHEV under different initial battery state-of-charge (SoC). In this study, a portable emission measurement system (PEMS) was employed to investigate the real-world emissions of carbon monoxide (CO), nitrogen oxides (NOx), and carbon dioxide (CO2) from a Euro V PHEV under fully and uncharged initial battery SoC. Compared to the emissions under the uncharged state, the average emission factors (EFs) of CO, NOx, and CO2 under the fully charged state are reduced by 72.2%, 27.8%, and 29.0%, respectively. And the reduction effect on the urban road is much more significantly prominent compared to that on the rural road and highway. In addition, obvious reduction effectiveness can be found for CO EFs in different average speed bins, especially those with speeds above 100 km/h. For NOx and CO2, however, the average speed-bin EFs are reduced only when the speed is below 70 km/h, while no obvious differences can be found when the speed is above 70 km/h. Furthermore, for the average vehicle specific power (VSP)-bin emission rates, obvious reduction effectiveness is observed for CO in different speed ranges, and for NOx and CO2 in the low- and medium-speed ranges except the high-speed range.

Effects of Vehicle Load on Emissions of Heavy-Duty Diesel Trucks: A Study Based on Real-World Data.

Vehicle loads have significant impacts on the emissions of heavy-duty trucks, even in the same traffic conditions. Few studies exist covering the differences in emissions of diesel semi-trailer towing trucks (DSTTTs) with different loads, although these vehicles have a wide load range. In this context, the operating modes and emission rates of DSTTTs were analyzed under varying loads scenarios to understand the effect of vehicle loads on emission factors. First, second-by-second field speed data and emission data of DSTTTs with different loads were collected. Then, the methods for calculating the scaled tractive power (STP) and the emissions model for DSTTTs were proposed to evaluate the effect of different loading scenarios. The STP distributions, emission rate distributions, and emission factor characteristics of different loaded trucks were analyzed and compared. The results indicated that the STP distributions of DSTTTs that under the unloaded state were more narrow than those under fully loaded or overloaded conditions. The emission rates of carbon dioxide (CO2), carbon monoxide (CO) and total hydrocarbon (THC) for DSTTTs under a fully loaded state were significantly higher than those under an unloaded state. However, due to the influence of exhaust temperature, the emission rates of nitrogen oxides (NOx) among fully loaded trucks were lower than those under the unloaded state when STP bin was above 4 kW/ton. The emission factors of CO2, CO, THC, and NOx for fully loaded trucks demonstrated the largest increases at low-speed intervals (0–30 km/h), which rose by 96.2%, 47.9%, 27.8%, and 65.2%, respectively.

Real-world emissions of construction mobile machines and comparison to a non-road emission model

This study implemented real-world tests in Nanjing, China for measuring emission factors (EFs) of air pollutants, including Carbon Monoxide (CO), Hydrocarbon (HC), Nitrogen Oxides (NOx), and Particulate Matter (PM) from ten construction machines in three operational modes (idling, moving, and working) with a Portable Emission Measurement System. The idling mode shows the least variation of EFs, and its average CO EFs can be higher than the moving and working modes by 43% and 34%, respectively. The working mode generates the highest emission for all other pollutants with the highest variation. The EFs suggested by the Guide (an official guidebook for developing emission inventory in China) are in general lower than the measured EFs, and the gap becomes larger for older machines. The EFs of CO, NOx, and PM of China Stage II machines are 24%, 120%, and 66% higher than those of the Guide, respectively. The differences go up as high as 126%, 1066%, and 559% for China Stage I machines, indicating the upgrade of engine technology from Stage I to Stage II, as well as the effect of machine deterioration. The result of this study reveals the effectiveness of stringent emission standards in controlling emissions from construction machines. High emissions from older machines emphasize the importance of a more rigorous machine replacement policy and a regulated maintenance strategy. The result also stresses the need to update the Guide with differentiated activity modes, region variations, and machine deterioration effects.

Characterization of PM, PAHs and Gaseous Pollutants Emitted from Sintering Process and Electric Arc Furnace

ABSTRACT Iron and steel industry is crucial for economic development. However, large exhaust volume and complex feeding of the steel-making process results in enormous emissions of air pollutants such as particulate matter (PM), sulfur oxides (SOx), nitrogen oxides (NOx), polycyclic aromatic hydrocarbon (PAHs) and carbon monoxide (CO). This study sampled and analyzed the concentrations of PM, PAHs, SOx, NOx and CO at the inlet and outlet of the air pollution control devices (APCDs) adopted in sintering process (SP) and electric arc furnaces (EAF), respectively, to evaluate the performance of APCDs and emission characteristics of these air pollutants. The results show that filterable PM (FPM) concentrations measured at stacks of SP and EAF are 8.2 ± 1.3 and 13.6 ± 2.2 mg Nm–3, respectively. The FPM2.5 concentrations emitted from SP and EAF are 1.8 ± 0.5 and 3.2 ± 1.1 mg Nm–3, respectively, while the condensable PM (CPM) concentrations emitted from SP and EAF are measured as 37.7 ± 1.3 and 3.4 ± 0.8 mg Nm–3, respectively. Moreover, the flue gas desulfurization (FGD) and selective catalytic reduction (SCR) equipped in SP removed 82% and 58% of SOx and NOx, respectively, whereas SOx and NOx emitted from EAF are relatively low (< 1 ppm). The overall PAH removal efficiencies achieved with the APCDs adopted by SP and EAF are 72% and 26%, respectively. For total toxicity equivalency quantity (TEQ) PAH concentrations, similar results for SP (5.45 µg-BaPeq Nm–3) and EAF (4.74 µg-BaPeq Nm–3) are obtained. Moreover, the diagnosis ratios of FL/CHR, FL/(BaA + CHR), Pyr/5-MC and Pyr/(BaA + CHR) are suggested as the indicators for EAF. The emission factors calculated indicate that operating conditions of the APCDs in the SP investigated are well controlled. The concentrations of air pollutants emitted from SP investigated are lower than other studies. On the other hand, the concentrations of FPM and PM2.5 emitted from EAF are higher than other studies. However, NOx, SOx and PAHs are well controlled. Moreover, the CO emission factors calculated from these two steel-making processes are higher than most reports. Overall, the operation of APCDs should be improved to reduce air pollutants emitted from these two steel-making processes.

Emission factors of some common grass species in West Africa.

Frequent burnings occurring in the grasslands of the West African region during the dry seasons largely contribute to emissions of trace gases and particulates being released into the ambient environment, which has significantly impacted both regional and global climate patterns. Burning potentials of forty different grassland biomes were examined by determining their Net Heating Value (NHV) and Total Organic Carbon (TOC). Simulations of the field operations which involve open burning were performed in the laboratory using a fabricated combustion chamber for the determination of emission factors. Particulates were collected using Whatman quartz fibre filters and analyzed gravimetrically. Emissions of gaseous pollutants from open burning of these common grass species were measured with portable devices. The values of the NHV and TOC of the grass species ranged from 15,022.19 to 18,181.84 kJ/kg and 21.14 to 55.62%, respectively. The average Emission Factors (EFs) obtained for carbon dioxide (CO2), carbon monoxide (CO), sulphur dioxide (SO2), nitrogen dioxide (NO2), volatile organic compounds (VOC), and PM2.5 are 1465.55 g/kg, 40.99 g/kg, 0.39 g/kg, 0.02 g/kg, 7.78 g/kg, and 6.00 g/kg, respectively. The study has shown that Digitaria nuda, Digitaria eriantha, Panicum subalbidum, Paspalum polystratchyum, and Perotis indica have the highest emission factors for CO2, CO, SO2, NO2, VOC, and PM2.5, respectively. The result obtained would help in the quantification of the global warming forcing on the climate in the West African region from grassland burnings. The results will potentially serve as additional information for emission inventories and basis for the formulation of mitigation strategies.

Efficiency of improved cookstoves and emission of Carbon Monoxide and Carbon Dioxide: An intervention study in Northern Ghana

Title: Efficiency of improved cookstoves and emission of Carbon Monoxide and Carbon Dioxide: an intervention study in Northern Ghana AbstractBiomass burning for home energy use is a major environmental health concern. Improved cooking technologies could generate environmental health benefits, yet prior results regarding reduced exposure to air pollution from improve cookstoves are mixed. In this study, 20 in-field uncontrolled cooking tests were conducted in domestic settings to assess the emission and efficiency of the Ace and the Jumbo stoves using the Emission Pod (EPOD) to measure emissions in real-time. Carbon Dioxide (CO2) and Carbon Monoxide (CO) emissions, Emission Factors (EF), Modified Combustion Efficiency (MCE) and Cooking time were all calculated across a variety of meal types using the two stoves. Overall average CO emission was estimated at 248.71±44.66 ppm for the Ace stove while that of the Jumbo stove was calculated to be 103.66±24.4 ppm (P=0.024). The Jumbo stove had a higher MCE of 0.93 against the Ace stove (0.84). Using the partial capture Carbon Balance Method (CBM), EF was calculated for both stoves with the Ace recording a CO EF of 1425.04 g/kg and CO2 EF of 1318.35 g/kg. The Jumbo, on the other hand, had a CO EF of 151.57 g/kg and a CO2 EF of 1215.82 g/kg. The study concluded that although the stoves had better performance in most of the parameters studied compared to other stove interventions in the literature, they still fell short when compared with some of the traditional cooking methods. While the Jumbo falls within the International Workshop Agreement (IWA) tier 4 category guidelines for cookstove, the Ace stove which is much fancier falls in WHO-IWA category 0.

Dependence of pollutant emission factors and fuel consumption on driving conditions and gasoline vehicle types

Vehicle types, technologies, and driving conditions are key factors affecting emission factors and fuel consumption. In this study, we measured the hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxide (NOx) emission factors, and fuel consumption of vehicles with a (1) carburetor (CVs), (2) multipoint injection technology and three-way catalyst (MTVs), and (3) multipoint injection technology, three-way catalyst, and exhaust gas recirculation device (MTEVs) under real driving conditions using an OBS-2200 portable emission measurement system. The results showed that both the distance- and fuel-based HC, CO, and NOx emission factors of CVs were 2.7–6.6 times higher than those of MTVs and MTEVs. The average incomplete fuel conversion rates (IFCRs) of CVs were 3.8 and 4.4 times higher than those of MTVs and MTEVs, respectively. The molar ratios of the CO/HC pollutants were 7.6, 5.6, and 2.8 for CVs, MTVs, and MTEVs. Furthermore, the correlation between the vehicle-specific power and fuel consumption rate was significant. The exhaust gas recirculation (EGR) system could improve the fuel combustion efficiency and reduce vehicle emissions, particularly under high-speed and acceleration conditions.

The effect of cold-start emissions on the diurnal variation of carbon monoxide concentration in a city centre

The diurnal variation of pollutants such as particles and carbon monoxide (CO) in urban environments typically follow the traffic density, with two peaks coinciding with the weekday morning and evening rush-hour periods. However, observations made in central Brisbane, the third largest city in Australia, demonstrated an anomalous diurnal variation with the CO peak in the evening being significantly higher than that in the morning. This imbalance was not observed for particle concentrations. Here, we show that the imbalance is a direct result of the difference in CO emission factors from motor vehicles during warm and cold starts. Over 30,000 cars with warmed-up engines enter Brisbane city centre car parks every weekday morning. They all start their engines from cold and leave the city in the evening, producing the anomalously higher emissions of CO in the city centre. This pattern of air quality, while clearly apparent within the city car parks and within the central business district of the city, was not observed outside the city limits and in the suburbs. To the best of our knowledge, no previous study has drawn attention to this phenomenon and no explanation has been provided in the literature to-date.

Characteristics of the real-driving emissions from gasoline passenger vehicles in the Kuala Lumpur urban environment

Emission factors (EFs) are empirical functions that envisage the amount of an emitted pollutant based on travel activity and vehicle characteristics. This paper aims to estimate on-road gaseous emission factors of gasoline passenger vehicles under urban Malaysian road traffic conditions. Eleven vehicles were tested and the carbon monoxide (CO), carbon dioxide (CO2) and nitrogen oxides (NOx) emission results were analyzed according to driving conditions. The effects of inter-vehicle variability in terms of accumulated mileage on emission factors were explored using regression analysis. The links of real driving condition on exhaust emissions were examined using hierarchical cluster analysis. The emission factors of CO, CO2 and NOx were calculated using a fuel-based approach. The 95% confidence intervals obtained for the population mean of emission factors were CO: 0.76 ± 0.15 g/km, CO2: 236.02 ± 14.98 g/km, NOx: 0.23 ± 0.03 g/km. Vehicle age as echoed by accumulated mileage was responsible for the increase in the average emission factors of CO and NOx. The results of the cluster analysis formed four meaningful clusters which described driving conditions and exhaust emissions. Higher observations were recorded for Cluster 1 (43.25%) indicating low vehicle speed and better fuel efficiency produced low NOx and CO emissions but high CO2 emissions. The measurements reported in this paper highlight the significance of this work in quantifying CO, CO2 and NOx emissions from gasoline passenger vehicles under real-world driving conditions of urban street in Malaysia where there is a paucity of EFs studies.