Carbon Monoxide Emission Rates Research Articles

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.

The impact of oxygen content in the primary air supply on fuel burning rate and pollutant emissions in a forced-draft biomass stove

Forced-draft biomass stoves have been proposed as a substitute for traditional solid fuel stoves in rural areas. The change in the O2 content of the supply air via flue gas recirculation (FGR) significantly affects the combustion and pollutant emission performances of this household stove type, which has not been thoroughly investigated. In this study, O2 content control system was designed to accurately adjust the O2 content of the primary air supply for a typical household forced-draft biomass stove. Then, six conditions with an O2 content of 16%, 17%, 18%, 19%, 20%, and 21% were tested. The dynamic burning rate and emission rates of carbon monoxide (CO), nitrous oxides (NOx), and particulate matter with an aerodynamic diameter ≤ 2.5 μm (PM2.5) were measured for each O2 content. The results showed that the average burning rate of the six O2 contents ranged from 9.6 to 16.9 g/min. There was a positive linear relationship between the average burning rate and the O2 content in the primary air supply. The CO and PM2.5 emission amounts exhibited the concave and convex quadratic relationships with O2 content, respectively, while trends in NOx emission amount had a negative linear relationship with the O2 content. The real-time burning rate and pollutant emission rates exhibited different trends that influenced the amount of emissions. When FGR was utilized with a constant primary airflow rate, an O2 content of 19.7% may be optimal for household biomass stoves. This study provides basic information on air supply design of household biomass stoves, which is essential for future clean stove design and improvement.

Characterization of Exhaust CO, HC and NOx Emissions from Light-Duty Vehicles under Real Driving Conditions

On-road exhaust emissions from light-duty vehicles are greatly influenced by driving conditions. In this study, two light-duty passenger cars (LDPCs) and three light-duty diesel trucks (LDDTs) were tested to investigate the on-road emission factors (EFs) with a portable emission measurement system. Emission characteristics of carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxides (NOx) emitted from vehicles at different speeds, accelerations and vehicle specific power (VSP) were analyzed. The results demonstrated that road conditions have significant impacts on regulated gaseous emissions. CO, NOx, and HC emissions from light-duty vehicles on urban roads increased by 1.1–1.5, 1.2–1.4, and 1.9–2.6 times compared with those on suburban and highway roads, respectively. There was a rough positive relationship between transient CO, NOx, and HC emission rates and vehicle speeds, while the EFs decreased significantly with the speed decrease when speed ≤ 20 km/h. The emissions rates of NOx and HC tended to increase and then decrease as the acceleration increased and the peak occurred at 0 m/s2 without considering idling conditions. For HC and CO, the emission rates were low and changed gently with VSP when VSP < 0, while emission rates increased gradually with the VSP increase when VSP > 0. For NOx NOx emission rates were lower and had no obvious change when VSP < 0. However, NOx emissions were positively correlated with VSP, when VSP > 0.

Modeling the emissions of rural vehicles based on real-world driving cycles

Characterized by a high frequency of use, harsh working environments, poor maintenance, and low levels of emission controls, rural vehicles (RVs) are becoming an important source of air pollution. Our study used a portable emission measurement system (PEMS) to test the real-world emissions of 35 RVs on provincial, rural, and farm roads. The results show that high emission rates of carbon monoxide (CO) and hydrocarbons (HC) mainly occurred when accelerating at low speeds. However, high levels of nitrogen oxides (NOx) were emitted during high-speed acceleration. The particulate number (PN) of emissions was higher when the RVs were accelerating. According to the overall test results, the vehicle specific power (VSP) on the provincial road mostly ranged within (0, 3], accounting for 68.80% of the total. The VSP on rural and farm roads was concentrated within (0, 2] kW·ton−1, accounting for 67.09% and 76.64% of the total, respectively. We defined 14 bins based on the distribution of the VSP values and calculated the average emission rate of each bin. By comparing the average emission rate among the bins, we found that within Bins 1–7 (VSP < 0 kW·ton−1), CO, HC, and NOx emissions slowly increased as the VSP increased. In Bins 8–13 (VSP ≥ 0 kW·ton−1), the average emission rates of four pollutants increased as the VSP increased. However, all pollutants decreased in Bin 14 (VSP ≥ 6 kW·ton−1). We built a microscopic emission model according to the VSP distribution characteristics of RVs on different road types. We compared the measured and simulated emission factors and found that our emission model can greatly simulate the HC, NOx and PN emission factors of RVs.

Emission Characteristics of Light-Duty Gasoline Vehicle Exhaust Based on Acceleration Simulation Mode

In this study, 127 light-duty gasoline cars and 10 light-duty gasoline trucks with different emission standards were selected to explore the influences of different conditions and vehicle parameters on the emission characteristics of carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx), hydrocarbons (HC), and methane (CH4) using a portable emission measurement system based on a chassis dynamometer under acceleration simulation mode. The results showed that the gaseous pollutants of light-duty gasoline vehicles displayed a relatively lower emission rate under the idle condition, which accounted for only 22.9% and 25.8% of the emission rate at the accelerated condition and constant speed condition, respectively. The pollutant emission characteristics were closely related to the working conditions. The emission rates of CO2 and NOx in the accelerated condition were less than those at the constant speed condition, while the emission rates of CO, HC, and CH4 in the accelerated condition were higher than those at the constant speed condition. In the constant low-speed condition, the emission factors of CO2, CO, NOx, HC, and CH4 were 383.20, 2.98, 1.60, 0.14, and 0.03 g·km-1 for light-duty gasoline cars, respectively, and 360.66, 2.64, 1.61, 0.0055, and 0.0027 g·km-1 for light-duty gasoline trucks, respectively. Tighter emission standards have caused significant reductions in emissions. The emission factors of CO, NOx, HC, and CH4 could be decreased by 87.5%, 97.3%, 97.9%, and 86.4%, respectively, from China Ⅰ to China Ⅴ. A non-linear relationship was found between the age, odometer, vehicle weight, and vehicular emissions. In addition, the engine displacement was positively correlated with vehicular emissions.

Analysis of particulate matter and carbon monoxide emission rates from vehicles in a Shanghai tunnel

Underground road tunnels are becoming increasingly prevalent in cities as a means to alleviate ground traffic congestion, which in turn leads to air pollution near tunnel exits and an increase in the power consumption of ventilation systems. To investigate the characteristics of vehicle exhaust pollutants and human health damages (HHDs), we conducted tests in a typical Shanghai underground tunnel, in which real-time wind speeds, traffic volume rates, vehicle velocities, and traffic distribution were recorded. The prediction model of emission factors with motor vehicle emissions simulator (MOVES) was verified by comparing test results, the UNEP/SETAC toxicity (USEtox) Life Cycle model was adopted to assess the HHDs due to CO, PM2.5, and PM10, and the air-exchanging ventilation was analysed for potential pollution reduction. Results showed emission rates were reducing yearly and could be predicted with MOVES, PM10 had a greater impact on human health than PM2.5 in the tunnel ventilation, and complementary ventilation could improve the tunnel ventilation effects. The survey findings can be used to conduct a new quantitative assessment and an efficient control method for air pollution in city tunnel systems, and in turn improve the energy efficiency of existing underground tunnels.

Regional variability in black carbon and carbon monoxide ratio from long-term observations over East Asia: assessment of representativeness for black carbon (BC) and carbon monoxide (CO) emission inventories

Abstract. The black carbon (BC) and carbon monoxide (CO) emission ratios were estimated and compiled from long-term, harmonized observations of the ΔBC∕ΔCO ratios under conditions unaffected by wet deposition at four sites in East Asia, including two sites in South Korea (Baengnyeong and Gosan) and two sites in Japan (Noto and Fukuoka). Extended spatio-temporal coverage enabled estimation of the full seasonality and elucidation of the emission ratio in North Korea for the first time. The estimated ratios were used to validate the Regional Emission inventory in ASia (REAS) version 2.1 based on six study domains (“East China”, “North China”, “Northeast China”, South Korea, North Korea, and Japan). We found that the ΔBC∕ΔCO ratios from four sites converged into a narrow range (6.2–7.9 ng m−3 ppb−1), suggesting consistency in the results from independent observations and similarity in source profiles over the regions. The BC∕CO ratios from the REAS emission inventory (7.7 ng m−3 ppb−1 for East China – 23.2 ng m−3 ppb−1 for South Korea) were overestimated by factors of 1.1 for East China to 3.0 for South Korea, whereas the ratio for North Korea (3.7 ng m−3 ppb−1 from REAS) was underestimated by a factor of 2.0, most likely due to inaccurate emissions from the road transportation sector. Seasonal variation in the BC∕CO ratio from REAS was found to be the highest in winter (China and North Korea) or summer (South Korea and Japan), whereas the measured ΔBC∕ΔCO ratio was the highest in spring in all source regions, indicating the need for further characterization of the seasonality when creating a bottom-up emission inventory. At levels of administrative districts, overestimation in Seoul, the southwestern regions of South Korea, and Northeast China was noticeable, and underestimation was mainly observed in the western regions in North Korea, including Pyongyang. These diagnoses are useful for identifying regions where revisions in the inventory are necessary, providing guidance for the refinement of BC and CO emission rate estimates over East Asia.

Estimates of reactive trace gases (NMVOCs, CO and NOx) and their ozone forming potentials during forest fire over Southern Himalayan region

In the present study, emission of trace gases [non-methane volatile organic compounds (NMVOCs), carbon monoxide (CO) and oxides of nitrogen (NOx)], their ozone forming potentials and ozone sensitivities have been investigated during the forest fire period (2003–2016) over the Southern Himalayan region. Reanalysis data of Global Fire Assimilation System model is used to retrieve the various parameters such as fire radiative power and emission rates of various trace gases. April 2016 is noticed to be anomalous in terms of fire events in the last fourteen years (2003–2016) over the lower Southern Himalayan region. Our estimation shows major contribution of oxygenated compounds (55.2%) amidst all NMVOCs. Mean CO and NOx emission rates are 533.81 and 13.66 mg/m2/day, respectively during the forest fire of April months for fourteen years. The emissions of NMVOCs, CO and NOx increased by 90.4, 110.6 and 132.5% and reaches up to 121.1, 958.3 and 25.3 mg/m2/day in April 2016 with respect to non-burning period (April 2015). Ozone forming potentials (OFP) of NMVOCs are also examined using the maximum incremental reactivity (MIR) method, which shows ~2 times higher OFP for total NMVOCs during 2016 as compared to 2015. Based on the MIR scale, the contribution of top 10 species to OFP are in the decreasing order of formaldehyde, acetaldehyde, ethane, propene, toluene, butane, isoprene, methanol, pentene and hexane. The ratio of NMVOCs/NOx is <8, which indicates that the photochemical production of O3 is mainly controlled by the levels of NMVOCs. The surface observations of ozone and CO from a Himalayan station Nainital also showed substantial increase in concentration during the forest fire of April 2016. Our results are valuable for the better understanding of chemical composition of trace gases, their role in O3 formation and effective control strategies of O3 pollution during the forest fire events over the lower Himalayan region.

Comparison of real-world vehicle fuel use and tailpipe emissions for gasoline-ethanol fuel blends

Differences in fuel use and emission rates of carbon dioxide (CO2), carbon monoxide (CO), hydrocarbons (HC), nitrogen oxide (NOx), and particulate matter (PM) were quantified for three gasoline-ethanol blends and neat gasoline measured for one flexible-fuel vehicle (FFV) and four non-FFVs using a portable emission measurement system (PEMS). The purpose was to determine if non-FFVs can adapt to a mid-level blend and to compare the fuel use and emission rates among the fuels. Each vehicle was measured on neat gasoline (E0), 10% ethanol by volume (E10) “regular” (E10R) and “premium” (E10P), and 27% ethanol by volume (E27). Four real-world cycles were repeated for each vehicle with each fuel. Second-by-second fuel use and emission rates were binned into Vehicle Specific Power (VSP) modes. The modes were weighted according to real-world standard driving cycles. All vehicles, including the non-FFVs, were able to adapt to E27. Octane-induced efficiency gain was observed for higher octane fuels (E10P and E27) versus lower octane fuels (E0 and E10R). E27 tends to lower PM emission rates compared to E10R and E10P and CO emission rates compared to the other three fuels. HC emission rates for E27 were comparable to those of E10R and E10P. No significant difference was found in NOx emission rates for E27 versus the other fuels. Intervehicle variability in fuel use and emission rates was observed. Lessons learned regarding study design, vehicle selection, and sample size, and their implications are discussed.

Inventory of kiln stacks emissions and health risk assessment: Case of a cement industry in Southwest Nigeria

Cement production is a significant source of air pollution as both gaseous and particulate materials released are detrimental to the ecosystem. This work was carried out in a cement industry located in Southwest Nigeria. The emission rates of carbon monoxide (CO), nitrogen oxides (NOx), carbon dioxide (CO2) and sulphur oxides (SOx) released from the cement kilns using fuel oil, natural gas (NG) and coal were garnered for a year. Thereafter, the estimated emission quantities of the pollutants were employed to obtain the emission inventory of the cement plant. Uncertainty analysis associated with the emissions was evaluated using Analytica® (4.6). Total amounts of pollutants emitted from the plant were 4.86 tonne (t) (NOx), 18.2 t (SOx), 2.270 Kt (CO2) and 1.17 t (CO). Uncertainty range of –149.38% to 149.38% was connected to all the pollutants. Results showed that the quantities of pollutants discharged from the cement industry were considerably higher than recommended. The evaluated air quality indices for CO, NOx, and SOx implied that the health risk on exposure to these gases was hazardous. This study revealed that NG and wastes are the best fuel for kiln firing to reduce the amounts of pollutants emitted into the microenvironment of the plant.

Carbon monoxide emission rates from roasted whole bean and ground coffee

ABSTRACTCarbon monoxide (CO) emitted from roasted coffee is a potential occupational respiratory exposure hazard to workers within the coffee industry. The current study objective was to estimate CO emission factors from commercially available roasted whole bean and ground coffee measured in loose form, not packaged, and to assess the utility of CO monitoring in nonventilated storage spaces such as within coffee roasting and packaging facilities, transport vessels, and cafés. Determinants affecting CO emissions from coffee were investigated, including form (whole bean vs. ground), roast level (light, medium, medium-dark, dark), and age (time since the package was opened). CO emission factors were estimated for roasted coffee samples from a variety of manufacturers purchased from local grocery stores and online. Emission tests were performed on 36 brands of coffee, some with more than one sample per brand and with various roast levels. Decaying source equations or smoothing functions were fitted to the CO concentration measurements. Maximum observed emission factors at the peak of the predicted concentration curve were adjusted by the time required to reach the maximum CO concentration and reported as emission factors (EFbuildup). Ground coffee had a significantly increased EFbuildup (P < 0.0001) compared with whole bean. Roast level did not significantly affect emissions for whole bean (P = 0.72) but did for ground (P < 0.001) coffee. For ground coffee, medium-dark and dark roasts had significantly higher emissions than medium and light roasts. Worst-case emission factors from commercially available whole bean and ground coffee measured in loose form, not packaged, showed that roasted coffee can rapidly emit CO. CO concentrations should be monitored in storage spaces in service and manufacturing facilities as well as transport vessels to ensure exposures do not exceed occupational exposure limits. Storage spaces may need to be ventilated to control CO concentrations to safe levels.Implications: Emission rates of carbon monoxide (CO) from roasted coffee showed that unventilated or underventilated storage spaces should be monitored and ventilated, if necessary, to control CO concentrations to safe levels.

Top‐Down Estimates of NOx and CO Emissions From Washington, D.C.‐Baltimore During the WINTER Campaign

AbstractAirborne mass balance experiments were conducted around the Washington, D.C.‐Baltimore area using research aircraft from Purdue University and the University of Maryland to quantify emissions of nitrogen oxides (NOx = NO + NO2) and carbon monoxide (CO). The airborne mass balance experiments supported the Wintertime INvestigation of Transport, Emissions, and Reactivity (WINTER) campaign, an intensive airborne study of anthropogenic emissions along the Northeastern United States in February–March 2015, and the Fluxes of Atmospheric Greenhouse Gases in Maryland project which seeks to provide best estimates of anthropogenic emissions from the Washington, D.C.‐Baltimore area. Top‐down emission rates of NOx and CO estimated from the mass balance flights are compared with the Environmental Protection Agency's 2011 and 2014 National Emissions Inventory (NEI‐11 and NEI‐14). Inventory and observation‐derived NOx emission rates are consistent within the measurement uncertainty. Observed CO emission rates are a factor of 2 lower than reported by the NEI. The NEI's accuracy has been evaluated for decades by studies of anthropogenic emissions, yet despite continuous inventory updates, observation‐inventory discrepancies persist. WINTER NOx/CO2 enhancement ratios are consistent with inventories, but WINTER CO/NOx and CO/CO2 enhancement ratios are lower than those reported by other urban summertime studies, suggesting a strong influence of CO seasonal trends and/or nationwide CO reductions. There is a need for reliable observation‐based criterion pollutant emission rate measurements independent of the NEI. Such determinations could be supplied by the community's reporting of sector‐specific criteria pollutant/CO2 enhancement ratios and subsequent multiplication with currently available and forthcoming high‐resolution CO2 inventories.

Real-world fuel use and gaseous emission rates for flex fuel vehicles operated on E85 versus gasoline

ABSTRACTFlex fuel vehicles (FFVs) typically operate on gasoline or E85, an 85%/15% volume blend of ethanol and gasoline. Differences in FFV fuel use and tailpipe emission rates are quantified for E85 versus gasoline based on real-world measurements of five FFVs with a portable emissions measurement system (PEMS), supplemented chassis dynamometer data, and estimates from the Motor Vehicle Emission Simulator (MOVES) model. Because of inter-vehicle variability, an individual FFV may have higher nitrogen oxide (NOx) or carbon monoxide (CO) emission rates on E85 versus gasoline, even though average rates are lower. Based on PEMS data, the comparison of tailpipe emission rates for E85 versus gasoline is sensitive to vehicle-specific power (VSP). For example, although CO emission rates are lower for all VSP modes, they are proportionally lowest at higher VSP. Driving cycles with high power demand are more advantageous with respect to CO emissions, but less advantageous for NOx. Chassis dynamometer data are available for 121 FFVs at 50,000 useful life miles. Based on the dynamometer data, the average difference in tailpipe emissions for E85 versus gasoline is −23% for NOx, −30% for CO, and no significant difference for hydrocarbons (HC). To account for both the fuel cycle and tailpipe emissions from the vehicle, a life cycle inventory was conducted. Although tailpipe NOx emissions are lower for E85 versus gasoline for FFVs and thus benefit areas where the vehicles operate, the life cycle NOx emissions are higher because the NOx emissions generated during fuel production are higher. The fuel production emissions take place typically in rural areas. Although there are not significant differences in the total HC emissions, there are differences in HC speciation. The net effect of lower tailpipe NOx emissions and differences in HC speciation on ozone formation should be further evaluated.Implications: Reported comparisons of flex fuel vehicle (FFV) tailpipe emission rates for E85 versus gasoline have been inconsistent. To date, this is the most comprehensive evaluation of available and new data. The large range of inter-vehicle variability illustrates why prior studies based on small sample sizes led to apparently contradictory findings. E85 leads to significant reductions in tailpipe nitrogen oxide (NOx) and carbon monoxide (CO) emission rates compared with gasoline, indicating a potential benefit for ozone air quality management in NOx-limited areas. The comparison of FFV tailpipe emissions between E85 and gasoline is sensitive to power demand and driving cycles.

Low-cost measurement techniques to characterize the influence of home heating fuel on carbon monoxide in Navajo homes

A large fraction of the global population relies on the inefficient combustion of solid fuels for cooking and home heating, resulting in household exposure to combustion byproducts. In the southwestern United States, unhealthy air quality has been observed in some homes that use solid fuels as a primary source of heat on the Navajo Nation. In order to better understand how home heating fuel choice can influence indoor air quality in this region, we used recently developed low-cost electrochemical sensors to measure carbon monoxide (CO) air mole fractions continuously inside and outside 41 homes in two communities on the Navajo Nation. Using low-cost sensors in this study, which don't require extensive training to operate, enabled collaboration with local Diné College students and faculty in the planning and implementation of home deployments. Households used natural gas, propane, pellets, wood, and/or coal for heating. We developed quantification methods that included uncertainty estimation for Alphasense CO-B4 sensors, for measurements both inside and outside homes. CO concentrations elevated above background were observed in homes in each heating fuel group, but the highest hourly concentrations were observed in wood and coal burning homes, some of which exceeded World Health Organization Guidelines on both an hourly and eight-hourly basis. In order to probe the many factors that can influence indoor pollutant concentrations, we developed and implemented methods that employ CO emission and decay time periods observed in homes during everyday activities to estimate air exchange rates as well as CO emission rates on the basis of a given well-mixed volume of air. The air quality measurement tools and methods demonstrated in this study can be readily extended to indoor air quality studies in other communities around the world to inform how home heating and cooking practices are influencing indoor air quality during normal daily activities.

The Role of Vehicle Speed Management in Urban Air Pollutant Emission Reduction

Lack of mass transit facilities in urban area leads motorcycle to become the most chosen vehicle mode in Indonesia. It accounts for approximately 80% of the total motorized vehicle population. Increasing in motor vehicle population causes traffic congestion and lower traffic speed, hence higher emissions that worsen urban air quality. This paper aims to investigate relationship of vehicle travelling speeds and CO 2 , CO and HC emission profiles of the typical motorcycle used in Indonesia. Exhaust emissions of 20 motorcycles were tested using autocheck analyzer on idle and speed variations of, 10, 20, 30, 40, 50, and 60 kph on a chassis dynamometer. For idle condition average emission rates of CO 2 , CO and HC were 0.16, 0.03 and 0.002 g/s, respectively. The results show that the highest CO 2 and HC emissions of 82.30 g/km and 0.55 g/km, respectively, found at 10 kph. The lowest emissions were found at 60 kph speed with CO 2 emission rate of 27.03 g/km and HC of 0.10 g/km. Carbon monoxide (CO) showed slightly different emission pattern, with 12.85 g/km found at 20 kph and 4.18 g/km at 50 kph. In general, the result shows that the higher the speed the lower the CO 2 , CO, and HC emissions. Emission profiles indicate that the speed between 30-50 km/h could be recommended as the most suitable traffic speed in urban area to ensure mobility, safety as well as the lowest emissions. The results are valuable as input to transportation management as a part of environmentally sustainable transportation.

Operational level emissions modelling of on-road construction equipment through field data analysis

Abstract The construction industry is considered to be one of the largest contributors to greenhouse gas (GHG) emissions globally. Emissions from construction equipment are normally estimated through simulation or conducting emission tests in the laboratory, which may not represent real-world situations. Field data measurement is essential to quantify the emissions of equipment in use. This paper aims to develop an operational level model to estimate the emission rates of carbon monoxide (CO), carbon dioxide (CO 2 ), hydrocarbon (HC) and nitrogen oxides (NO x ) of on-road construction equipment. The data collection procedure included instrumentation, laboratory testing and field measurements. Three types of instruments, including a portable emission measurement system (PEMS), a global positioning system-aided inertial navigation system (GPS-INS) and an engine data logger, were used to collect emissions rates, operational parameters and engine data, respectively. The raw data collected from the three channels were then synchronized and validated. Further, the operational level emission model was developed by performing ordinary least square (OLS) and multivariable linear regression (MLR) analyses of the field data. The emission model considers engine specifications, operational factors and environmental parameters as affecting variables. The statistical analysis results verify the high correlation between emission rates and affecting parameters. The developed model is finally validated by comparing the estimated results with the real data collected by the PEMS and the engine data logger in the field experiments.

An assessment of gasoline motorcycle emissions performance and understanding their contribution to Tehran air pollution

Motorcycles are the third most common means of transportation in the megacity of Tehran. Hence, measurements of emission factors are essential for Tehran motorcycle fleets. In this study, 60 carburetor motorcycles of various mileages and engine displacement volumes were tested in a chassis dynamometer laboratory according to cold start Euro-3 emissions certification test procedures. For almost all of the tested samples, the average carbon monoxide (CO) emission factors were about seven times higher than the limits for Euro-3 certification. No motorcycle fell within the Euro-3 certification limit on CO emissions. 125cc engine displacement volume motorcycles, which are dominant in Tehran, have the most total unburned hydrocarbons and CO emission rates, and they have less nitrous oxides (NOX) emission rates and fuel consumption compared to those of larger engine volume motorcycles. Calculation of fuel-based emission factors and moles of combustion products shows that about 40% of fuel consumed by 125cc engine volume motorcycles burns to incomplete combustion products. This proportion is lower for larger engine volume motorcycles. Approximation of relative air–fuel ratio results shows very rich combustion in selected motorcycles. Using a carburetor fuel supply system, low engine compression ratio, aging, and no catalyst could be reasons for high emission rates. These reasons could possibly result in high ultrafine particles emission rates from motorcycles. Comparison of total motorcycle pollutant emissions to that of passenger cars from previous studies in Tehran shows that motorcycles contribute to pollutant much higher than their contribution to the total fleet or total travels.

Efficiencies and pollutant emissions from forced-draft biomass-pellet semi-gasifier stoves: Comparison of International and Chinese water boiling test protocols

Biomass fuels are widely combusted in rural China, producing numerous air pollutants with great adverse impacts on human health. Some improved cookstoves and pellet fuels have been promoted. To evaluate the performance of pellet-gasifier stoves, efficiencies and pollutant emissions were measured following International and Chinese water boiling tests (WBTs). Compared with traditional stoves and unprocessed biomass fuels, increased efficiencies and lower emissions of pollutants including carbon monoxide (CO), particulate matter (PM), parent and derivative polycyclic aromatic hydrocarbons (PAHs) were revealed for pellet-gasifier stoves. However, the calculated emission rates (ERs) of CO and PM2.5 cannot meet the ER targets recently suggested by WHO indoor air quality guidelines (IAQGs). Better control of air mixing ratio and gross flow rates of primary and secondary air supply greatly reduced emissions and increased efficiencies. Differences among testing protocols are the key factors affecting the evaluation of stove performance. With longer burning duration and higher power, the Chinese WBT had statistically higher efficiencies, gas temperature, and lower pollutant emissions (p<0.10) compared to those obtained through the International WBT. Statistically significant differences between the two protocols indicate the need for further efforts in emission tests and methodology development before the release of a well-accepted international testing protocol.

Measurement and Modeling of Carbon Monoxide Emission Rates from Multiple Wood Pellet Types

There is a potential hazard associated with bulk storage of wood pellets because they have been shown to off-gas carbon monoxide (CO). The risk to building occupants from the emission of and exposure to CO from stored pellets has not yet been fully studied. The present study was designed to measure the emission rates from wood pellets and develop a model to predict the CO emission rate. The 20 gallon steel drums were filled to approximately 50% of their volume with wood pellets and CO, and oxygen (O2), carbon dioxide (CO2), temperature (T), and relative humidity (RH) were measured as a function of time. A variety of conditions were tested including the type of wood, age of the pellets, volume of the headspace, humidity, surface/volume ratio, and temperature. An improved kinetic model was developed to predict the CO emission rate. The model assumes that the reaction generating CO is surface-area-limited. The measurements were well-fit by the mathematical model (R2 in the range of 0.93–0.99), suggesting tha...

Long-term measurements of submicrometer aerosol chemistry at the Southern Great Plains (SGP) using an Aerosol Chemical Speciation Monitor (ACSM)

In this study the long-term trends of non-refractory submicrometer aerosol (NR-PM1) composition and mass concentration measured by an Aerosol Chemical Speciation Monitor (ACSM) at the Atmospheric Radiation Measurement (ARM) program's Southern Great Plains (SGP) site are discussed. NR-PM1 data was recorded at ∼30 min intervals over a period of 19 months between November 2010 and June 2012. Positive Matrix Factorization (PMF) was performed on the measured organic mass spectral matrix using a rolling window technique to derive factors associated with distinct sources, evolution processes, and physiochemical properties. The rolling window approach also allows us to capture the dynamic variations of the chemical properties in the organic aerosol (OA) factors over time. Three OA factors were obtained including two oxygenated OA (OOA) factors, differing in degrees of oxidation, and a biomass burning OA (BBOA) factor. Back trajectory analyses were performed to investigate possible sources of major NR-PM1 species at the SGP site. Organics dominated NR-PM1 mass concentration for the majority of the study with the exception of winter, when ammonium nitrate increases due to transport of precursor species from surrounding urban and agricultural areas and also due to cooler temperatures. Sulfate mass concentrations have little seasonal variation with mixed regional and local sources. In the spring BBOA emissions increase and are mainly associated with local fires. Isoprene and carbon monoxide emission rates were obtained by the Model of Emissions of Gases and Aerosols from Nature (MEGAN) and the 2011 U.S. National Emissions Inventory to represent the spatial distribution of biogenic and anthropogenic sources, respectively. The combined spatial distribution of isoprene emissions and air mass trajectories suggest that biogenic emissions from the southeast contribute to SOA formation at the SGP site during the summer.