Advanced Emission Control Technologies Research Articles

Effect of Fuel Quality, Vehicle Maintenance and Advanced Emission Control Technology on Pakistan In -Use Light Vehicle Emissions

Pakistan is suffering from some of the worst air quality in Asia. The transportation sector is a major contributor to air pollution along diesel powered vehicles and rickshaws being the primary pollutions source. However, the contribution from light duty vehicles cannot be ignored. In this paper, results from an in-use emission study of over 500 light duty vehicles are reported and discussed. A random geographically diversified survey is conducted to collect data regarding the emissions from in-use vehicles in Pakistan. A review of the government fuel quality policy is provided. Through this analysis, the effects of polices addressing vehicle maintenance and repair, advanced vehicle emission technology and fuel quality are evaluated. These results provide insight to guide further measures to ensure meaningful impact on urban air quality in Pakistan. The same study may also be conducted in other regional countries to support effective emission control policy from the light vehicles.

Advanced Emission Controls and E-fuels on a Gasoline Car for Zero-Impact Emissions

<div class="section abstract"><div class="htmlview paragraph">The electrified internal combustion engine can contribute to further improving air quality and reducing impact on climate change. A previous publication looked into ultra-low initial cold-start emissions with the implementation of a state-of-the-art emission control system on a gasoline vehicle with market E10 gasoline. This paper reports additional investigations on different drop-in sustainable renewable fuels, including e-fuels. The gasoline demonstrator vehicle is equipped with a 48V mild-hybrid powertrain with a 1.5 L direct injection engine. The innovative emission control system consists of an electrically pre-heated catalyst (EHC) and first three-way catalyst (TWC) in close-coupled position, in combination with an underfloor catalysed gasoline particulate filter (cGPF), second TWC and ammonia slip catalyst (ASC). Pollutant emission tests are conducted on a challenging chassis dyno test for cold-start emissions at 23 °C and -10 °C. Tests that were done before on reference E10 fuel are repeated on Blue Gasoline and two e-gasoline fuels. Similar ultra-low pollutant emissions are measured on the sustainable renewable fuels compared to the reference E10. A Well-to-Wheel analysis is conducted to investigate the potential to reduce CO<sub>2</sub> emissions. The analysis follows the methodology of the JEC report v5 (JRC-EUCAR-Concawe). The results show that already significant reduction is possible today with Blue Gasoline. The e-gasoline shows potential for near-zero CO<sub>2</sub> emissions. With the combination, of advanced emission control technologies and sustainable renewable fuels, research is evolving towards reaching zero-impact emissions for both air quality and climate change.</div></div>

Advanced Emission Controls and Sustainable Renewable Fuels for Low Pollutant and CO2 Emissions on a Diesel Passenger Car

Research efforts into advanced emission control systems led to significant reduction of pollutant emissions of modern internal combustion engines. Sustainable renewable fuels are used to further reduce their Well-to-Wheels greenhouse gas emissions. The novel aspect of this paper is the compatibility investigation of existing advanced emission control technologies for achieving low pollutant emissions with the use of sustainable renewable fuels with vehicle tests. This is done on a diesel demonstrator vehicle, equipped with Lean NOx trap and dual-SCR technologies in combination with a 48V mild-hybrid powertrain. Tailpipe pollutant and CO2 emissions are measured for market diesel fuel with 7% renewable fatty-acid-methyl-ester (FAME) (B7), diesel fuel with 30% FAME (B30), and 100% renewable hydrotreated vegetable oil (HVO). Results show no significant difference in pollutant emissions between the different fuels used. In a second part of the study, a Well-to-Wheels (WTW) analysis is conducted. This includes different pathways for the biomass-to-liquid fuels that were tested on the vehicle, as well as a power-to-diesel (e-diesel) assessment. Results show that significant WTW CO2 reductions are possibly compared to the state-of-the-art market diesel fuel. Part of this reduction is already possible for the existing fleet as most of paraffinic compounds are drop-in for market diesel fuel.

Trends in air pollutant emissions from the sintering process of the iron and steel industry in the Fenwei Plain and surrounding regions in China, 2014–2017

China is the largest iron and steel producer and consumer in the world. The iron and steel manufacture, especially the sintering process, is energy-intensive, and contributes substantially to air pollutant emissions in China. Compared with other regions, the Fenwei Plain, a coal base, has a heavy industry concentration, and high pollutant emission total amount. In addition, urban air pollution has rebounded, and the pollutants concentrations in many cities have increased rather than decreased. In this study, we investigated the inter-annual trends of particulate matter (PM), sulfur dioxide (SO2) and nitrogen oxide (NOx) from the sintering process of iron and steel industry (ISI) in the Fenwei Plain and the surrounding regions in China from 2014 to 2017 based on the Continuous Emission Monitoring System (CEMS). We found that the oxygen content of the flue gas is the key to judge whether the sintering flue gas air pollutant emission concentration can meet the standard. Therefore, we adopted the converted concentration by the reference oxygen content in the final analysis. Overall, the SO2 and PM emission concentrations exhibit a downward trend from 2014 to 2017, in response to the strengthening of the emission control policies and standards in the ISI, whereas the NOx emission concentration did not change significantly during the same period The emission factors (EFs) of PM, NOx and SO2 obtained in this study are lower than previous estimates. In 2017, the SO2 and PM emissions were 27% and 32% lower than the levels in 2014.While NOx was 22% higher than the level in 2014. Our study confirmed the effectiveness of current emission control policies and standards in the iron and steel sector. However, the levels of NOx emissions were still high until 2017, illustrating the urgent need for more advanced emission control technologies to further reduce NOx emissions from the sintering flue gas in China.

Numerical Simulation of NOx Reduction in a SCR System

The stringent limits of emission standards require advanced emission control technologies to be used in modern on and off highway diesel engines. They include both in-cylinder and aftertreatment measures where the latter now have become almost mandatory. Selective catalytic reduction aftertreatment systems are widely used for nitrogen oxide (NOX) conversion in exhaust gases into harmless N2. To reduce time and costs, at the design stage of SCR systems numerical modelling is applied. Mathematical models and methods providing high prediction accuracy with and acceptable level of computational efforts are required. In this work an approach for complete simulation of SCR systems based on the coupling of commercial CFD software with developed multichannel 1D catalyst model is presented. The first one is used to carefully describe processes occurring upstream in the catalytic converter, particularly, during urea water solution injection and flow mixing. As a result, the distributions of flow parameters at catalyst inlet are derived. They are subsequently imported as boundary conditions into a developed multichannel catalyst model that allows one to take them into account when calculating NOx conversion efficiency. Based on the proposed approach a SCR system was simulated. The effect of non-uniform distributions of NH3 concentration and the gas flow velocity at the catalyst inlet on its performance was investigated. It has been shown that they have a great impact on NOX conversion and should be taken into account during the catalyst modelling.

HISTORICAL EMISSIONS AND FUTURE MITIGATION OF PRIMARY AIR POLLUTANTS FROM INDUSTRIAL BOILER IN CHINA

Industrial boilers are recognized as a significant anthropogenic emission source of primary air pollutants in China. By using specific and detailed statistical data and comprehensive time-varying dynamic emission factors (EFs), we calculated the temporal-spatial emission characteristics of total suspended particulate (TSP), SO2 and NOx from industrial boilers during 1980 to 2016 for the first time. Further emission trends from 2016 to 2030 were also forecasted based on the current atmospheric action policy. Our results showed a generally decreasing trend of the annual EFs for TSP, SO2 and NOx due to implementation of stricter local emission standards, application of advanced emission control technologies, and elimination of small and inefficient boilers. In 2016, national TSP, SO2 and NOx emissions from industrial boilers were estimated at 5.43, 6.99 and 2.47 million tons (Mt), respectively. The higher emissions of primary air pollutants from coal-fired industrial boilers (CFIBs) were concentrated in northeast and eastern China, while NOx emissions from gas-fired industrial boilers (GFIBs) were mainly concentrated in the Beijing-Tianjin-Hebei region and its surrounding areas. Under a series of current action plans, it would be successful in abating emissions of TSP, SO2 and NOx by 95%, 94% and 71% in the year of 2030. More attention should be paid to the whole process control of industrial boilers in the future polices making, such as introducing clean fuels for persistent emission reduction at source, strengthening the operation, maintenance and management of pollution control technologies to ensure the best control effect.

Analysis of spray dynamics of urea–water-solution jets in a SCR-DeNOx system: An LES based study

Among various advanced emission control technologies used to reduce NOx emission from diesel engines, the selective catalytic reduction (SCR) technique has proven to be more efficient. However, it is still facing the improvement of low temperature performance and the avoidance of urea deposit formation due to complex spray–wall interaction process.To gain more deep understanding of these processes, a spray module is developed for the first time within a full LES framework based on an Eulerian–Lagrangian approach. It includes especially (1) a primary and a secondary breakup model along with an advanced collision model, both to account for the atomization generated close to the nozzle exit by the multi-hole circular orifice injector used and (2) a multi-component droplet evaporation model along with a two-way coupling between the carrier gaseous phase and the droplet liquid phase throughout the dilute spray region.The suggested model is applied to evaluate the dynamics of the multi-component droplets spray resulting from an adBlue injection into a hot gas cross flow inside a channel mimicking a SCR-DeNOx flow system. First, an assessment of the multi-component droplet evaporation under hot stagnant gas environment is made. Second, the results of the adBlue spray/gas phase cross flow interaction are reported in terms of comparison between experimental data (spray structure, spray angle and penetration depth, droplet size distribution and velocity) with numerical simulations. It turns out that the model designed is able to capture in a satisfactory way the spray properties in a SCR like system.

Measurement of area and personal breathing zone concentrations of diesel particulate matter (DPM) during oil and gas extraction operations, including hydraulic fracturing

ABSTRACTDiesel engines serve many purposes in modern oil and gas extraction activities. Diesel particulate matter (DPM) emitted from diesel engines is a complex aerosol that may cause adverse health effects depending on exposure dose and duration. This study reports on personal breathing zone (PBZ) and area measurements for DPM (expressed as elemental carbon) during oil and gas extraction operations including drilling, completions (which includes hydraulic fracturing), and servicing work.Researchers at the National Institute for Occupational Safety and Health (NIOSH) collected 104 full-shift air samples (49 PBZ and 55 area) in Colorado, North Dakota, Texas, and New Mexico during a four-year period from 2008–2012. The arithmetic mean (AM) of the full shift TWA PBZ samples was 10 µg/m3; measurements ranged from 0.1–52 µg/m3. The geometric mean (GM) for the PBZ samples was 7 µg/m3. The AM of the TWA area measurements was 17 µg/m3 and ranged from 0.1–68 µg/m3. The GM for the area measurements was 9.5 µg/m3. Differences between the GMs of the PBZ samples and area samples were not statistically different (P > 0.05).Neither the Occupational Safety and Health Administration (OSHA), NIOSH, nor the American Conference of Governmental Industrial Hygienists (ACGIH) have established occupational exposure limits (OEL) for DPM. However, the State of California, Department of Health Services lists a time-weighted average (TWA) OEL for DPM as elemental carbon (EC) exposure of 20 µg/m3. Five of 49 (10.2%) PBZ TWA measurements exceeded the 20 µg/m3 EC criterion. These measurements were collected on Sandmover and Transfer Belt (T-belt) Operators, Blender and Chemical Truck Operators, and Water Transfer Operators during hydraulic fracturing operations.Recommendations to minimize DPM exposures include elimination (locating diesel-driven pumps away from well sites), substitution, (use of alternative fuels), engineering controls using advanced emission control technologies, administrative controls (configuration of well sites), hazard communication, and worker training.

NOx emissions from Euro IV busses with SCR systems associated with urban, suburban and freeway driving patterns

NOx and particulate matter (PM) emissions from heavy-duty diesel vehicles (HDVs) have become the most important sources of pollutants affecting urban air quality in China. In recent years, a series of emission control strategies and diesel engine polices have been introduced that require advanced emission control technology. China and Europe mostly have used Selective Catalytic Reduction (SCR) with urea to meet the Euro IV diesel engine emission standard. In this study, two Euro IV busses with SCR were tested by using potable emission measurement system (PEMS) to assess NOx emissions associated with urban, suburban and freeway driving patterns. The results indicated that with the SCR system, the urea injection time for the entire driving period increased with higher vehicle speed. For freeway driving, the urea injection time covered 71%–83% of the driving period; the NOx emission factors from freeway driving were lower than those associated with urban and suburban driving. Unfortunately, the NOx emission factors were 2.6–2.8-, 2.3–2.7- and 2.2–2.3-fold higher than the Euro IV standard limits for urban, suburban and freeway driving, respectively; NOx emission factors (in g/km and g/(kW·h)) from the original vehicles (without SCR) were higher than their corresponding vehicles with SCR for suburban and freeway driving. Compared with the IVE model results, the measured NOx emission factors were 1.60–1.16-, 1.77–1.27-, 2.49–2.44-fold higher than the NOx predicted by the IVE model for urban and suburban driving, respectively. Thus, an adjustment of emission factors is needed to improve the estimation of Euro IV vehicle emissions in China.

Linking induced technological change, and environmental regulation: Evidence from patenting in the U.S. auto industry

This article uses a carefully screened patent database in automobile emission control technologies and a detailed regulatory action analysis to examine firms’ innovation in response to U.S. technology-forcing auto emissions standards enacted between 1970 and 1998. The study finds that under the performance-based technology-forcing (PBTF) auto emissions regulations, both automakers and component suppliers innovated and introduced more advanced emission control technologies for automobile applications. The study also shows that stringent PBTF regulation temporarily induced domestic U.S. firms to become more innovative than foreign firms that operated in the local U.S. market during the early phase of the regulatory regime. Findings of this research strongly imply that government intervention in the form of technology-forcing regulation can drive firms to invest in technological innovation.

Environmental accountability for a sustainable Earth

In the present state of the world, the space age, human beings who are the trustees of the earth have a duty to bequeath a clean mother earth to nurture all living beings. We must rally and inspire a grand effort for earth, and an earth campaign that will eliminate poverty and pollution and bring new freedom, order and opportunity. Climate is changing due to human activity. Unless we act now, our children will inherit a hotter world, dirtier air and water, more severe floods and droughts and more wildfires. Potential increase of about 2.5 to 10 degrees Fahrenheit per year is observed. Air pollution affects everyone. Motor vehicle pollution has been substantially reduced with the help of advanced emission control technologies. A common approach to continuous improvement is needed to build a sustainable earth. Keywords: Global warming, green house effect, climate change, thermal equilibrium, acid rain, carbon off-set, energy.

Establishment of a database of emission factors for atmospheric pollutants from Chinese coal-fired power plants

Field measurements and data investigations were conducted for developing an emission factor database for inventories of atmospheric pollutants from Chinese coal-fired power plants. Gaseous pollutants and particulate matter (PM) of different size fractions were measured using a gas analyzer and an electric low-pressure impactor (ELPI), respectively, for ten units in eight coal-fired power plants across the country. Combining results of field tests and literature surveys, emission factors with 95% confidence intervals (CIs) were calculated by boiler type, fuel quality, and emission control devices using bootstrap and Monte Carlo simulations. The emission factor of uncontrolled SO 2 from pulverized combustion (PC) boilers burning bituminous or anthracite coal was estimated to be 18.0S kg t −1 (i.e., 18.0 × the percentage sulfur content of coal, S) with a 95% CI of 17.2S–18.5S. NO X emission factors for pulverized-coal boilers ranged from 4.0 to 11.2 kg t −1, with uncertainties of 14–45% for different unit types. The emission factors of uncontrolled PM 2.5, PM 10, and total PM emitted by PC boilers were estimated to be 0.4A (where A is the percentage ash content of coal), 1.5A and 6.9A kg t −1, respectively, with 95% CIs of 0.3A–0.5A, 1.1A–1.9A and 5.8A–7.9A. The analogous PM values for emissions with electrostatic precipitator (ESP) controls were 0.032A (95% CI: 0.021A–0.046A), 0.065A (0.039A–0.092A) and 0.094A (0.0656A–0.132A) kg t −1, and 0.0147A (0.0092–0.0225A), 0.0210A (0.0129A–0.0317A), and 0.0231A (0.0142A–0.0348A) for those with both ESP and wet flue-gas desulfurization (wet-FGD). SO 2 and NO X emission factors for Chinese power plants were smaller than those of U.S. EPA AP-42 database, due mainly to lower heating values of coals in China. PM emission factors for units with ESP, however, were generally larger than AP-42 values, because of poorer removal efficiencies of Chinese dust collectors. For units with advanced emission control technologies, more field measurements are needed to reduce emission factor uncertainties.

Characterization of Particle Bound Organic Carbon from Diesel Vehicles Equipped with Advanced Emission Control Technologies

A chassis dynamometer study was carried out by the University of Southern California in collaboration with the Air Resources Board (CARB) to investigate the physical, chemical, and toxicological characteristics of diesel emissions of particulate matter (PM) from heavy-duty vehicles. These heavy-duty diesel vehicles (HDDV) were equipped with advanced emission control technologies, designed to meet CARB retrofit regulations. A HDDV without any emission control devices was used as the baseline vehicle. Three advanced emission control technologies; continuously regenerating technology (CRT), zeolite- and vanadium-based selective catalytic reduction technologies (Z-SCRT and V-SCRT), were tested under transient (UDDS) (1) and cruise (80 kmph) driving cycles to simulate real-world driving conditions. This paper focuses on the characterization of the particle bound organic species from the vehicle exhaust. Physical and chemical properties of PM emissions have been reported by Biswas et al. Atmos. Environ. 2008, 42, 5622-5634) and Hu et al. (Atmos. Environ. 2008, submitted) Significant reductions in the emission factors (microg/mile) of particle bound organic compounds were observed in HDDV equipped with advanced emission control technologies. V-SCRT and Z-SCRT effectively reduced PAHs, hopanes and steranes, n-alkanes and acids by more than 99%, and often to levels below detection limits for both cruise and UDDS cycles. The CRT technology also showed similar reductions with SCRT for medium and high molecular weight PAHs, acids, but with slightly lower removal efficiencies for other organic compounds. Ratios of particle bound organics-to-OC mass (microg/g) from the baseline exhaust were compared with their respective ratios in diesel fuel and lubricating oil, which revealed that hopanes and steranes originate from lubricating oil, whereas PAHs can either form during the combustion process or originate from diesel fuel itself. With the introduction of emission control technologies, the particle bound organics-to-OC ratios (microg/g) decreased considerably for PAHs, while the reduction was insignificant for hopanes and steranes, implying that fuel and lubricating oil have substantially different contributions to the total OC emitted by vehicles operating with after-treatment control devices compared to the baseline vehicle since these control technologies had a much larger impact on PAH OC than hopanes and steranes OC.

Chemical speciation of PM emissions from heavy-duty diesel vehicles equipped with diesel particulate filter (DPF) and selective catalytic reduction (SCR) retrofits

Four heavy-duty diesel vehicles (HDDVs) in six retrofitted configurations (CRT ®, V-SCRT ®, Z-SCRT ®, Horizon, DPX and CCRT ®) and a baseline vehicle operating without after--treatment were tested under cruise (50 mph), transient UDDS and idle driving modes. As a continuation of the work by Biswas et al. [Biswas, S., Hu, S., Verma, V., Herner, J., Robertson, W.J., Ayala, A., Sioutas, C., 2008. Physical properties of particulate matter (PM) from late model heavy-duty diesel vehicles operating with advanced emission control technologies. Atmospheric Environment 42, 5622–5634.] on particle physical parameters, this paper focuses on PM chemical characteristics (Total carbon [TC], Elemental carbon [EC], Organic Carbon [OC], ions and water-soluble organic carbon [WSOC]) for cruise and UDDS cycles only. Size-resolved PM collected by MOUDI–Nano-MOUDI was analyzed for TC, EC and OC and ions (such as sulfate, nitrate, ammonium, potassium, sodium and phosphate), while Teflon coated glass fiber filters from a high volume sampler were extracted to determine WSOC. The introduction of retrofits reduced PM mass emissions over 90% in cruise and 95% in UDDS. Similarly, significant reductions in the emission of major chemical constituents (TC, OC and EC) were achieved. Sulfate dominated PM composition in vehicle configurations (V-SCRT ®-UDDS, Z-SCRT ®-Cruise, CRT ® and DPX) with considerable nucleation mode and TC was predominant for configurations with less (Z-SCRT ®-UDDS) or insignificant (CCRT ®, Horizon) nucleation. The transient operation increases EC emissions, consistent with its higher accumulation PM mode content. In general, solubility of organic carbon is higher (average ∼5 times) for retrofitted vehicles than the baseline vehicle. The retrofitted vehicles with catalyzed filters (DPX, CCRT ®) had decreased OC solubility (WSOC/OC: 8–25%) unlike those with uncatalyzed filters (SCRT ®s, Horizon; WSOC/OC ∼ 60–100%). Ammonium was present predominantly in the nucleation mode, indicating that ternary nucleation may be the responsible mechanism for formation of these particles.

On-road emissions from urban buses with SCR + Urea and EGR + DPF systems using diesel and biodiesel

Due to growing concerns about NO x and particulate matter (PM) emissions from diesel engines, stricter regulations are being introduced requiring advanced emission control technology. In response the diesel industry has begun testing various emission control technologies and applying them. To assess vehicle renewal policies of bus companies, two exhaust after-treatment technologies are compared: the combination of a diesel particulate filter and an exhaust gas re-circulation system and the combination of a selective catalytic reduction and urea. On-board emission measurements were conducted under real-world driving conditions on a specific bus route in the city of Madrid.

Physical properties of particulate matter (PM) from late model heavy-duty diesel vehicles operating with advanced PM and NO x emission control technologies

Emission control technologies designed to meet the 2007 and 2010 emission standards for heavy-duty diesel vehicles (HDDV) remove effectively the non-volatile fraction of particles, but are comparatively less efficient at controlling the semi-volatile components. A collaborative study between the California Air Resources Board (CARB) and the University of Southern California was initiated to investigate the physicochemical and toxicological characteristics of the semi-volatile and non-volatile particulate matter (PM) fractions from HDDV emissions. This paper reports the physical properties, including size distribution, volatility (in terms of number and mass), surface diameter, and agglomeration of particles emitted from HDDV retrofitted with advanced emission control devices. Four vehicles in combination with six after-treatment devices (V-SCRT ®, Z-SCRT ®, CRT ®, DPX, Hybrid-CCRT ®, EPF) were tested under three driving cycles: steady state (cruise), transient (urban dynamometer driving schedule, UDDS), and idle. An HDDV without any control device is served as the baseline vehicle. Substantial reduction of PM mass emissions (>90%) was accomplished for the HDDV operating with advanced emission control technologies. This reduction was not observed for particle number concentrations under cruise conditions, with the exceptions of the Hybrid-CCRT ® and EPF vehicles, which were efficient in controlling both—mass and number emissions. In general, significant nucleation mode particles (<50 nm) were formed during cruise cycles in comparison with the UDDS cycles, which emit higher PM mass in the accumulation mode. The nucleation mode particles (<50 nm) were mainly internally mixed, and evaporated considerably between 150 and 230 °C. Compared to the baseline vehicle, particles from vehicles with controls (except of the Hybrid-CCRT ®) had a higher mass specific surface area.

Real-time characterization of particle-bound polycyclic aromatic hydrocarbons in ambient aerosols and from motor-vehicle exhaust

Abstract. A photo-electric aerosol sensor, a diffusion charger, an Aethalometer, and a continuous particle counter were used along with other real-time instruments to characterize the particle-bound polycyclic aromatic hydrocarbon (p-PAH) content, and the physical/chemical characteristics of aerosols collected a) in Wilmington (CA) near the Los Angeles port and close to 2 major freeways, and b) at a dynamometer testing facility in downtown Los Angeles (CA), where 3 diesel trucks were tested. In Wilmington, the p-PAH, surface area, particle number, and "black" carbon concentrations were 4-8 times higher at 09:00–11:00 a.m. than between 17:00 and 18:00 p.m., suggesting that during rush hour traffic people living in that area are exposed to a higher number of diesel combustion particles enriched in p-PAH coatings. Dynamometer tests revealed that the p-PAH emissions from the "baseline" truck (no catalytic converter) were up to 200 times higher than those from the 2 vehicles equipped with advanced emission control technologies, and increased when the truck was accelerating. In Wilmington, integrated filter samples were collected and analyzed to determine the concentrations of the most abundant p-PAHs. A correlation between the total p-PAH concentration (μg/m3) and the measured photo-electric aerosol sensor signal (fA) was also established. Estimated ambient p-PAH concentrations (Average=0.64 ng/m3; Standard deviation=0.46 ng/m3 were in good agreement with those reported in previous studies conducted in Los Angeles during a similar time period. Finally, we calculated the approximate theoretical lifetime (70 years per 24-h/day) lung-cancer risk in the Wilmington area due to inhalation of multi-component p-PAHs and "black" carbon. Our results indicate that the lung-cancer risk is highest during rush hour traffic and lowest in the afternoon, and that the genotoxic risk of the considered p-PAHs does not seem to contribute to a significant part of the total lung-cancer risk attributable to "black" carbon.

Scenarios of global anthropogenic emissions of air pollutants and methane until 2030

We have used a global version of the Regional Air Pollution Information and Simulation (RAINS) model to estimate anthropogenic emissions of the air pollution precursors sulphur dioxide (SO 2), nitrogen oxides (NO x ), carbon monoxide (CO), primary carbonaceous particles of black carbon (BC), organic carbon (OC) and methane (CH 4). We developed two scenarios to constrain the possible range of future emissions. As a baseline, we investigated the future emission levels that would result from the implementation of the already adopted emission control legislation in each country, based on the current national expectations of economic development. Alternatively, we explored the lowest emission levels that could be achieved with the most advanced emission control technologies that are on the market today. This paper describes data sources and our assumptions on activity data, emission factors and the penetration of pollution control measures. We estimate that, with current expectations on future economic development and with the present air quality legislation, global anthropogenic emissions of SO 2 and NO x would slightly decrease between 2000 and 2030. For carbonaceous particles and CO, reductions between 20% and 35% are computed, while for CH 4 an increase of about 50% is calculated. Full application of currently available emission control technologies, however, could achieve substantially lower emissions levels, with decreases up to 30% for CH 4, 40% for CO and BC, and nearly 80% for SO 2.

Future US Motor Vehicle Emission Standards and the Role of Advanced Emission Control Technology in Meeting Those Standards

Future emission standards applicable to diesel- and gasoline-powered vehicles and engines are reviewed. The important role of advanced catalyst technology to meet these new standards is discussed and progress reported.