Biomedical subjects

Steven H Cadle

Publications and source records attributed to Steven H Cadle.

10 recordsLinked to original sources

PubMed2006

Real-world vehicle emissions: A summary of the 15th coordinating research council on-road vehicle emissions workshop.

The Coordinating Research Council held its 15th workshop in April 2005, with nearly 90 presentations describing the most recent mobile source-related emissions research. In this paper, the authors summarize the presentations from researchers who are engaged in improving our understanding of the contribution of mobile sources to air quality. Participants in the workshop discussed emission models and emission inventories, results from gas- and particle-phase emissions studies from spark-ignition and diesel-powered vehicles (with an emphasis in this workshop on particle emissions), effects of fuels on emissions, evaluation of in-use emissions control programs, and efforts to improve our capabilities in performing on-board emissions measurements, as well as topics for future research.

Air Pollutants↗

PubMed2005

Real-world vehicle emissions: a summary of the 14th coordinating research council on-road Vehicle Emissions Workshop.

The Coordinating Research Council held its 14th Vehicle Emissions Workshop in March 2004, where results of the most recent on-road vehicle emissions research were presented. We summarize ongoing work from researchers who are engaged in improving our understanding of the contribution of mobile sources to ambient air quality and emission inventories. Participants in the workshop discussed efforts to improve mobile source emission models, light- and heavy-duty vehicle emissions measurements, on- and off-road emissions measurements, effects of fuels and lubricating oils on emissions, as well as topics for future research.

Air Pollutants↗

PubMed2005

Characterization of carbonaceous species of ambient PM2.5 in Beijing, China.

One-week integrated fine particulate matter (i.e., particles <2.5 microm in diameter; PM2.5) samples were collected continuously with a low-flow rate sampler at a downtown site (Chegongzhuang) and a residential site (Tsinghua University) in Beijing between July 1999 and June 2000. The annual average concentrations of organic carbon (OC) and elemental carbon (EC) at the urban site were 23.9 and 8.8 microg m(-3), much higher than those in some cities with serious air pollution. Similar weekly variations of OC and EC concentrations were found for the two sampling sites with higher concentrations in the winter and autumn. The highest weekly variations of OC and EC occurred in the winter, suggesting that combustion sources for space heating were important contributors to carbonaceous particles, along with a significant impact from variable meteorological conditions. High emissions coupled with unfavorable meteorological conditions led to the max weekly carbonaceous concentration the week of November 18-25, 1999. The weekly mass ratios of OC:EC ranged between 2 and 4 for most samples and averaged 2.9, probably suggesting that secondary OC (SOC) is present most weeks. The range of contemporary carbon fraction, based on the C14 analyses of eight samples collected in 2001, is 0.330-0.479. Estimated SOC accounted for approximately 38% of the total OC at the two sites. Average OC and EC concentrations at Tsinghua University were 25% and 18%, respectively, higher than those at Chegongzhuang, which could be attributed to different local emissions of primary carbonaceous particles and gaseous precursors of SOC, as well as different summer photochemical intensities between the two locations.

Air Pollutants↗

PubMed2004

Characterization of atmospheric mineral components of PM2.5 in Beijing and Shanghai, China.

Weekly PM2.5 samples were collected for one year in Beijing and Shanghai and the crustal elements analyzed to investigate the concentration levels and temporal variations of ambient fine mineral dust. The mass concentrations of Al, Si, Ca, Mg, and Fe exhibited similar significant weekly variations in both Beijing and Shanghai. The annual average PM2.5 concentrations of major crustal elements ranged from 0.27 microg m-3 Mg to 2.48 microg m-3 Si in Beijing, which were 1.40-2.24 times higher than those in Shanghai. Their PM-weighted values were comparable between the two cities. A distinct seasonal pattern was present for these crustal elements with the highest concentrations during the spring in Beijing and during the winter in Shanghai, and the lowest concentrations during the summer in both cities. During the dusty spring of 2000 in Beijing, soil dust was the second most abundant PM2.5 constituent with a contribution as high as 18.6%, over twice that in the winter. The highest fine soil concentration (37.8 microg m-3) and mass percentage (41.6%) occurred in the same week of intensive dust events impacting Beijing. The impact of dust storms complicates the goal of reducing PM2.5 in Beijing. Ca originating from construction activities appears to be a significant PM2.5 contributor as well.

Air Pollutants↗

PubMed2004

Real-world vehicle emissions: a summary of the Thirteenth Coordinating Research Council On-Road Vehicle Emissions Workshop.

The Coordinating Research Council held its thirteenth Vehicle Emissions Workshop in April 2003, when results of the most recent on-road vehicle emissions research were presented. Ongoing work from researchers who are engaged in improving understanding of the contribution of mobile sources to ambient air quality and emission inventories is summarized here. Participants in the workshop discussed efforts to improve mobile source emission models, the role of on-board diagnostic systems in inspection and maintenance programs, light- and heavy-duty vehicle emissions measurements, on- and off-road emissions measurements, effects of fuels and lubricating oils on emissions, as well as topics for future research.

Environmental Monitoring↗

PubMed2004

Innovative methods for emission inventory development and evaluation: workshop summary.

Emission inventories are an essential tool for evaluating, managing, and regulating air pollution. Refinements and innovations in instruments that measure air pollutants, models that calculate emissions, and techniques for data management and uncertainty assessment are needed to enhance emission inventories. This workshop provided recommendations for improving emission factors, improving emission models, and reducing inventory uncertainty. Communication that increases cooperation between developers and users of inventories is essential. Emission inventories that incorporate these improvements will meet the challenges of the future.

Air Pollution↗

PubMed2004

[Characteristics of mineral component in ambient PM2.5 in Beijing].

To understand the concentration levels and temporal variations of the mineral component of PM2.5 in the ambient air of Beijing, weeklong samples were simultaneously collected for one year at Qinghuayuan and Chegongzhuang. The concentrations of five major crustal elements Al, Si, Ca, Mg, and Fe exhibited similar significant weekly variations, with their maximum values in the week of a serious dust event in the spring of 2000. Obvious seasonal pattern was also found for these elements, indicating different influences on fine mineral particles from the source emissions and meteorology in different seasons. Soil dust concentration increased from a low level in summer to the peak value (21.1 microg x m(-3)) in spring, suggesting that frequent dust events made a significant contribution to fine soil dust. A large number of construction activities in Beijing substantially increased the loading of fine calcium-bearing particles, and their emissions thus need to be further controlled.

Air Pollutants↗

PubMed2003

Real-world vehicle emissions: a summary of the twelfth Coordinating Research Council On-Road Vehicle Emissions Workshop.

The Coordinating Research Council (CRC) held its 12th workshop in April 2002, with nearly 90 presentations on the most recent on-road vehicle emissions research. This paper summarizes the presentations from researchers who are engaged in improving understanding of the contribution of mobile sources to air quality. Participants in the workshop discussed mobile source emission models and emission inventories, results from gas- and particle-phase emissions studies from spark-ignition and diesel-powered vehicles (with an emphasis in this workshop on particle emissions), effects of fuels on emissions, evaluation of in-use emissions control programs, and efforts to improve our capabilities in performing on-board emissions measurements, as well as topics for future research.

Air Pollution↗

PubMed2003

[Characteristics and sources of trace elements in ambient PM2.5 in Beijing].

To understand concentration levels and sources of trace elements in PM2.5(particulate matter with aerodynamic diameters less than 2.5 microns) concentration and composition in the ambient air of Beijing, weekly samples were simultaneously collected for one year in Chegongzhuang and Qinghuayuan. Trace elements exhibited similar significant weekly variations. The strongest weekly shift occurred in winter, which reached as high as a factor of 1.6 for two consecutive weeks. No obvious seasonal pattern was found for trace elements except for that their average concentrations were much higher in winter. The EFs of trace elements were lowest in spring, probably due to frequent dust storms resulting in reduced contribution of anthropogenic sources and increased contribution of soil dust. The ambient concentrations of Se, Br, and Pb were about 1000-8000 times higher than those expected from the crustal soil in Beijing. Se was most enriched in PM2.5, reflecting the characteristics of fine particles from coal burning in Beijing. The annual mean concentration of Pb of 0.31 microgram.m-3 did not exceeded the WHO annual standard, but was at very high level compared to those measured in Los Angles and Brisbane. Comparison analysis of Pb with Br and Se shows that coal burning is probably another major source of Pb in PM2.5 other than vehicle emission.

Air↗

PubMed2002

Real-world vehicle emissions: a summary of the Eleventh Coordinating Research Council On-Road Vehicle Emissions Workshop.

The Coordinating Research Council (CRC) held its eleventh workshop in March 2001, focusing on results from the most recent real-world vehicle emissions research. We summarize the presentations from researchers engaged in improving our understanding of the contribution of mobile sources to ambient air quality and emission inventories. Participants in the workshop discussed efforts to improve mobile source emission models and emission inventories, the role of on-board diagnostic (OBD) systems in inspection and maintenance (I/M) programs, particulate matter (PM) emissions, contributions of diesel vehicles to the emission inventory, on-road emissions measurements, fuel effects, unregulated emissions, and microscale and modal emission models, as well as topics for future research.

Air Pollution↗