Variability in the primary emissions and secondary gas and particle formation from vehicles using bioethanol mixtures

Bioethanol for use in vehicles is becoming a substantial part of global energy infrastructure because it is renewable and some emissions are reduced. Carbon monoxide (CO) emissions and total hydrocarbons (THC) are reduced, but there is still controversy regarding emissions of nitrogen oxides (NO_x), aldehydes, and ethanol; this may be a concern because all these compounds are precursors of ozone and secondary organic aerosol (SOA). The amount of emissions depends on the ethanol content, but it also may depend on the engine quality and ethanol origin. Thus, a photochemical chamber was used to study secondary gas and aerosol formation from two flex-fueled vehicles using different ethanol blends in gasoline. One vehicle and the fuel used were made in the United States, and the others were made in Brazil. Primary emissions of THC, CO, carbon dioxide (CO₂), and nonmethane hydrocarbons (NMHC) from both vehicles decreased as the amount of ethanol in gasoline increased. NO_x emissions in the U.S. and Brazilian cars decreased with ethanol content. However, emissions of THC, CO, and NO_x from the Brazilian car were markedly higher than those from the U.S. car, showing high variability between vehicle technologies. In the Brazilian car, formation of secondary nitrogen dioxide (NO₂) and ozone (O₃) was lower for higher ethanol content in the fuel. In the U.S. car, NO₂ and O₃ had a small increase. Secondary particle (particulate matter [PM]) formation in the chamber decreased for both vehicles as the fraction of ethanol in fuel increased, consistent with previous studies. Secondary to primary PM ratios for pure gasoline is 11, also consistent with previous studies. In addition, the time required to form secondary PM is longer for higher ethanol blends. These results indicate that using higher ethanol blends may have a positive impact on air quality.

IMPLICATIONS

The use of bioethanol can significantly reduce petroleum use and greenhouse gas emissions worldwide. Given the extent of its use, it is important to understand its effect on urban pollution. There is a controversy on whether there is a reduction or increase in PM emission when using ethanol blends. Primary emissions of THC, CO, CO₂, NO_x, and NMHC for both cars decreased as the fraction of ethanol in gasoline increased. Using a photochemical chamber, the authors have found a decrease in the formation of secondary particles and the time required to form secondary PM is longer when using higher ethanol blends.

Particle size distribution and its relationship to black carbon in two urban and one rural site in Santiago de Chile

The size distribution of particles has been studied in three sites in the Metropolitan area of Santiago de Chile in the winter of 2009 and a comparison with black carbon was performed. Two sites are located near busy streets in Santiago and the other site is located in a rural area about 40 km west of Santiago with little influence from vehicles, but large influence from wood burning. The campaign lasted 1 or 2 weeks in each site. We have divided the particle size measurements into four groups (10-39 nm, 40-62 nm, 63-174 nm, and 175-700 nm) in order to compare with the carbon monitor. In the sites near the street, black carbon has a high correlation (R = 0.85) with larger particles (175-700 nm). The correlation decreased when black carbon was compared with smaller particles, having very small correlation with the smallest sizes (10-39 nm). In the rural site, black carbon also has a high correlation (R = 0.86) with larger particles (175-700 nm), but the correlation between black carbon and the finest particles (10-39 nm) decreases to near 0. These measurements are an indication that wood burning does not generate particles smaller than -50 nm. In the urban sites, particle size distribution is peaked toward smaller particles (10-39 nm) only during rush hours, but at other times, particles size distribution is peaked toward larger sizes. When solar radiation was high, evidence of secondary particle formation was seen in the rural site, but not in the urban sites. The correlation between the number of secondary particles and solar radiation was R2 = 0.46, indicating that it there may be other variables that play a role in ultrafine particle formation. Implications: A study of the size distribution of particles and black carbon concentration in two street sites and one rural site shows that in the last site the number of particles ultrafine particles (d < 40 nm) is 10 times lower but the number of larger particles is about 2 times lower. Thus, the rural site has less of the particles that are more dangerous to health. The number ofultrafine particles is mostly associated with traffic, while the number of larger particles is associated with wood burning and other sources. Wood burning does not generate particles smaller than -50 nm.

[The National Programme for Disease Management Guidelines. Goals, contents, patient involvement]

The Programme for National Disease Management Guidelines (German DM-CPG Programme) aims at the implementation of best practice recommendations for prevention, acute care, rehabilitation and chronic care. The programme, focussing on high priority healthcare topics, has been sponsored since 2003 by the German Medical Association (BAEK), the Association of the Scientific Medical Societies (AWMF), and by the National Association of Statutory Health Insurance Physicians (KBV). It is organised by the German Agency for Quality in Medicine, a founding member of the Guidelines International Network (G-I-N). The main objective of the programme is to establish consensus of the medical professions on evidence-based key recommendations covering all sectors of health care provision and facilitating the coordination of care for the individual patient through time and across disciplines. Within this framework experts from national patient self-help groups have been developing patient guidance based upon the recommendations for healthcare providers. The article describes goals, topics and selected contents of the DM-CPG programme - using asthma as an example.

[Glossary on patient safety -- a contribution to on-target-definition and to appreciate the subjects of "patient safety"]

Since the release of the report "To Err is Human" by the American Institute of Medicine (IOM) the subject "Medical Risks, Errors and Patient Safety" has gained increasing interest in literature. In Germany, neither extensive statistics nor generally significant epidemiological studies regarding common errors associated with damages caused to patients' health exist. In recent years the subject has become increasingly interesting both in specialist discussion and it the lay press; it has become evident that the different use of terms, especially those originating from the Anglo-Saxon language, can lead to misunderstandings. Hence, as one of the first steps of its action programme, the expert panel "Patient Safety" of the German Agency for Quality in Medicine has compiled a glossary of technical terms to provide adequate support to the discussion this important subject of nomenclature.

[The German Quality Management System for Outpatient Care (Q-M-A) Checklist--an instrument for assessing quality management systems in outpatient care]

Quality management systems had originally been designed for industrial purposes and were hardly applicable for small enterprises, there have been adjustments to the two main applications EFQM and ISO enabling utilisation also in ambulatory care. There are also different approaches like the Dutch Visitatiae concept which reflects the needs of GP's and is based on peer exchange. The presented paper gives an overview of existing quality management and certification systems and presents an instrument for evaluation. This checklist was developed by an interdisciplinary expert panel of the Agency for Quality in Medicine and serves as an aid for users and graders of quality management systems with regard to the feasibility of these systems.

Traffic and seasonal dependence of the light absorption coefficient in santiago de chile

We have designed and built a compact, low-cost automated system to measure the optical absorption coefficient of air. Because most of the light absorption is due to black carbon, this method is a direct measure of the amount of black carbon in the atmosphere. The equipment was used to measure absorption over a period of one year in a central area of Santiago. Our results show a strong correlation with the daily traffic pattern. The highest value of the absorption coefficient during most of the year occurs during the morning rush hour (0700-0800), and the lowest value either early in the morning (0300-0500) or in the afternoon (1400-1700). The absorption coefficient also shows a strong dependence with the season of the year, with values 10-20 times higher in winter than in summer. The data show that, during most of the year, the amount of black carbon present in the atmosphere is due to traffic. At night, during winter, the high concentration of black carbon is due to the temperature inversion effect.

Large-area avalanche photodiodes for the detection of soft x rays

The charge-collection efficiency of beveled-edge-type silicon avalanche photodiodes has been determined for soft x rays in the 50-300-eV range. An efficiency of greater than 80% is measured for energies below the Si L absorption edge. The measured efficiency is well described by a model that accounts for absorption in an oxide overlayer and recombination at the front surface of the diode. The avalanche photodiodes are shown to be significantly more sensitive compared with other detectors for pulsed sources such as a laser-produced plasma source. These results are also very encouraging for soft-xray/ extreme-UV applications involving synchrotron radiation.