Detection of Greenhouse Gas Precursors from Diesel Engines Using Electrochemical and Photoacoustic Sensors

Atmospheric pollution is one of the worst threats to modern society. The consequences derived from different forms of atmospheric pollution vary from the local to the global scale, with deep impacts on climate, environment and human health. Several gaseous pollutants, even when present in trace concentrations, play a fundamental role in important processes that occur in atmosphere. Phenomena such as global warming, photochemical smog formation, acid rain and the depletion of the stratospheric ozone layer are strongly related to the increased concentration of certain gaseous species in the atmosphere. The transport sector significantly produces atmospheric pollution, mainly when diesel oil is used as fuel. Therefore, new methodologies based on selective and sensitive gas detection schemes must be developed in order to detect and monitor pollutant gases from this source. In this work, CO2 Laser Photoacoustic Spectroscopy was used to evaluate ethylene emissions and electrochemical analyzers were used to evaluate the emissions of CO, NOx and SO2 from the exhaust of diesel powered vehicles (rural diesel with 5% of biodiesel, in this paper called only diesel) at different engine rotation speeds. Concentrations in the range 6 to 45 ppmV for ethylene, 109 to 1,231 ppmV for carbon monoxide, 75 to 868 ppmV for nitrogen oxides and 3 to 354 ppmV for sulfur dioxide were obtained. The results indicate that the detection techniques used were sufficiently selective and sensitive to detect the gaseous species mentioned above in the ppmV range

Improving Metered Dose Inhaler Technique in the Emergency Department: A Prospective Study

Objective: To determine if improvement in patients’ metered dose inhaler (MDI) technique could be achieved in the emergency department (ED) with the use of a simple illustrated instruction sheet. Methods: Prospective evaluation of a convenience sample of patients with asthma or COPD. Patients were first subjectively and objectively evaluated on their usual MDI technique, then were given an illustrated instruction sheet to study for 5 minutes. There was no verbal coaching prior to the post-test. A post-test evaluation was then performed. Results were compared using paired Student t test. Results: A total of 115 patients were enrolled. Mean age was 34.9±13.1 years, and mean years using MDI was 5.7±3.8. Subjective improvement in technique was reported by 110 patients (96%) with a mean pre-test score of 7.4±1.5 and post-test score of 9.2±1.1 (p<0.0001, 10 point scale). Objective improvement was achieved in 113 patients (98%) with a mean pretest score of 3.9±1.3 and post-test score of 5.8±1.0 (p<0.0001, 7 point scale), corresponding to a 30% improvement in technique (95% CI: 22,39). Fortyfour patients (38%) reported never having been shown proper MDI technique by a health care professional, and 112 patients (97%) found the instruction sheet helpful. Conclusions: Rapid objective and subjective improvement of MDI technique from both patients’ and physicians’ perspective is possible in the ED with the use of an illustrated instruction sheet, and requires minimal effort from the treating emergency physician

Whole and Particle-Free Diesel Exhausts Differentially Affect Cardiac Electrophysiology, Blood Pressure, and Autonomic Balance in Heart Failure–Prone Rats

Epidemiological studies strongly link short-term exposures to vehicular traffic and particulate matter (PM) air pollution with adverse cardiovascular (CV) events, especially in those with preexisting CV disease. Diesel engine exhaust is a key contributor to urban ambient PM and gaseous pollutants. To determine the role of gaseous and particulate components in diesel exhaust (DE) cardiotoxicity, we examined the effects of a 4-h inhalation of whole DE (wDE) (target PM concentration: 500 µg/m(3)) or particle-free filtered DE (fDE) on CV physiology and a range of markers of cardiopulmonary injury in hypertensive heart failure–prone rats. Arterial blood pressure (BP), electrocardiography, and heart rate variability (HRV), an index of autonomic balance, were monitored. Both fDE and wDE decreased BP and prolonged PR interval during exposure, with more effects from fDE, which additionally increased HRV triangular index and decreased T-wave amplitude. fDE increased QTc interval immediately after exposure, increased atrioventricular (AV) block Mobitz II arrhythmias shortly thereafter, and increased serum high-density lipoprotein 1 day later. wDE increased BP and decreased HRV root mean square of successive differences immediately postexposure. fDE and wDE decreased heart rate during the 4th hour of postexposure. Thus, DE gases slowed AV conduction and ventricular repolarization, decreased BP, increased HRV, and subsequently provoked arrhythmias, collectively suggesting parasympathetic activation; conversely, brief BP and HRV changes after exposure to particle-containing DE indicated a transient sympathetic excitation. Our findings suggest that whole- and particle-free DE differentially alter CV and autonomic physiology and may potentially increase risk through divergent pathways