Characterization and intercomparison of aerosol absorption photometers: Result of two intercomparison workshops

Absorption photometers for real time application have been available since the 1980s, but the use of filter-based instruments to derive information on aerosol properties (absorption coefficient and black carbon, BC) is still a matter of debate. Several workshops have been conducted to investigate the performance of individual instruments over the intervening years. Two workshops with large sets of aerosol absorption photometers were conducted in 2005 and 2007. The data from these instruments were corrected using existing methods before further analysis. The inter-comparison shows a large variation between the responses to absorbing aerosol particles for different types of instruments. The unit to unit variability between instruments can be up to 30% for Particle Soot Absorption Photometers (PSAPs) and Aethalometers. Multi Angle Absorption Photometers (MAAPs) showed a variability of less than 5%. Reasons for the high variability were identified to be variations in sample flow and spot size. It was observed that different flow rates influence system performance with respect to response to absorption and instrumental noise. Measurements with non absorbing particles showed that the current corrections of a cross sensitivity to particle scattering are not sufficient. Remaining cross sensitivities were found to be a function of the total particle load on the filter. The large variation between the response to absorbing aerosol particles for different types of instruments indicates that current correction functions for absorption photometers are not adequate

Post-Race Plasma Angiotensin Converting Enzyme in Thoroughbred Horses with or without Furosemide

Introduction: Exercise-Induced Pulmonary Haemorrhage (EIPH) results from hypertensive episodes associated with intense exercise and can negatively impact on athletic performance. ACE shedding from the pulmonary endothelium is increased during lung disease. This study investigated an association between EIPH and post-race plasmatic ACE and the effect of furosemide administration on ACE activity. Methods: Blood samples from 73 horses were collected post-race. ACE activity was measured using a fluorimetric method. Respiratory endoscopies determined occurrence and grade of EIPH. Comparison between horses medicated with furosemide pre-race or not medicated and EIPH positive or negative were conducted by independent samples t-tests. Regression analysis was used to investigate the association between ACE activity and EIPH grade for all horses. Other variables analysed included time to endoscopy and haematocrit. Results: Mean ACE activity in horses not medicated with furosemide (n= 47; 91.7 ± 15.9) was significantly higher (p = 0.002) than in horses medicated (n = 26; 79.6 ± 13.9). Horses EIPH positive and medicated with furosemide (n=20; ACE 78.2 ± 11.9) had significantly lower ACE (p = 0.009) than horses EIPH positive not medicated (n = 17; ACE 90.9 ± 15.9). Regression analysis indicated a polynomial relationship between mean ACE activity and EIPH grade (0, 1, 2 or 3+4+5; adjusted r2 = 0.99; p < 0.001). No other comparisons were statistically significant. Conclusion: Results indicated associations between ACE activity, EIPH grade and furosemide administration and investigations in the potential use of ACE as a biomarker for EIPH severity in controlled studies are warranted. Declarations: This research was conducted with Ethics approval from The Animal Ethics Committee at WINTEC, and informed owner consent was obtained for horses include in this study. This research was partially funded by a Research Grant from WINTEC. There are no competing interests identified

Characterization and intercomparison of aerosol absorption photometers: result of two intercomparison workshops

Absorption photometers for real time application have been available since the 1980s, but the use of filterbased instruments to derive information on aerosol properties (absorption coefficient and black carbon, BC) is still a matter of debate. Several workshops have been conducted to investigate the performance of individual instruments over the intervening years. Two workshops with large sets of aerosol absorption photometers were conducted in 2005 and 2007. The data from these instruments were corrected using existing methods before further analysis. The intercomparison shows a large variation between the responses to absorbing aerosol particles for different types of instruments. The unit to unit variability between instruments can be up to 30% for Particle Soot Absorption Photometers (PSAPs) and Aethalometers. Multi Angle Absorption Photometers (MAAPs) showed a variability of less than 5%. Reasons for the high variability were identified to be variations in sample flow and spot size. It was observed that different flow rates influence system performance with respect to response to absorption and instrumental noise. Measurements with non absorbing particles showed that the current corrections of a cross sensitivity to particle scattering are not sufficient. Remaining cross sensitivities were found to be a function of the total particle load on the filter. The large variation between the response to absorbing aerosol particles for different types of instruments indicates that current correction functions for absorption photometers are not adequate.

Characterization and intercomparison of aerosol absorption photometers: Result of two intercomparison workshops

Absorption photometers for real time application have been available since the 1980s, but the use of filter-based instruments to derive information on aerosol properties (absorption coefficient and black carbon, BC) is still a matter of debate. Several workshops have been conducted to investigate the performance of individual instruments over the intervening years. Two workshops with large sets of aerosol absorption photometers were conducted in 2005 and 2007. The data from these instruments were corrected using existing methods before further analysis. The inter-comparison shows a large variation between the responses to absorbing aerosol particles for different types of instruments. The unit to unit variability between instruments can be up to 30% for Particle Soot Absorption Photometers (PSAPs) and Aethalometers. Multi Angle Absorption Photometers (MAAPs) showed a variability of less than 5%. Reasons for the high variability were identified to be variations in sample flow and spot size. It was observed that different flow rates influence system performance with respect to response to absorption and instrumental noise. Measurements with non absorbing particles showed that the current corrections of a cross sensitivity to particle scattering are not sufficient. Remaining cross sensitivities were found to be a function of the total particle load on the filter. The large variation between the response to absorbing aerosol particles for different types of instruments indicates that current correction functions for absorption photometers are not adequate. © Author(s) 2011