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Panteliadis P.,Municipal Health Service GGD Amsterdam | Hafkenscheid T.,National Institute for Public Health and the Environment | Cary B.,Sunset Inc. | Diapouli E.,Japan National Institute of Radiological Sciences | And 16 more authors.
Atmospheric Measurement Techniques | Year: 2015

A comparison exercise on thermal-optical elemental carbon/organic carbon (ECOC) analysers was carried out among 17 European laboratories. Contrary to previous comparison exercises, the 17 participants made use of an identical instrument set-up, after correcting for temperature offsets with the application of a recently developed temperature calibration kit (Sunset Laboratory Inc, OR, US). Temperature offsets reported by participants ranged from -93 to +100 °C per temperature step. Five filter samples and two sucrose solutions were analysed with both the EUSAAR2 and NIOSH870 thermal protocols. z scores were calculated for total carbon (TC); nine outliers and three stragglers were identified. Three outliers and eight stragglers were found for EC. Overall, the participants provided results between the warning levels with the exception of two laboratories that showed poor performance, the causes of which were identified and corrected through the course of the comparison exercise. The TC repeatability and reproducibility (expressed as relative standard deviations) were 11 and 15% for EUSAAR2 and 9.2 and 12% for NIOSH870; the standard deviations for EC were 15 and 20% for EUSAAR2 and 20 and 26% for NIOSH870. TC was in good agreement between the two protocols, TCNIOSH870 =0.98 × TCEUSAAR2 (R2 = 1.00, robust means). Transmittance (TOT) calculated EC for NIOSH870 was found to be 20% lower than for EUSAAR2, ECNIOSH870 = 0.80 × ECEUSAAR2 (R2 = 0.96, robust means). The thermograms and laser signal values were compared and similar peak patterns were observed per sample and protocol for most participants. Notable deviations from the typical patterns indicated either the absence or inaccurate application of the temperature calibration procedure and/or pre-oxidation during the inert phase of the analysis. Low or zero pyrolytic organic carbon (POC), as reported by a few participants, is suggested as an indicator of an instrument-specific pre-oxidation. A sample-specific pre-oxidation effect was observed for filter G, for all participants and both thermal protocols, indicating the presence of oxygen donors on the suspended particulate matter. POC (TOT) levels were lower for NIOSH870 than for EUSAAR2, which is related to the heating profile differences of the two thermal protocols. © Author(s) 2015.


Tiemersma E.W.,KNCV Tuberculosis Foundation | Tiemersma E.W.,University of Amsterdam | van der Werf M.J.,KNCV Tuberculosis Foundation | van der Werf M.J.,University of Amsterdam | And 3 more authors.
PLoS ONE | Year: 2011

Background: The prognosis, specifically the case fatality and duration, of untreated tuberculosis is important as many patients are not correctly diagnosed and therefore receive inadequate or no treatment. Furthermore, duration and case fatality of tuberculosis are key parameters in interpreting epidemiological data. Methodology and Principal Findings: To estimate the duration and case fatality of untreated pulmonary tuberculosis in HIV negative patients we reviewed studies from the pre-chemotherapy era. Untreated smear-positive tuberculosis among HIV negative individuals has a 10-year case fatality variously reported between 53% and 86%, with a weighted mean of 70%. Ten-year case fatality of culture-positive smear-negative tuberculosis was nowhere reported directly but can be indirectly estimated to be approximately 20%. The duration of tuberculosis from onset to cure or death is approximately 3 years and appears to be similar for smear-positive and smear-negative tuberculosis. Conclusions: Current models of untreated tuberculosis that assume a total duration of 2 years until self-cure or death underestimate the duration of disease by about one year, but their case fatality estimates of 70% for smear-positive and 20% for culture-positive smear-negative tuberculosis appear to be satisfactory. © 2011 Tiemersma et al.


Panteliadis P.,Municipal Health Service GGD Amsterdam | Strak M.,Municipal Health Service GGD Amsterdam | Hoek G.,University Utrecht | Weijers E.,Energy Research Center of the Netherlands | And 3 more authors.
Atmospheric Environment | Year: 2014

A regulation was implemented on 9/1/2009, excluding Euro 0, I and II heavy duty vehicles from entering Amsterdam's Low Emission Zone (LEZA). The current study investigated whether and to what extent this regulation had an effect on air quality. Data for a period starting two years before the regulation up to 31 December 2010 were obtained from two monitoring sites within the LEZA, one located in a street frequently used by heavy-duty vehicles, and one at an urban background location. The difference in concentrations of NO2, NOx, PM10 and soot, between the two sites was attributed to traffic. Soot was measured by two proxies, Elemental Carbon (EC) and Absorbance that showed a significant mutual correlation. The traffic contribution concentrations measured were adjusted for wind direction, wind speed, type of day (weekday/weekend) and traffic intensity. Since the implementation of the LEZA, the traffic contribution concentrations compared to the roadside site concentrations were decreased by 4.9% (95%-CI: 3.0-6.9%) for NO2, 5.9% (95%-CI: 3.7-6.4%) for NOx, 5.8% (95%-CI: 3.3-8.4%) for PM10, 7.7% (95%-CI: 2.3-13.0%) for Absorbance and 12.9% (95%-CI: 5.2-20.5%) for EC. The current study demonstrated significant decreases in traffic-related air pollution concentrations in the vicinity of a roadside monitoring station after the implementation of a low emission zone in Amsterdam. © 2014 Elsevier Ltd.

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