Quantifying residual elemental carbon by thermal-optical analysis using an extended IMPROVE_A protocol with higher maximum temperature.

Thermal-optical analysis (TOA) has long been used to quantify organic carbon (OC) and elemental carbon (EC) on quartz-fiber filter samples collected in national ambient air monitoring networks. In the routine analysis of samples from the Chemical Speciation Network (CSN), we observed a considerable fraction of filter punches that remain gray or black in color after TOA was completed, suggesting the presence of EC that was not fully evolved at the highest temperature specified by the IMPROVE_A protocol (840°C). In this work, we explored the operational conditions necessary to evolve and quantify such residual EC. First, four heavily loaded CSN samples were analyzed to evaluate modifications to the IMPROVE_A protocol. We found that adding a higher temperature step at 930°C more effectively evolved the residual EC than did lengthening the duration of the 840°C step. Compared with the standard IMPROVE_A results, the modified protocol evolved additional EC of 1.08 to 4.45 µg cm-2 in mass, or 0.12 to 0.50 µg m-3 in concentration. This excess EC accounts for 27.1% to 45.3% of the total EC and 7.6% to 25.1% of the total carbon by standard IMPROVE_A. We then analyzed over 2600 samples from CSN using the extended IMPROVE_A protocol with higher maximum temperature (930°C). A total of 168 samples (6.4% of the total samples analyzed) contained measurable EC at the 930°C step. The average fraction of the evolvable residual EC mass in total EC is 5.7%, and up to 28% for samples with high total EC mass loading (i.e., 95th percentile and above).Implications: Our results suggest that CSN EC measured by the standard IMPROVE_A protocol should be considered a lower limit, and that a higher maximum heating temperature can be used to better quantify EC from CSN sites impacted by fresh urban emissions.

Granuloma annulare on the palms.

We present the case of a 72-year-old man with a one-week history of a red rash on the palms of both hands. A 4mm punch biopsy revealed interstitial granulomatous inflammation within the dermis and a colloidal iron stain showed increased dermal acid mucin. Immunohistochemical staining for CD68 confirmed the presence of abundant histiocytes within the dermis. The clinical and pathological correlation was consistent with the diagnosis of interstitial granuloma annulare. Exclusive involvement of the palms is a rare presentation and serves as a reminder for practitioners to keep granuloma annulare in their differential diagnosis when observing palmar plaques.

Decreasing Vanadium Footprint of Bunker Fuel Emissions.

The Interagency Monitoring of Protected Visual Environments (IMPROVE) network measures the chemical composition of atmospheric particulate matter at over 160 locations throughout the United States. As part of the routine quality control process, we noted decreases in the network-wide vanadium (V) and nickel (Ni) concentrations in 2015 relative to the previous years. Enriched V and Ni with respect to soil are indicative of heavy fuel oil burning and are often used as tracers for emissions from marine vessels. Multiple regulations on the fuel used by marine vessels were implemented in North America since 2010, and the most sweeping regulation was implemented at the start of 2015. The 2015 regulations reduced the allowable fuel oil sulfur concentrations within the North America Emissions Control Area from 1.0% to 0.1% to reduce the environmental and human health impacts of sulfates. As a side effect, these requirements economically favored fuels with lower V and Ni concentrations. The atmospheric concentrations of V and Ni decreased markedly at many IMPROVE monitoring sites, particularly sites near major ports. Between 2011 and 2015, annual mean V concentrations measured on IMPROVE samples collected near the ports of Seattle, Washington and New Orleans, Louisiana decreased by 35% and 85%, respectively. These decreases have brought the coastal V and Ni concentrations much closer to those measured far inland.

Assessing the Suitability of Historical PM(2.5) Element Measurements for Trend Analysis.

The IMPROVE (Interagency Monitoring of Protected Visual Environments) network has characterized fine particulate matter composition at locations throughout the United States since 1988. A main objective of the network is to evaluate long-term trends in aerosol concentrations. Measurements inevitably advance over time, but changes in measurement technique have the potential to confound the interpretation of long-term trends. Problems of interpretation typically arise from changing biases, and changes in bias can be difficult to identify without comparison data that are consistent throughout the measurement series, which rarely exist. We created a consistent measurement series for exactly this purpose by reanalyzing the 15-year archives (1995-2009) of aerosol samples from three sites - Great Smoky Mountains National Park, Mount Rainier National Park, and Point Reyes National Seashore-as single batches using consistent analytical methods. In most cases, trend estimates based on the original and reanalysis measurements are statistically different for elements that were not measured above the detection limit consistently over the years (e.g., Na, Cl, Si, Ti, V, Mn). The original trends are more reliable for elements consistently measured above the detection limit. All but one of the 23 site-element series with detection rates >80% had statistically indistinguishable original and reanalysis trends (overlapping 95% confidence intervals).

Reanalysis of archived IMPROVE PM2.5 samples previously analyzed over a 15-year period.

The IMPROVE (Interagency Monitoring of Protected Visual Environments) network has collected airborne particulate matter (PM) samples at locations throughout the United States since 1988. These samples have been analyzed for elemental content using analytical methods that evolved over the years. Changes in analytical methods sometimes introduced shifts in reported concentrations that are evident in the historical record. We sought to illuminate the effects of methodological changes by reanalyzing archived samples with current methods. To test the feasibility of this approach, the 15-year archive of PM samples from Great Smoky Mountains National Park was selected for reanalysis as a single analytical batch using a common protocol and calibration. Comparisons of the reanalyses and original analyses indicate that concentrations of all but one measured element, Br, remained stable on the filters over years of storage. The agreement between the two analyses varied with element and original measurement method. For elements measured well above their contemporary detection limits - S, K, Ca, Fe, and Zn - the reanalysis established that method changes had limited impacts on reported concentrations, generally <10%. For elements originally measured near their detection limits, reanalysis confirmed the presence of discontinuities in the data record, many of which were previously recognized and documented as method-related.

Identifying sources of uncertainty from the inter-species covariance of measurement errors.

A standard metric of measurement precision in environmental monitoring is the variance of differences between duplicate (collocated) samples. With duplicate measurements of multiple species, we can extend this variance analysis to include the interspecies covariance of differences between duplicate samples; these covariances can provide clues about the sources of error. We illustrate the potential of such an analysis with atmospheric aerosol measurements from two national air quality monitoring networks: Interagency Monitoring of Protected Visual Environments (IMPROVE) and Speciation Trends Network (STN). These aerosol "speciation" networks provide the multivariate data sets needed to characterize error covariance by operating duplicate samplers at several of their monitoring locations and analyzing both the collected aerosol samples for multiple species. We observe covariance among the measurement differences for multiple species in both networks. The covariance among measurement differences for soil-derived elements suggests an error associated with the particle size discrimination step in sampling, which is not currently included in either network's uncertainty estimates. The multivariate statistical analyses of aerosol speciation data performed by standard source apportionment models assume that measurement errors in different species are independent of each other; the present analysis invalidates this assumption for several species measured by IMPROVE and STN.

Estimating precision using duplicate measurements.

Precision is a concept for which there is no universally accepted metric. Reports of precision vary depending on the formula and inclusion criteria used to calculate them. To properly interpret and utilize reported precisions, the user must understand exactly what the precision represents. This paper uses duplicate Interagency Monitoring of Protected Visual Environments (IMPROVE) measurements to illustrate distinctions among different approaches to reporting precision. Three different metrics are used to estimate the precision from the relative differences between the duplicate measurements: the root mean square (RMS), the mean absolute value, and a percentile spread. Precisions calculated using the RMS relative difference yield wide distributions that tend to overestimate most of the observed differences. Precisions calculated using percentiles of the relative differences yield narrower distributions that tend to fit the bulk of the observed differences very well. Precisions calculated using the mean absolute relative difference lie between the other two precision estimates. All three approaches underestimate the observed differences for a small percentage of outliers.

Toward establishing the stability of multi-year monitoring of elements in airborne particles.

Crocker Nuclear Laboratory uses a custom built energy-dispersive X-ray fluorescence system with a molybdenum anode to provide routine analysis of elements from nickel to zirconium and lead in Interagency Monitoring of Protected Visual Environments (IMPROVE) samples. Standard methods are used to ensure accuracy and statistical control of the data, including repeated analysis of single-element standards, standard reference materials, and selected actual samples from the IMPROVE network. This paper compares the short-term (week) precision and long-term (2-yr) reproducibility revealed by the actual sample reanalyses. Currently reported analytical uncertainties are shown to predict actual 2-yr reproducibility within a factor of 2.

Considerations in the use of ozone and PM(2.5) data for exposure assessment.

The US national ambient-air monitoring network, created to verify compliance with health-based standards, now doubles as an important source of exposure data for the epidemiological analyses on which these standards increasingly rest, particularly in the case of ozone and PM(2.5). This paper was written for a workshop called to facilitate and inform the use of routine ozone and PM(2.5) data by the Environmental Public Health Tracking Network. It examines the fit between priorities that shape regulatory monitoring and modeling and the data needs of public health tracking.

An empirical approach to estimating detection limits using collocated data.

Measurements of trace species generally become less certain as concentrations decrease. Data analysts need guidance on the ranges in which particular measurements are meaningful. This guidance is normally stated in the form of detection limits. The International Union for Pure and Applied Chemistry (IUPAC) has defined several parameters to characterize measurement detection limits (Currie, L. A. Pure Appl. Chem. 1995, 67, 1699). The published guidelines envision an ability to prepare reference materials with concentrations close to the detection limits using the same methods as for normal samples. For multianalyte methods such as X-ray fluorescence (XRF), multiple reference materials may be required for each analyte to characterize the effects of interferences. The creation and characterization of such complex reference materials atthe detection limits of modern XRF systems represents a considerable technical challenge. This paper describes an observational approach to estimating the detection limits defined by IUPAC. Our empirical approach takes advantage of collocated (duplicate) measurements that are routinely collected by the Interagency Monitoring of Protected Visual Environments (IMPROVE) network and Speciation Trends Network (STN). The analysis is successfully demonstrated by deriving detection limits at the measurement system level for six elements measured on PM2.5 samples by XRF in both networks. The two networks' detection limits are found to be similar in terms of loading (areal density, ng cm(-2)) on the filters as measured by the XRF instruments despite many differences in sample collection, handling, and analysis. IMPROVE detection limits are an order of magnitude lowerthan STN's in terms of atmospheric concentrations (ng m(-3)), because IMPROVE uses smaller fitters and higher flow rates which lead to more concentrated sample deposits.

Overview of the reanalysis of the Harvard Six Cities Study and American Cancer Society Study of Particulate Air Pollution and Mortality.

This article provides an overview of the Reanalysis Study of the Harvard Six Cities and the American Cancer Society (ACS) studies of particulate air pollution and mortality. The previous findings of the studies have been subject to debate. In response, a reanalysis team, comprised of Canadian and American researchers, was invited to participate in an independent reanalysis project to address the concerns. Phase I of the reanalysis involved the design of data audits to determine whether each study conformed to the consistency and accuracy of their data. Phase II of the reanalysis involved conducting a series of comprehensive analyses using alternative statistical methods. Alternative models were also used to identify covariates that may confound or modify the association of particulate air pollution as well as identify sensitive population subgroups. The audit demonstrated that the data in the original analyses were of high quality, as were the risk estimates reported by the original investigators. The sensitivity analysis illustrated that the mortality risk estimates reported in both studies were found to be robust against alternative Cox models. Detailed investigation of the covariate effects found a significant modifying effect of education and a relative risk of mortality associated with fine particles and declining education levels. The study team applied spatial analytic methods to the ACS data, resulting in various levels of spatial autocorrelations supporting the reported association for fine particles mortality of the original investigators as well as demonstrating a significant association between sulfur dioxide and mortality. Collectively, our reanalysis suggest that mortality may be attributable to more than one component of the complex mixture of ambient air pollutants for U.S. urban areas.

Retrospective data quality audits of the Harvard Six Cities and American Cancer Society studies.

The Harvard Six Cities (6-Cities) and American Cancer Society (ACS) studies are longitudinal cohort mortality studies of large populations that provided important information about the human health effects associated with long-term exposure to fine particulate air pollution. Possible changes to federal regulation of particulates prompted a review of data collection methods, analysis, and reported results from these two studies. This article describes the methodology used to conduct quality assurance audits of both studies and summarizes the audit findings. Statistically based, randomly selected samples of 250 health questionnaires and 250 death certificates from each study were audited against data from analysis files. In cases where study-specific data could not be located, validation was performed using information and data from other sources. Some errors were found in programming and data transformation in both studies, but none affected the results of the original investigations. Both audits confirmed that the published studies are an accurate representation of the collected data. The audits also underscored the importance of adequate attention to documentation and record-keeping practices during the conduct of all studies and proper archiving at their conclusion.

Day-of-Week behavior of atmospheric ozone in three U.S. cities.

The weekly cycles of atmospheric ozone (O3) are of interest because they provide information about the response of O3 to changes in anthropogenic emissions from weekdays to weekends. The weekly behavior of O3 in Chicago, IL; Philadelphia, PA; and Atlanta, GA, is contrasted. In Chicago and Philadelphia, maximum 1-hr average O3 increases on weekends. In Atlanta, O3 builds up from Mondays to Fridays and declines during weekends. In all three areas, volatile organic compound (VOC)/nitrogen oxides (NOx) ratios are higher during weekends, resulting from greater than proportionate decreases in NOx relative to VOC emissions. The VOC/NOx ratios correlate with maximum 1-hr O3 concentrations in Chicago, a response consistent with a VOC-sensitive airshed. A weak correlation between O3 concentrations and VOC/NOx ratios in Philadelphia suggests the impact of transported O3, which is formed in upwind VOC-sensitive locations that may be hundreds of kilometers away. Ozone concentrations in Atlanta do not correlate with VOC/NOx ratios but with concentrations of NOx and total reactive nitrogen (NOy) carried over from the previous day. When data from 1986-1990 and 1995-1999 are compared, only small differences in the weekly behavior of O3 are observed in Chicago and Philadelphia. The day-of-week differences in O3 are amplified in the more recent period in Atlanta, a possible result of urban growth.

Metastatic endocervical adenocarcinoma presenting as a virilizing ovarian mass during pregnancy.

BACKGROUND: We report a case of metastatic endocervical adenocarcinoma that presented as a virilizing ovarian mass in a young pregnant woman and simulated a primary ovarian endometrioid tumor. CASE: A 34-year-old woman underwent cesarean delivery and right salpingo-oophorectomy at 34 weeks' gestation for a 32-cm androgen-producing ovarian mass. The ovarian tumor, initially interpreted as a primary ovarian endometrioid carcinoma, was demonstrated to represent metastatic endocervical endometrioid adenocarcinoma based on detection of human papillomavirus 16 (HPV-16) deoxyribonucleic acid in the tumor by in situ hybridization. The hysterectomy specimen demonstrated an endocervical adenocarcinoma associated with adenocarcinoma in situ that also contained HPV-16. CONCLUSION: Human papillomavirus is considered an etiological agent in the development of endocervical adenocarcinomas, having been demonstrated in greater than 90% of tumors. In contrast, recent studies have concluded that HPV is unlikely to play an etiological role in ovarian neoplasia. The demonstration of HPV-16 in both the endocervical and ovarian carcinomas in this patient supports the interpretation that the ovarian tumor is a metastasis.