Source identifications of airborne fine particles using positive matrix factorization and U.S. Environmental Protection Agency positive matrix factorization

The widely used source apportionment model, positive matrix factorization (PMF2), has been applied to various air pollution data. Recently, U.S. Environmental Protection Agency (EPA) developed EPA positive matrix factorization (PMF), a version of PMF that will be freely distributed by EPA. The objectives of this study were to conduct source apportionment studies for particulate matter less than 2.5 microm in aerodynamic diameter (PM(2.5)) speciation data using PMF2 and EPA PMF (version 1.1) and to compare identified sources between the two models. In the present study, ambient PM(2.5) compositional datasets of 24-hr integrated samples collected at EPA Speciation Trends Network monitoring sites in Chicago, IL, and Portland, OR, were analyzed. Both PMF2 and EPA PMF extracted eight sources for the Chicago data and 10 sources for the Portland data. The model-resolved source profiles were similar between two models for both datasets. However, in several sources, the average contributions did not agree well and the time series contributions were not highly correlated. The differences between PMF2 and EPA PMF solutions were caused by the different least-square algorithm and the different nonnegativity constraints. Most of the average source contributions resolved by both models were within 5-95% uncertainty provided by EPA PMF, indicating that the sources resolved by both models were reproducible.     

Factor analysis of submicron particle size distributions near a major United States-Canada trade bridge

A factor analytic model has been applied to resolve and apportion particles based on submicron particle size distributions downwind of a United States-Canada bridge in Buffalo, NY. The sites chosen for this study were located at gradually increasing distances downwind of the bridge complex. Seven independent factors were resolved, including four factors that were common to all of the five sites considered. The common factors were generally characterized by the existence of two or more number and surface area modes. The seven factors resolved were identified as follows: fresh tail-pipe diesel exhaust, local/street diesel traffic, aged/evolved diesel particles, spark-ignition gasoline emissions, background urban emissions, heavy-duty diesel agglomerates, and secondary/transported material. Submicron (<0.5 microm) and ultrafine (<0.1 microm) particle emissions downwind of the bridge were dominated by commercial diesel truck emissions. Thus, this study obtained size distinction between fresh versus aged vehicle exhaust and spark-ignition versus diesel emissions based on the measured high time-resolution particle number concentrations. Because this study mainly used particles <300 nm in diameter, some sources that would usually exhibit number modes >100 nm were not resolved. Also, the resolved profiles suggested that the major number mode for fresh tailpipe diesel exhaust might exist below the detection limit of the spectrometer used. The average particle number contributions from the resolved factors were highest closest to the bridge.     

Commentary: The federal ‘Prenatally and Postnatally Diagnosed Conditions Awareness Act’

The recently enacted federal law, the ‘Prenatally and Postnatally Diagnosed Conditions Awareness Act’ (United States Public Law 110–374) seeks to improve opportunities for parents and pregnant women to anticipate and understand the likely life course of children born with Down syndrome and other (unspecified) conditions. The law is in part a response to the continued growth of prenatal screening and testing. For example, the American College of Obstetricians and Gynecologists' Practice Bulletin 77 recommends that ‘Screening and invasive diagnostic testing for aneuploidies be available to all women who present for prenatal care before 20 weeks of gestation regardless of maternal age.’ Emerging technologies anticipate an era in which the scope of prenatal screening and testing will be much larger than it is today. Inevitably, more women will find themselves facing the hard question of whether to continue or end a pregnancy in which a fetus has been found to have a significant abnormality. While the new federal law is not likely to have a major impact on obstetric practice, it may be a harbinger of renewed wide-scale public debate concerning the ethics of prenatal screening. Copyright © 2009 John Wiley & Sons, Ltd.     

Prenatal diagnosis of Pfeiffer syndrome type II

Pfeiffer syndrome is an autosomal dominant disorder characterized by coronal craniosynostosis, midface hypoplasia, broad thumbs and great toes. On the basis of clinical findings, three subtypes have been delineated. The clinical variability of Pfeiffer syndrome as well as other causes of craniosynostosis can make a prenatal diagnosis based on sonography alone difficult. We describe a fetus in whom sonographic findings (including 3D ultrasound) suggested a Pfeiffer syndrome type II and in which subsequent molecular analysis verified the diagnosis by identifying a de novo mutation in the FGFR2 gene. To the best of our knowledge, this is the first report of a prenatal molecular diagnosis of Pfeiffer syndrome in a patient without family history. Copyright © 2004 John Wiley & Sons, Ltd.     

Performance assessments for the geological storage of carbon dioxide: Learning from the radioactive waste disposal experience

The geological storage of carbon dioxide is currently being considered as a possible technology for reducing emissions to atmosphere. Although there are several operational sites where carbon dioxide is stored in this way, methods for assessing the long-term performance and safety of geological storage are at an early stage of development. In this paper the similarities and differences between this field and the geological disposal of radioactive wastes are considered. Priorities are suggested for the development of performance assessment methods for carbon dioxide storage based on areas where experience from radioactive waste disposal can be usefully applied. These include, inter alia, dealing with the various types of uncertainty, using systematic methodologies to ensure an auditable and transparent assessment process, developing whole system models and gaining confidence to model the long-term system evolution by considering information from natural systems. An important area of data shortage remains the potential impacts on humans and ecosystems.     

Adequacy of Visually Classified Particle Count Statistics From Regional Stream Habitat Surveys1

Abstract: Streamlined sampling procedures must be used to achieve a sufficient sample size with limited resources in studies undertaken to evaluate habitat status and potential management‐related habitat degradation at a regional scale. At the same time, these sampling procedures must achieve sufficient precision to answer science and policy‐relevant questions with an acceptable and statistically quantifiable level of uncertainty. In this paper, we examine precision and sources of error in streambed substrate characterization using data from the Environmental Monitoring and Assessment Program (EMAP) of the U.S. Environmental Protection Agency, which uses a modified “pebble count” method in which particle sizes are visually estimated rather than measured. While the coarse (2?) size classes used in EMAP have little effect on the precision of estimated geometric mean (D_gm) or median (D₅₀) particle diameter, variable classification bias among observers can contribute as much as 0.3?, or about 15‐20%, to the root‐mean‐square error (RMSE) of D_gm or D₅₀ estimates. D_gm and D₅₀ estimates based on EMAP data are nearly equal when fine sediments (<2 mm) are excluded, but otherwise can differ by up to a factor of 2 or more, with D_gm < D₅₀ for gravel‐bed streams. The RMSE of reach‐scale particle size estimates based on visually classified particle count data from EMAP surveys, including variability associated with reoccupying unmarked sample reaches during revisits, is up to five to seven times higher than that reported for traditional measured pebble counts by multiple observers at a plot scale. Nonetheless, a variance partitioning analysis shows that the ratio of among site to revisit variance for several EMAP substrate metrics exceeds 8 for many potential regions of interest, suggesting that the data have adequate precision to be useful in regional assessments of channel morphology, habitat quality, or ecological condition.     

Low back pain among residential carpenters: ergonomic evaluation using OWAS and 2D compression estimation.

Occupational low back pain (LBP) remains a leading safety and health challenge. This cross-sectional investigation measured the prevalence of LBP in residential carpenters and investigated ergonomic risk factors. Ninety-four carpenters were investigated for LBP presence and associated risk factors. Ten representative job-tasks were evaluated using the Ovako Working Posture Analysis System (OWAS) and ErgoMaster 2D software to measure elements of posture, stress, and risk. Job-tasks were found to differ significantly for total lumbar compression and shear at peak loading (p < .001), ranging from 2 956 to 8 606 N and 802 to 1 974 N respectively. OWAS indicated that slight risk for injury was found in 10 job-tasks while distinct risk was found in 7 of the 10 job-tasks. Seven of the 10 job-tasks exceeded the National Institute for Occupational Safety and Health (NIOSH) action limit of 3 400 N for low back loading. The point prevalence for LBP was 14% while the annual prevalence was 38%.     

How Well Does Brazil's Environmental Law Work in Practice? Environmental Impact Assessment and the Case of the Itapiranga Private Sustainable Logging Plan

/ The Itapiranga Sustainable Logging Plan provides an example of how Brazil's licensing system functions for logging companies in the state of Amazonas. Two questions need to be dealt with: "How sustainable can logging in the Amazon be?" and "What and how effective are existing legal mechanisms to deal with logging projects?" The environmental impact assessment (EIA) and environmental impact statement (EIS, known as the RIMA in Brazil), present relatively detailed accounts of biodiversity and the need to adopt conservation strategies to protect it. However, social and health impacts are only superficially addressed. The economic sustainability of the operation over multiple cycles is not demonstrated. The multidisciplinary teams responsible for the EIA and EIS (RIMA) reports are hired by the project proponent, an arrangement inherently carrying the risk of biasing the result. Logging reduces biodiversity, releases greenhouse gases and inflicts social and health costs. These impacts reduce the ability of Amazonian forests to provide environmental services and to supply food and livelihood security to local populations. The reports inflate positive effects such as employment: the estimated number of jobs was cut by more than half in a revision made after the EIA and EIS (RIMA) had been approved. Not only do the reports need to be more realistic in assessing both positive and negative consequences of proposed projects, but better means are needed to ensure that promised mitigatory measures are enforced in practice. Many of the lessons that can be drawn from the Itapiranga Plan are not unique to logging projects and apply to licensing of development activites generally in Brazil and elsewhere.