Estimating pollutant exposures from coal fired power plants in a rural region

A critical issue in epidemiological studies of ambient air pollution is the measurement of pollutant exposure in the study population. Accurate characterization of air quality is necessary in any study relating exposure to health effects, and is essential in attempting to quantify risk estimates for specific exposure concentrations. Despite the importance of accurate air quality data, most epidemiological investigations have used relatively crude estimates of pollutant exposure. Results from such investigations may be only qualitative at best.Early studies of air pollution health effects were limited by a lack of air pollution monitoring sites, and thus, exposures were often based on surrogate measures such as tons of coal consumed. With the introduction of reliable and reasonably accurate measurements of pollutant concentrations, several important constraints remained. These limitations include the relatively sparse siting of monitor sites and the variable relationship of monitor concentrations to the exposure experience of the study population. Other considerations in using monitor data include the selection of the pollutant specie(s), the duration of the sampling period, the use of short-term versus long-term averages, peak versus mean concentrations and the cyclical variation in pollutant levels.The Chestnut Ridge region of Pennsylvania is the site of an ongoing study of health effects from air pollution. This site was selected in part because of the extensive and well maintained air pollution monitoring network, and the previous studies of pollutant dispersion in the area. Several studies of respiratory symptoms and pulmonary function in women and school age children have been carried out in the area. The current study evaluated aspects of air pollution exposure estimates which are relevant to these epidemiologic studies. Subsequent papers will discuss findings of the various epidemiologic studies which employ these air pollution measures

Nonstationary spatiotemporal Bayesian data fusion for pollutants in the near‐road environment

Concentrations of near‐road air pollutants (NRAPs) have increased to very high levels in many urban centers around the world, particularly in developing countries. The adverse health effects of exposure to NRAPs are greater when the exposure occurs in the near‐road environment as compared to background levels of pollutant concentration. Therefore, there is increasing interest in monitoring pollutant concentrations in the near‐road environment. However, due to various practical limitations, monitoring pollutant concentrations near roadways and traffic sources is generally rather difficult and expensive. As an alternative, various deterministic computer models that provide predictions of pollutant concentrations in the near‐road environment, such as the research line‐source dispersion model (RLINE), have been developed. A common feature of these models is that their outputs typically display systematic biases and need to be calibrated in space and time using observed pollutant data. In this paper, we present a nonstationary Bayesian data fusion model that uses a novel data set on monitored pollutant concentrations (nitrogen oxides or NOx and fine particulate matter or PM2.5) in the near‐road environment and, combining it with the RLINE model output, provides predictions at unsampled locations. The model can also be used to evaluate whether including the RLINE model output leads to improved pollutant concentration predictions and whether the RLINE model output captures the spatial dependence structure of NRAP concentrations in the near‐road environment. A defining characteristic of the proposed model is that we model the nonstationarity in the pollutant concentrations by using a recently developed approach that includes covariates, postulated to be the driving force behind the nonstationary behavior, in the covariance function.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151876/1/env2581.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151876/2/env2581_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151876/3/ENV_2581-Supp-0001-BDF_supp_material.pd

Assessment of subsurface VOCs using a chemical microsensor array. Final report

This report describes the results of laboratory investigations of several performance parameters relevant to surface-acoustic-wave (SAW) chemical sensor arrays for the measurement of volatile organic compounds (VOCs) in contaminated soil and groundwater. The small size, low cost, sensitivity and selectivity of such instruments promise improvements in the quality and quantity of data used to guide site assessment and restoration efforts. In this investigation, calibrations were performed for 15 different coated SAW sensors. Each sensor was exposed to six VOCs selected to represent three chemical classes of contaminants that are commonly found at waste sites (i.e., aliphatic, aromatic and chlorinated hydrocarbons). A new pattern recognition method was developed for determining which coated sensors would maximize the selectivity and accuracy of quantitation for a given set of vapor contaminants. Using this method, an optimal subwet of four coated sensors was selected for testing in a prototype microsensor instrument. Additional laboratory experiments were performed with this optimized array to assess the limits of detection and linear response ranges for the representative vapors, as well as the additivity of responses to vapors in binary mixtures, temperature and humidity effects, aging effects, and other performance parameters related to the application of this technology to soil and groundwater VOC monitoring. Results demonstrate that SAW microsensor arrays can identify and quantify specific VOCs at concentrations in the {mu}g/L to mg/L range when present alone or in simple (e.g., binary) mixtures. SAW sensor technology offers a potentially effective alternative to existing field instrumentation for headspace analysis, soil vapor monitoring, and vacuum extraction process monitoring of VOCs in subsurface media

Man-made noise in our living environments

The ITU’s (International Telecommunication Union’s) man-made noise levels are based on measurements performed in the 1970s. Some measurements have been carried out since then, showing that noise caused by automotive ignition systems has been reduced, but manmade noise in business areas and city centers increased, especially due to the widespread use of electronic systems. The interference scenario also changed, from analog communication systems in relatively free-space conditions, to digital systems in living areas, often semi-enclosed such as offi ces, industrial production plants, and even inside cars and trains. Several measurements have therefore been carried out to estimate the level of man-made noise in these semi-enclosed environments

Ventilation rates in recently constructed U.S. school classrooms

Low ventilation rates (VRs) in schools have been associated with absenteeism, poorer academic performance, and teacher dissatisfaction. We measured VRs in 37 recently constructed or renovated and mechanically ventilated U.S. schools, including LEED and EnergyStarâ certified buildings, using CO2 and the steadyâ state, buildâ up, decay, and transient mass balance methods. The transient mass balance method better matched conditions (specifically, changes in occupancy) and minimized biases seen in the other methods. During the school day, air change rates (ACRs) averaged 2.0±1.3 hourâ 1, and only 22% of classrooms met recommended minimum ventilation rates. HVAC systems were shut off at the school day close, and ACRs dropped to 0.21±0.19 hourâ 1. VRs did not differ by building type, although costâ cutting and comfort measures resulted in low VRs and potentially impaired IAQ. VRs were lower in schools that used unit ventilators or radiant heating, in smaller schools and in larger classrooms. The steadyâ state, buildâ up, and decay methods had significant limitations and biases, showing the need to confirm that these methods are appropriate. Findings highlight the need to increase VRs and to ensure that energy saving and comfort measures do not compromise ventilation and IAQ.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138411/1/ina12384.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138411/2/ina12384_am.pd

Probing impulsive strain propagation with x-ray pulses

Pump-probe time-resolved x-ray diffraction of allowed and nearly forbidden reflections in InSb is used to follow the propagation of a coherent acoustic pulse generated by ultrafast laser-excitation. The surface and bulk components of the strain could be simultaneously measured due to the large x-ray penetration depth. Comparison of the experimental data with dynamical diffraction simulations suggests that the conventional model for impulsively generated strain underestimates the partitioning of energy into coherent modes.Comment: 4 pages, 2 figures, LaTeX, eps. Accepted for publication in Phys. Rev. Lett. http://prl.aps.or

Holographic analysis of diffraction structure factors

We combine the theory of inside-source/inside-detector x-ray fluorescence holography and Kossel lines/x ray standing waves in kinematic approximation to directly obtain the phases of the diffraction structure factors. The influence of Kossel lines and standing waves on holography is also discussed. We obtain partial phase determination from experimental data obtaining the sign of the real part of the structure factor for several reciprocal lattice vectors of a vanadium crystal.Comment: 4 pages, 3 figures, submitte

Particulate matter concentrations in residences: an intervention study evaluating stand‐alone filters and air conditioners

This study, a randomized controlled trial, evaluated the effectiveness of free‐standing air filters and window air conditioners (ACs) in 126 low‐income households of children with asthma. Households were randomized into a control group, a group receiving a free‐standing HEPA filter placed in the child’s sleeping area, and a group receiving the filter and a window‐mounted AC. Indoor air quality (IAQ) was monitored for week‐long periods over three to four seasons. High concentrations of particulate matter (PM) and carbon dioxide were frequently seen. When IAQ was monitored, filters reduced PM levels in the child’s bedroom by an average of 50%. Filter use varied greatly among households and declined over time, for example, during weeks when pollutants were monitored, filter use was initially high, averaging 84 ± 27%, but dropped to 63 ± 33% in subsequent seasons. In months when households were not visited, use averaged only 34 ± 30%. Filter effectiveness did not vary in homes with central or room ACs. The study shows that measurements over multiple seasons are needed to characterize air quality and filter performance. The effectiveness of interventions using free‐standing air filters depends on occupant behavior, and strategies to ensure filter use should be an integral part of interventions. Practical Implications Environmental tobacco smoke (ETS) increased particulate matter (PM) levels by about 14 μg/m 3 and was often detected using ETS‐specific tracers despite restrictions on smoking in the house as reported on questionnaires administered to caregivers. PM concentrations depended on season, filter usage, relative humidity, air exchange ratios, number of children, outdoor PM levels, sweeping/dusting, and presence of a central air conditioner (AC). Free‐standing air filters can be an effective intervention that provides substantial reductions in PM concentrations if the filters are used. However, filter use was variable across the study population and declined over the study duration, and thus strategies are needed to encourage and maintain use of filters. The variability in filter use suggests that exposure misclassification is a potential problem in intervention studies using filters. The installation of a room AC in the bedroom, intended to limit air exchange ratios, along with an air filter, did not lower PM levels more than the filter alone.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91183/1/j.1600-0668.2011.00761.x.pd

Emergence: Key physical issues for deeper philosophical inquiries

A sketch of three senses of emergence and a suggestive view on the emergence of time and the direction of time is presented. After trying to identify which issues philosophers interested in emergent phenomena in physics view as important I make several observations pertaining to the concepts, methodology and mechanisms required to understand emergence and describe a platform for its investigation. I then identify some key physical issues which I feel need be better appreciated by the philosophers in this pursuit. I end with some comments on one of these issues, that of coarse-graining and persistent structures.Comment: 16 pages. Invited Talk at the Heinz von Foerster Centenary International Conference on Self-Organization and Emergence: Emergent Quantum Mechanics (EmerQuM11). Nov. 10-13, 2011, Vienna, Austria. Proceedings to appear in J. Phys. (Conf. Series