Wildfires Increase Concentrations of Hazardous Air Pollutants in Downwind Communities

Due in part to climate change, wildfire activity is increasing, with the potential for greater public health impact from smoke in downwind communities. Studies examining the health effects of wildfire smoke have focused primarily on fine particulate matter (PM2.5), but there is a need to better characterize other constituents, such as hazardous air pollutants (HAPs). HAPs are chemicals known or suspected to cause cancer or other serious health effects that are regulated by the United States (US) Environmental Protection Agency. Here, we analyzed concentrations of 21 HAPs in wildfire smoke from 2006 to 2020 at 309 monitors across the western US. Additionally, we examined HAP concentrations measured in a major population center (San Jose, CA) affected by multiple fires from 2017 to 2020. We found that concentrations of select HAPs, namely acetaldehyde, acrolein, chloroform, formaldehyde, manganese, and tetrachloroethylene, were all significantly elevated on smoke-impacted versus nonsmoke days (P < 0.05). The largest median increase on smoke-impacted days was observed for formaldehyde, 1.3 μg/m3 (43%) higher than that on nonsmoke days. Acetaldehyde increased 0.73 μg/m3 (36%), and acrolein increased 0.14 μg/m3 (34%). By better characterizing these chemicals in wildfire smoke, we anticipate that this research will aid efforts to reduce exposures in downwind communities.

An Analysis of CMAQ Gas Phase Dry Deposition over North America Through Grid-Scale and Land-Use Specific Diagnostics in the Context of AQMEII4

The fourth phase of the Air Quality Model Evaluation International Initiative (AQMEII4) is conducting a diagnostic intercomparison and evaluation of deposition simulated by regional-scale air quality models over North America and Europe. In this study, we analyze annual AQMEII4 simulations performed with the Community Multiscale Air Quality Model (CMAQ) version 5.3.1 over North America. These simulations were configured with both the M3Dry and Surface Tiled Aerosol and Gas Exchange (STAGE) dry deposition schemes available in CMAQ. A comparison of observed and modeled concentrations and wet deposition fluxes shows that the AQMEII4 CMAQ simulations perform similarly to other contemporary regional-scale modeling studies. During summer, M3Dry has higher ozone (O3) deposition velocities (Vd) and lower mixing ratios than STAGE for much of the eastern U.S. while the reverse is the case over eastern Canada and along the West Coast. In contrast, during winter STAGE has higher O3 Vd and lower mixing ratios than M3Dry over most of the southern half of the modeling domain while the reverse is the case for much of the northern U.S. and southern Canada. Analysis of the diagnostic variables defined for the AQMEII4 project, i.e. grid-scale and land-use (LU) specific effective conductances and deposition fluxes for the major dry deposition pathways, reveals generally higher summertime stomatal and wintertime cuticular grid-scale effective conductances for M3Dry and generally higher soil grid-scale effective conductances (for both vegetated and bare soil) for STAGE in both summer and winter. On a domain-wide basis, the stomatal grid-scale effective conductances account for about half of the total O3 Vd during daytime hours in summer for both schemes. Employing LU-specific diagnostics, results show that daytime Vd varies by a factor of 2 between LU categories. Furthermore, M3Dry vs. STAGE differences are most pronounced for the stomatal and vegetated soil pathway for the forest LU categories, with M3Dry estimating larger effective conductances for the stomatal pathway and STAGE estimating larger effective conductances for the vegetated soil pathway for these LU categories. Annual domain total O3 deposition fluxes differ only slightly between M3Dry (74.4 Tg/year) and STAGE (76.2 Tg/yr), but pathway-specific fluxes to individual LU types can vary more substantially on both annual and seasonal scales which would affect estimates of O3 damages to sensitive vegetation. A comparison of two simulations differing only in their LU classification scheme shows that the differences in LU cause seasonal mean O3 mixing ratio differences on the order of 1 ppb across large portions of the domain, with the differences generally largest during summer and in areas characterized by the largest differences in the fractional coverages of the forest, planted/cultivated, and grassland LU categories. These differences are generally smaller than the M3Dry vs. STAGE differences outside the summer season but have a similar magnitude during summer. Results indicate that the deposition impacts of LU differences are caused both by differences in the fractional coverages and spatial distributions of different LU categories as well as the characterization of these categories through variables like surface roughness and vegetation fraction in look-up tables used in the land-surface model and deposition schemes. Overall, the analyses and results presented in this study illustrate how the diagnostic grid-scale and LU-specific dry deposition variables adopted for AQMEII4 can provide insights into similarities and differences between the CMAQ M3Dry and STAGE dry deposition schemes that affect simulated pollutant budgets and ecosystem impacts from atmospheric pollution.

Wildfires in the western United States are mobilizing PM2.5-associated nutrients and may be contributing to downwind cyanobacteria blooms

Wildfire activity is increasing in the continental U.S. and can be linked to climate change effects, including rising temperatures and more frequent drought conditions. Wildfire emissions and large fire frequency have increased in the western U.S., impacting human health and ecosystems. We linked 15 years (2006-2020) of particulate matter (PM2.5) chemical speciation data with smoke plume analysis to identify PM2.5-associated nutrients elevated in air samples on smoke-impacted days. Most macro- and micro-nutrients analyzed (phosphorus, calcium, potassium, sodium, silicon, aluminum, iron, manganese, and magnesium) were significantly elevated on smoke days across all years analyzed. The largest percent increase was observed for phosphorus. With the exception of ammonium, all other nutrients (nitrate, copper, and zinc), although not statistically significant, had higher median values across all years on smoke vs. non-smoke days. Not surprisingly, there was high variation between smoke impacted days, with some nutrients episodically elevated >10 000% during select fire events. Beyond nutrients, we also explored instances where algal blooms occurred in multiple lakes downwind from high-nutrient fires. In these cases, remotely sensed cyanobacteria indices in downwind lakes increased two to seven days following the occurrence of wildfire smoke above the lake. This suggests that elevated nutrients in wildfire smoke may contribute to downwind algal blooms. Since cyanobacteria blooms can be associated with the production of cyanotoxins and wildfire activity is increasing due to climate change, this finding has implications for drinking water reservoirs in the western United States, and for lake ecology, particularly alpine lakes with otherwise limited nutrient inputs.

2002-2017 anthropogenic emissions data for air quality modeling over the United States

The United States Environmental Protection Agency (US EPA) has developed a set of annual North American emissions data for multiple air pollutants across 18 broad source categories for 2002 through 2017. The sixteen new annual emissions inventories were developed using consistent input data and methods across all years. When a consistent method or tool was not available for a source category, emissions were estimated by scaling data from the EPA's 2017 National Emissions Inventory with scaling factors based on activity data and/or emissions control information. The emissions datasets are designed to support regional air quality modeling for a wide variety of human health and ecological applications. The data were developed to support simulations of the EPA's Community Multiscale Air Quality model but can also be used by other regional scale air quality models. The emissions data are one component of EPA's Air Quality Time Series Project which also includes air quality modeling inputs (meteorology, initial conditions, boundary conditions) and outputs (e.g., ozone, PM_2.5 and constituent species, wet and dry deposition) for the Conterminous US at a 12 km horizontal grid spacing.

Beyond Particulate Matter Mass: Heightened Levels of Lead and Other Pollutants Associated with Destructive Fire Events in California

As the climate warms, wildfire activity is increasing, posing a risk to human health. Studies have reported on particulate matter (PM) in wildfire smoke, yet the chemicals associated with PM have received considerably less attention. Here, we analyzed 13 years (2006-2018) of PM_2.5 chemical composition data from monitors in California on smoke-impacted days. Select chemicals (e.g., aluminum and sulfate) were statistically elevated on smoke-impacted days in over half of the years studied. Other chemicals, mostly trace metals harmful to human health (e.g., copper and lead), were elevated during particular fires only. For instance, in 2018, lead was more than 40 times higher on smoke days on average at the Point Reyes monitoring station, due mostly to the Camp Fire, burning approximately 200 km away. There was an association between these metals and the combustion of anthropogenic material (e.g., the burning of houses and vehicles). Although still currently rare, these infrastructure fires are likely becoming more common and can mobilize trace metals in smoke far downwind, at levels generally unseen except in the most polluted areas of the country. We hope a better understanding of the chemicals in wildfire smoke will assist in the communication and reduction of public health risks.

The Community Multiscale Air Quality (CMAQ) model versions 5.3 and 5.3.1: system updates and evaluation

The Community Multiscale Air Quality (CMAQ) model version 5.3 (CMAQ53), released to the public in August 2019 and followed by version 5.3.1 (CMAQ531) in December 2019, contains numerous science updates, enhanced functionality, and improved computation efficiency relative to the previous version of the model, 5.2.1 (CMAQ521). Major science advances in the new model include a new aerosol module (AERO7) with significant updates to secondary organic aerosol (SOA) chemistry, updated chlorine chemistry, updated detailed bromine and iodine chemistry, updated simple halogen chemistry, the addition of dimethyl sulfide (DMS) chemistry in the CB6r3 chemical mechanism, updated M3Dry bidirectional deposition model, and the new Surface Tiled Aerosol and Gaseous Exchange (STAGE) bidirectional deposition model. In addition, support for the Weather Research and Forecasting (WRF) model's hybrid vertical coordinate (HVC) was added to CMAQ53 and the Meteorology-Chemistry Interface Processor (MCIP) version 5.0 (MCIP50). Enhanced functionality in CMAQ53 includes the new Detailed Emissions Scaling, Isolation and Diagnostic (DESID) system for scaling incoming emissions to CMAQ and reading multiple gridded input emission files. Evaluation of CMAQ531 was performed by comparing monthly and seasonal mean daily 8 h average (MDA8) O₃ and daily PM_2.5 values from several CMAQ531 simulations to a similarly configured CMAQ521 simulation encompassing 2016. For MDA8 O₃, CMAQ531 has higher O₃ in the winter versus CMAQ521, due primarily to reduced dry deposition to snow, which strongly reduces wintertime O₃ bias (2-4 ppbv monthly average). MDA8 O₃ is lower with CMAQ531 throughout the rest of the year, particularly in spring, due in part to reduced O₃ from the lateral boundary conditions (BCs), which generally increases MDA8 O₃ bias in spring and fall ( 0.5 μg m^-3). For daily 24 h average PM_2.5, CMAQ531 has lower concentrations on average in spring and fall, higher concentrations in summer, and similar concentrations in winter to CMAQ521, which slightly increases bias in spring and fall and reduces bias in summer. Comparisons were also performed to isolate updates to several specific aspects of the modeling system, namely the lateral BCs, meteorology model version, and the deposition model used. Transitioning from a hemispheric CMAQ (HCMAQ) version 5.2.1 simulation to a HCMAQ version 5.3 simulation to provide lateral BCs contributes to higher O₃ mixing ratios in the regional CMAQ simulation in higher latitudes during winter (due to the decreased O₃ dry deposition to snow in CMAQ53) and lower O₃ mixing ratios in middle and lower latitudes year-round (due to reduced O₃ over the ocean with CMAQ53). Transitioning from WRF version 3.8 to WRF version 4.1.1 with the HVC resulted in consistently higher (1.0-1.5 ppbv) MDA8 O₃ mixing ratios and higher PM_2.5 concentrations (0.1-0.25 μg m^-3) throughout the year. Finally, comparisons of the M3Dry and STAGE deposition models showed that MDA8 O₃ is generally higher with M3Dry outside of summer, while PM_2.5 is consistently higher with STAGE due to differences in the assumptions of particle deposition velocities to non-vegetated surfaces and land use with short vegetation (e.g., grasslands) between the two models. For ambient NH₃, STAGE has slightly higher concentrations and smaller bias in the winter, spring, and fall, while M3Dry has higher concentrations and smaller bias but larger error and lower correlation in the summer.

Variability in Observation-based Onroad Emission Constraints from a Near-road Environment

This study uses Las Vegas near-road measurements of carbon monoxide (CO) and nitrogen oxides (NOx) to test the consistency of onroad emission constraint methodologies. We derive commonly used CO to NOx ratios (ΔCO:ΔNOx) from cross-road gradients and from linear regression using ordinary least squares (OLS) regression and orthogonal regression. The CO to NOx ratios are used to infer NOx emission adjustments for a priori emissions estimates from EPA's MOtor Vehicle Emissions Simulator (MOVES) model assuming unbiased CO. The assumption of unbiased CO emissions may not be appropriate in many circumstances but was implemented in this analysis to illustrate the range of NOx scaling factors that can be inferred based on choice of methods and monitor distance alone. For the nearest road estimates (25m), the cross-road gradient and ordinary least squares (OLS) agree with each other and are not statistically different from the MOVES-based emission estimate while ΔCO:ΔNOx from orthogonal regression is significantly higher than the emitted ratio from MOVES. Using further downwind measurements (i.e., 115m and 300m) increases OLS and orthogonal regression estimates of ΔCO:ΔNOx but not cross-road gradient ΔCO:ΔNOx. The inferred NOx emissions depend on the observation-based method, as well as the distance of the measurements from the roadway and can suggest either that MOVES NOx emissions are unbiased or that they should be adjusted downward by between 10% and 47%. The sensitivity of observation-based ΔCO:ΔNOx estimates to the selected monitor location and to the calculation method characterize the inherent uncertainty of these methods that cannot be derived from traditional standard-error based uncertainty metrics.

Simulating lightning NO production in CMAQv5.2: evolution of scientific updates

This work describes the lightning nitric oxide (LNO) production schemes in the Community Multiscale Air Quality (CMAQ) model. We first document the existing LNO production scheme and vertical distribution algorithm. We then describe updates that were made to the scheme originally based on monthly National Lightning Detection Network (mNLDN) observations. The updated scheme uses hourly NLDN (hNLDN) observations. These NLDN-based schemes are good for retrospective model applications when historical lightning data are available. For applications when observed data are not available (i.e., air quality forecasts and climate studies that assume similar climate conditions), we have developed a scheme that is based on linear and log-linear parameters derived from regression of multiyear historical NLDN (pNLDN) observations and meteorological model simulations. Preliminary assessment for total column LNO production reveals that the mNLDN scheme overestimates LNO by over 40% during summer months compared with the updated hNLDN scheme that reflects the observed lightning activity more faithfully in time and space. The pNLDN performance varies with year, but it generally produced LNO columns that are comparable to hNLDN and mNLDN, and in most cases it outperformed mNLDN. Thus, when no observed lightning data are available, pNLDN can provide reasonable estimates of LNO emissions over time and space for this important natural NO source that influences air quality regulations.

A Measurement-Model Fusion Approach for Improved Wet Deposition Maps and Trends

Air quality models provide spatial fields of wet deposition (WD) and dry deposition that explicitly account for the transport and transformation of emissions from thousands of sources. However, many sources of uncertainty in the air quality model including errors in emissions and meteorological inputs (particularly precipitation) and incomplete descriptions of the chemical and physical processes governing deposition can lead to bias and error in the simulation of WD. We present an approach to bias correct Community Multiscale Air Quality model output over the contiguous United States using observation-based gridded precipitation data generated by the Parameter-elevation Regressions on Independent Slopes Model and WD observations at the National Atmospheric Deposition Program National Trends Network sites. A cross-validation analysis shows that the adjusted annual accumulated WD for NO3 -, NH4 +, and SO4 2- from 2002 to 2012 has less bias and higher correlation with observed values than the base model output without adjustment. Temporal trends in observed WD are captured well by the adjusted model simulations across the entire contiguous United States. Consistent with previous trend analyses, WD NO3 - and SO4 2- are shown to decrease during this period in the eastern half of the United States, particularly in the Northeast, while remaining nearly constant in the West. Trends in WD of NH4 + are more spatially and temporally heterogeneous, with some positive trends in the Great Plains and Central Valley of CA and slightly negative trends in the south.

Characterizing grassland fire activity in the Flint Hills region and air quality using satellite and routine surface monitor data

Prescribed grassland fires in the Flint Hills region of central Kansas and northern Oklahoma are a common tool for land management. Local to regional scale impacts on air quality from grassland fires in this region are not well understood, which is important as these types of prescribed fires may increase in the future to preserve broader areas of native grasses in the central U.S. Routine air quality and deposition measurements from sites in and near the Flint Hills were examined for coincident increases during periods of increased prescribed grassland fires. Prescribed fire activity in this region was quantified using satellite detections and multiple publicly available data products of area burned information. March and April comprise over half (41 to 93%) of all annual fire detections in the Flint Hills region seen from satellites between 2007 and 2018 excluding drought years. Annual total fire detections in this region range between 1 and 12 thousand and account for approximately 3% of all fire detections in the contiguous U.S. Annual acres burned ranged from 0.2 to 2 million acres based on U.S. EPA's National Emission Inventory, which accounts for 4 to 38% of grasslands in the area. A comparison of weekly standardized anomalies suggests a relationship between periods of increased grassland fire activity and elevated levels of PM_2.5 organic carbon, elemental carbon, and potassium. Daily 1-hr maximum ozone (O₃), ammonia (NH₃), sulfur dioxide (SO₂), and oxidized nitrogen gases measured at Konza Prairie also had increased levels when prescribed grassland fire activity was highest. This detailed characterization of prescribed fire activity in the Flint Hills and associated air quality impacts will benefit future efforts to understand changes in atmospheric composition due to changing land management practices.

Simulating lightning NO production in CMAQv5.2: performance evaluations

This study assesses the impact of the lightning nitric oxide (LNO) production schemes in the Community Multiscale Air Quality (CMAQ) model on ground-level air quality as well as aloft atmospheric chemistry through detailed evaluation of model predictions of nitrogen oxides (NO x ) and ozone (O3) with corresponding observations for the US. For ground-level evaluations, hourly O3 and NO x values from the U.S. EPA Air Quality System (AQS) monitoring network are used to assess the impact of different LNO schemes on model prediction of these species in time and space. Vertical evaluations are performed using ozonesonde and P-3B aircraft measurements during the Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) campaign conducted in the Baltimore- Washington region during July 2011. The impact on wet deposition of nitrate is assessed using measurements from the National Atmospheric Deposition Program's National Trends Network (NADP NTN). Compared with the Base model (without LNO), the impact of LNO on surface O3 varies from region to region depending on the Base model conditions. Overall statistics suggest that for regions where surface O3 mixing ratios are already overestimated, the incorporation of additional NO from lightning generally increased model overestimation of mean daily maximum 8 h (DM8HR) O3 by 1-2 ppb. In regions where surface O3 is underestimated by the Base model, LNO can significantly reduce the underestimation and bring model predictions close to observations. Analysis of vertical profiles reveals that LNO can significantly improve the vertical structure of modeled O3 distributions by reducing underestimation aloft and to a lesser degree decreasing overestimation near the surface. Since the Base model underestimates the wet deposition of nitrate in most regions across the modeling domain with the exception of the Pacific Coast, the inclusion of LNO leads to reduction in biases and errors and an increase in correlation coefficients at almost all the NADP NTN sites. Among the three LNO schemes described in Kang et al. (2019), the hNLDN scheme, which is implemented using hourly observed lightning flash data from National Lightning Detection Network (NLDN), performs best for comparisons with ground-level values, vertical profiles, and wet deposition of nitrate; the mNLDN scheme (the monthly NLDN-based scheme) performed slightly better. However, when observed lightning flash data are not available, the linear regression-based parameterization scheme, pNLDN, provides an improved estimate for nitrate wet deposition compared to the base simulation that does not include LNO.

Characterizing CO and NO y Sources and Relative Ambient Ratios in the Baltimore Area Using Ambient Measurements and Source Attribution Modeling

Modeled source attribution information from the Community Multiscale Air Quality model was coupled with ambient data from the 2011 Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality Baltimore field study. We assess source contributions and evaluate the utility of using aircraft measured CO and NO _y relationships to constrain emission inventories. We derive ambient and modeled ΔCO:ΔNO _y ratios that have previously been interpreted to represent CO:NO _y ratios in emissions from local sources. Modeled and measured ΔCO:ΔNO _y are similar; however, measured ΔCO:ΔNO _y has much more daily variability than modeled values. Sector-based tagging shows that regional transport, on-road gasoline vehicles, and nonroad equipment are the major contributors to modeled CO mixing ratios in the Baltimore area. In addition to those sources, on-road diesel vehicles, soil emissions, and power plants also contribute substantially to modeled NO _y in the area. The sector mix is important because emitted CO:NO _x ratios vary by several orders of magnitude among the emission sources. The model-predicted gasoline/diesel split remains constant across all measurement locations in this study. Comparison of ΔCO:ΔNO _y to emitted CO:NO _y is challenged by ambient and modeled evidence that free tropospheric entrainment, and atmospheric processing elevates ambient ΔCO:ΔNO _y above emitted ratios. Specifically, modeled ΔCO:ΔNO _y from tagged mobile source emissions is enhanced 5-50% above the emitted ratios at times and locations of aircraft measurements. We also find a correlation between ambient formaldehyde concentrations and measured ΔCO:ΔNO _y suggesting that secondary CO formation plays a role in these elevated ratios. This analysis suggests that ambient urban daytime ΔCO:ΔNO _y values are not reflective of emitted ratios from individual sources.

Characterizing the impact of projected changes in climate and air quality on human exposures to ozone

The impact of climate change on human and environmental health is of critical concern. Population exposures to air pollutants both indoors and outdoors are influenced by a wide range of air quality, meteorological, behavioral, and housing-related factors, many of which are also impacted by climate change. An integrated methodology for modeling changes in human exposures to tropospheric ozone (O₃) owing to potential future changes in climate and demographics was implemented by linking existing modeling tools for climate, weather, air quality, population distribution, and human exposure. Human exposure results from the Air Pollutants Exposure Model (APEX) for 12 US cities show differences in daily maximum 8-h (DM8H) exposure patterns and levels by sex, age, and city for all scenarios. When climate is held constant and population demographics are varied, minimal difference in O₃ exposures is predicted even with the most extreme demographic change scenario. In contrast, when population is held constant, we see evidence of substantial changes in O₃ exposure for the most extreme change in climate. Similarly, we see increases in the percentage of the population in each city with at least one O₃ exposure exceedance above 60 p.p.b and 70 p.p.b thresholds for future changes in climate. For these climate and population scenarios, the impact of projected changes in climate and air quality on human exposure to O₃ are much larger than the impacts of changing demographics. These results indicate the potential for future changes in O₃ exposure as a result of changes in climate that could impact human health.

Description and evaluation of the Community Multiscale Air Quality (CMAQ) modeling system version 5.1

The Community Multiscale Air Quality (CMAQ) model is a comprehensive multipollutant air quality modeling system developed and maintained by the US Environmental Protection Agency's (EPA) Office of Research and Development (ORD). Recently, version 5.1 of the CMAQ model (v5.1) was released to the public, incorporating a large number of science updates and extended capabilities over the previous release version of the model (v5.0.2). These updates include the following: improvements in the meteorological calculations in both CMAQ and the Weather Research and Forecast (WRF) model used to provide meteorological fields to CMAQ, updates to the gas and aerosol chemistry, revisions to the calculations of clouds and photolysis, and improvements to the dry and wet deposition in the model. Sensitivity simulations isolating several of the major updates to the modeling system show that changes to the meteorological calculations result in enhanced afternoon and early evening mixing in the model, periods when the model historically underestimates mixing. This enhanced mixing results in higher ozone (O₃) mixing ratios on average due to reduced NO titration, and lower fine particulate matter (PM_2.5) concentrations due to greater dilution of primary pollutants (e.g., elemental and organic carbon). Updates to the clouds and photolysis calculations greatly improve consistency between the WRF and CMAQ models and result in generally higher O₃ mixing ratios, primarily due to reduced cloudiness and attenuation of photolysis in the model. Updates to the aerosol chemistry result in higher secondary organic aerosol (SOA) concentrations in the summer, thereby reducing summertime PM_2.5 bias (PM_2.5 is typically underestimated by CMAQ in the summer), while updates to the gas chemistry result in slightly higher O₃ and PM_2.5 on average in January and July. Overall, the seasonal variation in simulated PM_2.5 generally improves in CMAQv5.1 (when considering all model updates), as simulated PM_2.5 concentrations decrease in the winter (when PM_2.5 is generally overestimated by CMAQ) and increase in the summer (when PM_2.5 is generally underestimated by CMAQ). Ozone mixing ratios are higher on average with v5.1 vs. v5.0.2, resulting in higher O₃ mean bias, as O₃ tends to be overestimated by CMAQ throughout most of the year (especially at locations where the observed O₃ is low); however, O₃ correlation is largely improved with v5.1. Sensitivity simulations for several hypothetical emission reduction scenarios show that v5.1 tends to be slightly more responsive to reductions in NO _x (NO + NO₂), VOC and SO _x (SO₂ + SO₄) emissions than v5.0.2, representing an improvement as previous studies have shown CMAQ to underestimate the observed reduction in O₃ due to large, widespread reductions in observed emissions.

Description and evaluation of the Community Multiscale Air Quality (CMAQ) modeling system version 5.1

The Community Multiscale Air Quality (CMAQ) model is a comprehensive multipollutant air quality modeling system developed and maintained by the US Environmental Protection Agency's (EPA) Office of Research and Development (ORD). Recently, version 5.1 of the CMAQ model (v5.1) was released to the public, incorporating a large number of science updates and extended capabilities over the previous release version of the model (v5.0.2). These updates include the following: improvements in the meteorological calculations in both CMAQ and the Weather Research and Forecast (WRF) model used to provide meteorological fields to CMAQ, updates to the gas and aerosol chemistry, revisions to the calculations of clouds and photolysis, and improvements to the dry and wet deposition in the model. Sensitivity simulations isolating several of the major updates to the modeling system show that changes to the meteorological calculations result in enhanced afternoon and early evening mixing in the model, periods when the model historically underestimates mixing. This enhanced mixing results in higher ozone (O₃) mixing ratios on average due to reduced NO titration, and lower fine particulate matter (PM_2.5) concentrations due to greater dilution of primary pollutants (e.g., elemental and organic carbon). Updates to the clouds and photolysis calculations greatly improve consistency between the WRF and CMAQ models and result in generally higher O₃ mixing ratios, primarily due to reduced cloudiness and attenuation of photolysis in the model. Updates to the aerosol chemistry result in higher secondary organic aerosol (SOA) concentrations in the summer, thereby reducing summertime PM_2.5 bias (PM_2.5 is typically underestimated by CMAQ in the summer), while updates to the gas chemistry result in slightly higher O₃ and PM_2.5 on average in January and July. Overall, the seasonal variation in simulated PM_2.5 generally improves in CMAQv5.1 (when considering all model updates), as simulated PM_2.5 concentrations decrease in the winter (when PM_2.5 is generally overestimated by CMAQ) and increase in the summer (when PM_2.5 is generally underestimated by CMAQ). Ozone mixing ratios are higher on average with v5.1 vs. v5.0.2, resulting in higher O₃ mean bias, as O₃ tends to be overestimated by CMAQ throughout most of the year (especially at locations where the observed O₃ is low); however, O₃ correlation is largely improved with v5.1. Sensitivity simulations for several hypothetical emission reduction scenarios show that v5.1 tends to be slightly more responsive to reductions in NO _x (NO + NO₂), VOC and SO _x (SO₂ + SO₄) emissions than v5.0.2, representing an improvement as previous studies have shown CMAQ to underestimate the observed reduction in O₃ due to large, widespread reductions in observed emissions.

Description and evaluation of the Community Multiscale Air Quality (CMAQ) modeling system version 5.1

The Community Multiscale Air Quality (CMAQ) model is a comprehensive multipollutant air quality modeling system developed and maintained by the US Environmental Protection Agency's (EPA) Office of Research and Development (ORD). Recently, version 5.1 of the CMAQ model (v5.1) was released to the public, incorporating a large number of science updates and extended capabilities over the previous release version of the model (v5.0.2). These updates include the following: improvements in the meteorological calculations in both CMAQ and the Weather Research and Forecast (WRF) model used to provide meteorological fields to CMAQ, updates to the gas and aerosol chemistry, revisions to the calculations of clouds and photolysis, and improvements to the dry and wet deposition in the model. Sensitivity simulations isolating several of the major updates to the modeling system show that changes to the meteorological calculations result in enhanced afternoon and early evening mixing in the model, periods when the model historically underestimates mixing. This enhanced mixing results in higher ozone (O₃) mixing ratios on average due to reduced NO titration, and lower fine particulate matter (PM_2.5) concentrations due to greater dilution of primary pollutants (e.g., elemental and organic carbon). Updates to the clouds and photolysis calculations greatly improve consistency between the WRF and CMAQ models and result in generally higher O₃ mixing ratios, primarily due to reduced cloudiness and attenuation of photolysis in the model. Updates to the aerosol chemistry result in higher secondary organic aerosol (SOA) concentrations in the summer, thereby reducing summertime PM_2.5 bias (PM_2.5 is typically underestimated by CMAQ in the summer), while updates to the gas chemistry result in slightly higher O₃ and PM_2.5 on average in January and July. Overall, the seasonal variation in simulated PM_2.5 generally improves in CMAQv5.1 (when considering all model updates), as simulated PM_2.5 concentrations decrease in the winter (when PM_2.5 is generally overestimated by CMAQ) and increase in the summer (when PM_2.5 is generally underestimated by CMAQ). Ozone mixing ratios are higher on average with v5.1 vs. v5.0.2, resulting in higher O₃ mean bias, as O₃ tends to be overestimated by CMAQ throughout most of the year (especially at locations where the observed O₃ is low); however, O₃ correlation is largely improved with v5.1. Sensitivity simulations for several hypothetical emission reduction scenarios show that v5.1 tends to be slightly more responsive to reductions in NO _x (NO + NO₂), VOC and SO _x (SO₂ + SO₄) emissions than v5.0.2, representing an improvement as previous studies have shown CMAQ to underestimate the observed reduction in O₃ due to large, widespread reductions in observed emissions.

Description and evaluation of the Community Multiscale Air Quality (CMAQ) modeling system version 5.1

The Community Multiscale Air Quality (CMAQ) model is a comprehensive multipollutant air quality modeling system developed and maintained by the US Environmental Protection Agency's (EPA) Office of Research and Development (ORD). Recently, version 5.1 of the CMAQ model (v5.1) was released to the public, incorporating a large number of science updates and extended capabilities over the previous release version of the model (v5.0.2). These updates include the following: improvements in the meteorological calculations in both CMAQ and the Weather Research and Forecast (WRF) model used to provide meteorological fields to CMAQ, updates to the gas and aerosol chemistry, revisions to the calculations of clouds and photolysis, and improvements to the dry and wet deposition in the model. Sensitivity simulations isolating several of the major updates to the modeling system show that changes to the meteorological calculations result in enhanced afternoon and early evening mixing in the model, periods when the model historically underestimates mixing. This enhanced mixing results in higher ozone (O3) mixing ratios on average due to reduced NO titration, and lower fine particulate matter (PM2.5) concentrations due to greater dilution of primary pollutants (e.g., elemental and organic carbon). Updates to the clouds and photolysis calculations greatly improve consistency between the WRF and CMAQ models and result in generally higher O3 mixing ratios, primarily due to reduced cloudiness and attenuation of photolysis in the model. Updates to the aerosol chemistry result in higher secondary organic aerosol (SOA) concentrations in the summer, thereby reducing summertime PM2.5 bias (PM2.5 is typically underestimated by CMAQ in the summer), while updates to the gas chemistry result in slightly higher O3 and PM2.5 on average in January and July. Overall, the seasonal variation in simulated PM2.5 generally improves in CMAQv5.1 (when considering all model updates), as simulated PM2.5 concentrations decrease in the winter (when PM2.5 is generally overestimated by CMAQ) and increase in the summer (when PM2.5 is generally underestimated by CMAQ). Ozone mixing ratios are higher on average with v5.1 vs. v5.0.2, resulting in higher O3 mean bias, as O3 tends to be overestimated by CMAQ throughout most of the year (especially at locations where the observed O3 is low); however, O3 correlation is largely improved with v5.1. Sensitivity simulations for several hypothetical emission reduction scenarios show that v5.1 tends to be slightly more responsive to reductions in NO x (NO + NO2), VOC and SO x (SO2 + SO4) emissions than v5.0.2, representing an improvement as previous studies have shown CMAQ to underestimate the observed reduction in O3 due to large, widespread reductions in observed emissions.

A spectral method for spatial downscaling

Complex computer models play a crucial role in air quality research. These models are used to evaluate potential regulatory impacts of emission control strategies and to estimate air quality in areas without monitoring data. For both of these purposes, it is important to calibrate model output with monitoring data to adjust for model biases and improve spatial prediction. In this article, we propose a new spectral method to study and exploit complex relationships between model output and monitoring data. Spectral methods allow us to estimate the relationship between model output and monitoring data separately at different spatial scales, and to use model output for prediction only at the appropriate scales. The proposed method is computationally efficient and can be implemented using standard software. We apply the method to compare Community Multiscale Air Quality (CMAQ) model output with ozone measurements in the United States in July 2005. We find that CMAQ captures large-scale spatial trends, but has low correlation with the monitoring data at small spatial scales.

Sensitivity of continental United States atmospheric budgets of oxidized and reduced nitrogen to dry deposition parametrizations

Reactive nitrogen (Nr) is removed by surface fluxes (air-surface exchange) and wet deposition. The chemistry and physics of the atmosphere result in a complicated system in which competing chemical sources and sinks exist and impact that removal. Therefore, uncertainties are best examined with complete regional chemical transport models that simulate these feedbacks. We analysed several uncertainties in regional air quality model resistance analogue representations of air-surface exchange for unidirectional and bi-directional fluxes and their effect on the continental Nr budget. Model sensitivity tests of key parameters in dry deposition formulations showed that uncertainty estimates of continental total nitrogen deposition are surprisingly small, 5 per cent or less, owing to feedbacks in the chemistry and rebalancing among removal pathways. The largest uncertainties (5%) occur with the change from a unidirectional to a bi-directional NH3 formulation followed by uncertainties in bi-directional compensation points (1-4%) and unidirectional aerodynamic resistance (2%). Uncertainties have a greater effect at the local scale. Between unidirectional and bi-directional formulations, single grid cell changes can be up to 50 per cent, whereas 84 per cent of the cells have changes less than 30 per cent. For uncertainties within either formulation, single grid cell change can be up to 20 per cent, but for 90 per cent of the cells changes are less than 10 per cent.

[The estimation of the i.m. morphine-equivalent in cancer pain treatment with different opioids or different routes of administrations. Practical meaning and limitations.]

During the long-term treatment with opioids it is sometimes important to switch the opioid or change the route of administration. The estimation of morphine-equivalents can be helpful in this range because it clarifies the dose in milligramm required for different clinical situations. The basis of this estimation is the equianalgesic potency of opioids. One i.m. morphine-equivalent is the analgesic dose of an opioid (i.m. injected) equal to the analgesic effect of 1 mg morphine (i.m.). The relationships between equianalgesic doses and intramuscular and oral routes of applications are listed in tables. The cross-tolerance between different opioids during long-term treatment is not complete. To avoid an overdose, we suggest a reduction in the calculated opioid dose of 50%. Additional "rescue doses" can be used during the period immediately the change to provied satisfactory pain control. A new opioid dosage should be calculated every 24 hours based on the basaline dose plus the total quantity of "rescue" medication required by the patient. Useful starting point for calculation an effective dose when changing from one opioid or route of administration to another can result in improved pain control that is more responsive to patient need. The limitations are 1. individual differences in the response to opioids, especially during long-term treatment and in the development of analgesic tolerance, 2. individual differences in the response to alternatives routes of administration, and 3. the unknown degree of cross tolerance among opioid drugs. The scientific meaning of the estimation of i.m. morphine-equivalent is discussed.

Bayesian analysis of a reduced-form air quality model

Numerical air quality models are being used for assessing emission control strategies for improving ambient pollution levels across the globe. This paper applies probabilistic modeling to evaluate the effectiveness of emission reduction scenarios aimed at lowering ground-level ozone concentrations. A Bayesian hierarchical model is used to combine air quality model output and monitoring data in order to characterize the impact of emissions reductions while accounting for different degrees of uncertainty in the modeled emissions inputs. The probabilistic model predictions are weighted based on population density in order to better quantify the societal benefits/disbenefits of four hypothetical emission reduction scenarios in which domain-wide NO(x) emissions from various sectors are reduced individually and then simultaneously. Cross validation analysis shows the statistical model performs well compared to observed ozone levels. Accounting for the variability and uncertainty in the emissions and atmospheric systems being modeled is shown to impact how emission reduction scenarios would be ranked, compared to standard methodology.

A comparison of statistical techniques for combining modeled and observed concentrations to create high-resolution ozone air quality surfaces

Air quality surfaces representing pollutant concentrations across space and time are needed for many applications, including tracking trends and relating air quality to human and ecosystem health. The spatial and temporal characteristics of these surfaces may reveal new information about the associations between emissions, pollution levels, and human exposure and health outcomes that may not have been discernable before. This paper presents four techniques, ranging from simple to complex, to statistically combine observed and modeled daily maximum 8-hr ozone concentrations for a domain covering the greater New York State area for the summer of 2001. Cross-validation results indicate that, for the domain and time period studied, the simpler techniques (additive and multiplicative bias adjustment) perform as well as or better than the more complex techniques. However, the spatial analyses of the resulting ozone concentration surfaces revealed some problems with these simpler techniques in limited areas where the model exhibits difficulty in simulating the complex features such as those observed in the New York City area.

Combat-related guilt mediates the relations between exposure to combat-related abusive violence and psychiatric diagnoses

BACKGROUND

This study examined the degree to which combat-related guilt mediated the relations between exposure to combat-related abusive violence and both Posttraumatic Stress Disorder (PTSD) and Major Depressive Disorder (MDD) in Vietnam Veterans.

METHODS

Secondary analyses were conducted on data collected from 1,323 male Vietnam Veterans as part of a larger, multisite study.

RESULTS

Results revealed that combat-related guilt partially mediated the association between exposure to combat-related abusive violence and PTSD, but completely mediated the association with MDD, with overall combat exposure held constant in the model. Follow-up analyses showed that, when comparing those participants who actually participated in combat-related abusive violence with those who only observed it, combat-related guilt completely mediated the association between participation in abusive violence and both PTSD and MDD. Moreover, when comparing those participants who observed combat-related abusive violence with those who had no exposure at all to it, combat-related guilt completely mediated the association between observation of combat-related abusive violence and MDD, but only partially mediated the association with PTSD.

CONCLUSIONS

These findings suggest that guilt may be a mechanism through which abusive violence is related to PTSD and MDD among combat-deployed Veterans. These findings also suggest the importance of assessing abusive-violence related guilt among combat-deployed Veterans and implementing relevant interventions for such guilt whenever indicated.

Efficient probabilistic estimates of surface ozone concentration using an ensemble of model configurations and direct sensitivity calculations

Because all models are a simplification of the phenomenon they aim to represent, it is often more useful to estimate the probability of an event rather than a single "best" model result. Previous air quality ensemble approaches have used computationally expensive simulations of separately developed modeling systems. We present an efficient method to generate ensembles with hundreds of members based on several structural configurations of a single air quality modeling system. We use the Decoupled Direct Method in three dimensions to directly calculate how ozone concentrations change as a result of changes in input parameters. The modeled probability estimate is compared to observations and is shown to have a high level of skill and improved resolution and sharpness. This approach can help resolve the practical limits of incorporating uncertainty estimation into deterministic air quality management modeling applications.

Symptom assessment and management

This article reviews how to assess and manage several symptoms commonly encountered by neurologists who care for patients with advanced illness. Scientifically validated guidelines are reviewed and practical advice is offered on how to manage pain, nausea and vomiting, dyspnea, and respiratory secretions at the end of life. The role of the neurologist as a provider of end of life care is discussed including suggestions for communicating with patients and families. This article concludes with a review of when sedation may be offered within the purview of good palliative care to patients who are imminently dying.

Palliative care in neurology

This article defines the evolving role of the neurologist as a provider of palliative care. As neurologists care for chronically and critically ill, dying patients, and individuals whose diseases are incurable at the time of diagnosis, clinical competence requires expertise in the principles and practice of palliative medicine. Multiple studies suggest that despite available guidelines many patients with neurological disease suffer from pain, dyspnea, and other symptoms at or near the end of life. Recommendations from the American Academy of Neurology and Institute of Medicine are provided and the many ongoing educational efforts aimed at closing the existing gap in knowledge and improving patient care are reviewed.

Tuberculin skin testing of physicians at a midwestern teaching hospital: a 6-year prospective study

The epidemiology of tuberculin reactivity among physicians practicing in regions of moderate tuberculosis prevalence is unknown. We prospectively assessed the epidemiology of tuberculin skin test (TST) reactivity among physicians in training in St. Louis between 1992 and 1998. Of 1574 physicians who were tested, 267 (17%) had positive TST results. Older age, birth outside of the United States, prior bacille Calmette-Guérin (BCG) vaccination, and practice in the fields of medicine, anesthesiology, or psychiatry were associated with a positive TST result. Among physicians born in the United States, 63 (5.7%) had positive TST results. Among physicians with > or = 2 documented TSTs, 12 had conversion to a positive TST (1.6%; 1.03 conversions per 100 person-years). Physicians in this study had a high rate of tuberculin reactivity, despite a low conversion rate. The relationship between TST conversion and birth outside of the United States and BCG vaccination suggests a booster phenomenon rather than true new TST conversions.

Attitudes and practices among pediatric oncologists regarding end-of-life care: results of the 1998 American Society of Clinical Oncology survey

PURPOSE

In 1998, the American Society of Clinical Oncology (ASCO) surveyed its membership to assess the attitudes, practices, and challenges associated with end-of-life care of patients with cancer. In this report, we summarize the responses of pediatric oncologists and the implications for care of children dying from cancer.

METHODS

The survey consisted of 118 questions, covering eight categories. All ASCO members in the United States, Canada, and the United Kingdom were mailed a survey, which was completed by 228 pediatric oncologists. Predictors of particular attitudes and practices were identified using stepwise logistic regression analysis. Potential predictors were age, sex, religious affiliation, importance of religious beliefs, recent death of a relative, specialty, type of practice (rural or urban, academic or nonacademic), amount of time spent in patient care, number of new patients in the past 6 months, and number of patients who died in the past year.

RESULTS

Pediatric oncologists reported a lack of formal courses in pediatric palliative care, a strikingly high reliance on trial and error in learning to care for dying children, and a need for strong role models in this area. The lack of an accessible palliative care team or pain service was often identified as a barrier to good care. Communication difficulties exist between parents and oncologists, especially regarding the shift to end-of-life care and adequate pain control.

CONCLUSION

Pediatric oncologists are working to integrate symptom control, psychosocial support, and palliative care into the routine care of the seriously ill child, although barriers exist that make such comprehensive care a challenge.

Controlling cancer pain

More than a third of patients undergoing therapy for cancer and 60% to 90% of those with advanced malignancy report significant pain. Effective analgesic therapy is available, yet large segments of this population--in particular, elderly patients in nursing homes, minorities, and women--receive inadequate palliative therapy.

End-of-life care: a survey of US neurologists' attitudes, behavior, and knowledge

OBJECTIVE

The American Academy of Neurology (AAN) surveyed the attitudes, behavior, and knowledge of its members regarding care at the end of life. Three groups of AAN members were surveyed: neuro-oncologists, ALS specialists, and a representative sample of US neurologists.

METHODS

The survey presented two clinical scenarios involving end-of-life care. Neurologists were asked a series of questions to assess their knowledge of existing medical, ethical, and legal guidelines; their willingness to participate in physician-assisted suicide (PAS) or carry out voluntary euthanasia (VE); and their general attitudes regarding end-of-life care.

RESULTS

Neurologists support a patient's right to refuse life-sustaining treatment, but many believe that they are killing their patients in supporting such refusals. Thirty-seven percent think it is illegal to administer analgesics in doses that risk respiratory depression to the point of death. Forty percent believe they should obtain legal counsel when considering stopping life-sustaining treatment. One half believe that PAS should be made explicitly legal by statute for terminally ill patients. Under current law, 13% would participate in PAS and 4% would carry out VE; if those procedures were legalized, 44% would participate in PAS and 28% in VE. Approximately one third believe that physicians have the same ethical duty to honor a terminally ill patient's request for PAS as they do to honor a such a patient's refusal of life-sustaining therapy.

CONCLUSIONS

There is a gap between established medical, legal, and ethical guidelines for the care of dying patients and the beliefs and practices of many neurologists, suggesting a need for graduate and postgraduate education programs in the principles and practices of palliative care medicine. Many neurologists would participate in PAS and carry out VE if legalized.

Advances in cancer pain

Advances in cancer pain research and management are an example of the advances that have occurred within the field of neuro-oncology, the medical discipline that includes the diagnosis and treatment of primary central nervous system neoplasms, metastatic and nonmetastatic neurological complications of cancer originating outside the nervous system, and pain associated with cancer. Progress in the diagnosis and treatment of cancer, coupled with advances in our understanding of the anatomy, physiology, pharmacology, and psychology of pain perception, has led to improved care of the patient with pain of malignant origin. Currently, specialized methods of cancer diagnosis and treatment provide the most direct approach to treating cancer pain by treating the cause of the pain. Yet, before the introduction of successful antitumor therapy, when treatment of the cause of the pain has failed or when injury to bone, soft tissue, or nerve has occurred as a result of therapy, appropriate pain management is essential.

Pain and the barriers to its relief at the end of life: a lesson for improving end of life health care

Pain among cancer patients is a common distressing symptom that frequently affects physical functioning, social interaction, psychological status, and quality of life. Despite the extensive body of knowledge available regarding cancer pain assessment and management, it often remains untreated, thereby diminishing the quality of patient care at the end of life. Recommendations on how to remove these barriers, as well as to improve care of the dying in general, need to be implemented by the U.S. government.

Determinants of the willingness to endorse assisted suicide. A survey of physicians, nurses, and social workers

The authors surveyed 1,137 physicians, nurses, and social workers (overall response = 48%) to characterize the willingness to endorse assisted suicide. Willingness to endorse varied among disciplines and was negatively correlated with level of religious belief (r = -0.35, P < 0.0001), knowledge of symptom management (r = -0.21, P < 0.0001), and time managing symptoms (r = -0.21, P < 0.0001). On multivariate analysis, the significant predictors were lesser religious belief (P < 0.0001), greater concern about analgesic toxicity (P = 0.001), diminished empathy (P = 0.03), lesser knowledge of symptom management (P < 0.04), and the interaction between religious belief and knowledge of symptom management (P = 0.04). Professionals' attitudes toward assisted suicide are influenced by diverse personal attributes, among which may be competence in symptom management and burnout.

A peaceful death: how to manage pain and provide quality care. A roundtable discussion: Part 2

One of the most important components of a peaceful death is adequate control of pain and other distressing symptoms, such as dyspnea, agitation, and restlessness. Pain is an important symptom in 75 to 80% of noncancer patients in the last year of life. Opioid analgesics are often the mainstay of pain treatment for dying patients. A primary care physician also needs to know about anesthetic and neurosurgical approaches, the use of cognitive behavioral approaches, and the availability of specialized pain experts. A sizeable minority of physicians receive requests for an assisted death, which should be seen as a cry for help. The most useful function of advance directives is that they open an avenue for discussion between the doctor and the patient about a difficult subject.

Palliative medicine: providing care when cure is not possible. A roundtable discussion: Part I

Palliative medicine describes the care of patients with advanced disease. When cure is no longer possible, the goal becomes control of pain, other symptoms, and psychological distress. In the United States, palliation has been pioneered by the hospice movement for patients with disseminated cancer and AIDS. Palliative care is also appropriate for patients with many of the chronic diseases of aging. For medical, humanitarian, financial, and legal reasons, physicians are being called on to provide palliative care when they make the diagnosis of all illness that is unresponsive to curative treatment.

Guidelines in the care of the dying cancer patient

The care of patients in the final stages of cancer requires a high level of clinical vigilance and skill to ensure that the passage from life to death is as free from suffering as possible. Patients who are dying have a right to adequate relief of physical and psychological symptoms, and they and their families have a right to adequate support. The care of patients and their families requires (1) interdisciplinary cooperation of a healthcare team incorporating physicians, nurses, social workers, and other auxiliary supports, and (2) a high level of clinical flexibility to address the evolving needs of the patient and family. Participation in this process challenges the clinician's emotional resources and medical skills. There is, however, the potential for professional satisfaction in helping to orchestrate a "good death," because the relief of suffering is at the very heart of medicine. Familiarity with guidelines in the care of the dying can reduce the potential for distress in this important clinical endeavor.

Dextromethorphan shows efficacy in experimental pain (nociception) and opioid tolerance

The oral antitussive dextromethorphan is a clinically available N-methyl-D-aspartate receptor antagonist. Dextromethorphan has analgesic efficacy in the experimental formalin test, blocks the nociceptive activation of the immediate-early gene, c-fos proto-oncogene, and prevents and reverses the development of opiate analgesic tolerance in experimental models. These data suggest that dextromethorphan should be evaluated in a controlled clinical trial for analgesic efficacy in zoster-associated neuralgia.

Opioid pharmacotherapy in the management of cancer pain: a survey of strategies used by pain physicians for the selection of analgesic drugs and routes of administration

BACKGROUND

This survey documents the strategies used by pain control physicians in the selection of opioid drugs and routes of administration in the management of inpatients referred to a cancer pain service.

METHODS

The following approaches were prospectively evaluated during the treatment of 100 consecutive inpatients: 1) the influence of the evaluation of the goals of care on decision making, 2) selection of opioid drugs, 3) indications for changing opioid drugs and the frequency with which this strategy is used, and 4) selection of route of administration.

RESULTS

Eighty of the 100 patients underwent a total of 182 changes in drug, route, or both drug and route before discharge or death. The major reasons for change were to improve the convenience of treatment regimen in the setting of adequate pain relief (31.4%), diminish side effects in the setting of controlled pain (25.0%), reduce the invasiveness of therapy in the setting of controlled pain (19.3%), and simultaneously improve pain control and reduce opioid toxicity (17.7%). When opioid toxicity was the reason for change, physicians changed the opioid drug in 71% of cases and the route in 29%. When convenience or invasiveness were targeted, the physicians changed the route in 61% of cases and the opioid in 39%. Forty-four patients required one or more change in the opioid, and 20 required 2 or more changes (range, 2-6 changes). At the time of discharge (n = 82), morphine was more commonly selected than hydromorphone or fentanyl (39% vs. 23% vs. 17%) and the routes of administration were oral (57%), transdermal (18%), intravenous (18%), subcutaneous (5%), and intraspinal (4%). Therapeutic changes were associated with improvement in physician-recorded pain intensity and a lower prevalence of cognitive impairment, hallucinations, nausea and vomiting, and myoclonus among patients who were discharged from the hospital.

CONCLUSIONS

These data illustrate the application of strategies for selections of opioid drugs and their route of administration that are recommended in current guidelines for the management of cancer pain.

Misconceptions and controversies regarding the use of opioids in cancer pain

The WHO has created a Cancer Pain Relief Programme and developed guidelines for the treatment of cancer pain. Implementation of the analgesic guidelines, assurance of drug availability (specifically opioids), education of healthcare professionals, and designating cancer pain as a priority for all national cancer control programmes are the major goals. Recent studies of medical students, physicians, nurses and state medical boards demonstrate a significant lack of knowledge with regard to the theoretical and practical understanding of the use of analgesic drugs, particularly opioids, in the management of cancer pain. Communication between physicians and patients about pain symptoms has also been shown to be problematic. Limited availability of opioids, their excessive regulation, and the lack of use of alternatives to systemic analgesics also prevent adequate management. Although analgesic drug therapy is the mainstay of treatment, opioid use remains a controversial issue. Some of the controversies include their role in the management of neuropathic pain, which has been suggested to be 'opioid-resistant', as well as the choice of opioid drug. A third controversy is the route of administration. The impetus for the development of novel routes has come from the goals of maximising analgesia, minimising side effects, and providing convenient dosing schedules for patients who require parenteral administration. Other important controversial issues are the development of tolerance and the relationship of pain management to patient requests for physician-assisted suicide and euthanasia.

Pain and depression in patients with newly diagnosed pancreas cancer

PURPOSE

To evaluate the prevalence of pain and depression, their correlation, and their effect on quality of life in patients with recently diagnosed adenocarcinoma of the pancreas (PC).

MATERIALS AND METHODS

Cross-sectional pain and psychosocial distress were assessed using validated instruments, including the Memorial Pain Assessment Card (MPAC), Beck Depression Inventory (BDI), Hopelessness Scale (BHS), and Functional Living Index-Cancer (FLIC). Patients were evaluated before their first operation for PC or first treatment with chemotherapy at a large tertiary-care cancer center.

RESULTS

One hundred thirty patients with proven PC were studied: 83 before their operation and 47 before their first chemotherapy treatment. At the time of study entrance, 37% of patients had no pain and an additional 34% had pain that was mild or less severe. Only 29% of patients had moderate, strong, or severe pain. Chemotherapy patients reported significantly more intense pain than did preoperative patients (P = .02). Symptoms of depression were assessed using the BDI and BHS scales. A substantial minority of patients (38%) had BDI scores > or = 15, which suggests high levels of depressive symptoms. There was a significant correlation between increasing pain and depressive symptoms among those who experienced pain. Quality of life was assessed using the Weekly Activity Checklist (WAC) and the FLIC. Compared with patients who had no pain or mild pain, patients with moderate or greater pain had significantly impaired functional activity (P = .03) and poorer quality-of-life scores (P = .02) when compared with those with lesser degrees of pain. There were significant correlations between increasing pain and depression and between pain and depressive symptoms and impaired quality of life and function.

CONCLUSION

Our results indicate that moderate or severe pain and symptoms of depression are not as prevalent in recently diagnosed PC patients as is generally believed. However, one third have inadequate pain control despite the use of oral analgesics. These patients can be identified by the use of a simple self-report instrument (the MPAC card). Quality of life and function are adversely affected by moderate or greater levels of perceived pain intensity. A simple and rapid assessment is possible and can identify high-risk patients in need of intervention that may improve quality of life.

Therapeutic and neurotoxic effects of 2-chlorodeoxyadenosine in adults with acute myeloid leukemia

Despite expectations that 2-chlorodeoxyadenosine (2-CdA) would prove active primarily in lymphoproliferative diseases, early reports suggested unexpected high activity of this drug in heavily pretreated children with acute myeloblastic leukemia (AML) at a maximally tolerated dose of 8.9 mg/m2/day for 5 days. In view of these findings, we conducted an escalating dose trial of 2-CdA in adult patients with relapsed or resistant AML. Thirty-six patients who had received extensive prior therapy were treated at 9 dose levels of 2-CdA at daily doses ranging from 5 to 21 mg/m2 for 5 days. 2-CdA eliminated leukemic blasts from the peripheral blood in 32 of 36 cases; however, bone marrow hypoplasia was seen only at daily dose levels > or = 15 mg/m2. We observed a total of 3 complete remissions: 1 at the 15 mg/m2/d dose level and 2 at the 21 mg/m2/d dose level; these responses persisted for 3, 2, and 3 months, respectively. Although prolonged myelosuppression would have been dose-limiting at 21 mg/m2/d for 5 days, the most important adverse effect was the development of a sensorimotor peripheral neuropathy. This reaction, whose onset was substantially delayed after completion of drug treatment, was observed in 2 of 5 patients at the 19 mg/m2/d level and in 4 of 4 evaluable patients at the 21 mg/m2/d level. Pathologically, this process was characterized by axonal degeneration and secondary demyelination. Other side effects included reactivation of a posttransplant Epstein-Barr virus-related lymphoma in 1 patient and tumor lysis syndrome. We conclude that the maximally tolerable dose of 2-CdA in adult patients (17 mg/m2/d for 5 days) in approximately twofold in excess of that previously reported in children and that the limiting toxic effect is a degenerative neuropathic disorder. We confirm that this drug has definite activity in AML, but the magnitude of this effect needs to be determined in larger numbers of patients who have received less extensive therapy. This agent deserves further evaluation in patients with both AML and acute lymphoblastic leukemia at these higher doses and perhaps as part of a preparative regimen for patients undergoing bone marrow transplantation.