Sampling artifacts from the use of denuder tubes with glycerol based coatings in the measurement of atmospheric particulate matter.

Chemical speciation studies use sampling configurations that often require the deployment of denuder tubes of various types to measure certain species or control particulate sampling artifacts. Concurrent sets of measurements on Teflon membrane and quartz filters in specific sampling configurations were used to evaluate the potential influence of denuder tubes with glycerol-based coatings on particulate mass and carbon measurements on downstream filters. Positive biases were observed in the measurement of gravimetric mass and carbon on Teflon and quartz filters, respectively, downstream of sodium carbonate/ glycerol and citric acid/glycerol coated denuder tubes relative to those without upstream denuder tubes. The magnitude of the bias is dependent on the level of ambient particulate loading.

Windblown dust contributes to high PM2.5 concentrations.

The revised National Ambient Air Quality Standards for PM include fine particulate standards based upon mass measurements of PM2.5. It is possible in arid and semi-arid regions to observe significant coarse mode intrusion in the PM2.5 measurement. In this work, continuous PM10, PM2.5, and PM1.0 were measured during several windblown dust events in Spokane, WA. PM2.5 constituted approximately 30% of the PM10 during the dust event days, compared with approximately 48% on the non-dusty days preceding the dust events. Both PM10 and PM2.5 were enhanced during the dust events. However, PM1.0 was not enhanced during dust storms that originated within the state of Washington. During a dust storm that originated in Asia and impacted Spokane, PM1.0 was also enhanced, although the Asian dust reached Washington during a period of stagnation and poor dispersion, so that local sources were also contributing to high particulate levels. The "intermodal" region of PM, defined as particles ranging in aerodynamic size from 1.0 to 2.5 microns, was found to represent a significant fraction of PM2.5 (approximately 51%) during windblown dust events, compared with 28% during the non-dusty days before the dust events.

Asthma aggravation, combustion, and stagnant air.

BACKGROUND: The relationship between current concentrations of ambient air pollution and adverse health effects is controversial. We report a meteorological index of air stagnation that is associated with daily visits to the emergency department for asthma in two urban areas. METHODS: Data on daily values of a stagnation persistence index and visits to the emergency department for asthma were collected for approximately two years in Spokane, Washington, USA and for 15 months in Seattle, Washington, USA. The stagnation persistence index represents the number of hours during the 24 hour day when surface wind speeds are less than the annual hourly median value, an index readily available for most urban areas. Associations between the daily stagnation persistence index and daily emergency department visits for asthma were tested using a generalised additive Poisson regression model. A factor analysis of particulate matter (PM(2.5)) composition was performed to identify the pollutants associated with increased asthma visits. RESULTS: The relative rate of the association between a visit to the emergency department for asthma and the stagnation persistence index was 1. 12 (95% CI 1.05 to 1.19) in Spokane and 1.21 (95% CI 1.09 to 1.35) in Seattle for an increase of 11 and 10 hours, respectively, of low wind speed in a given day. The stagnation persistence index was only correlated with one set of factor loadings; that cluster included the stagnation persistence index, carbon monoxide, and organic/elemental carbon. CONCLUSION: Increased air stagnation was shown to be a surrogate for accumulation of the products of incomplete combustion, including carbon monoxide and fine particulate levels of organic and elemental carbon, and was more strongly associated with asthma aggravation than any one of the measured pollutants.

Airborne Particulate Matter Size Distributions in an Arid Urban Area.

While there is a growing body of data on the health effects of particulate matter, there is little information available from areas that experience frequent dust storms, such as Spokane, WA. As part of a three-year study to investigate the health effects associated with exposure to atmospheric aerosols, ambient particulate matter in Spokane is being characterized according to particle size and chemical composition. In this report, particulate matter concentrations measured using continuous tapered-element oscillating microbalances for three size ranges are discussed. Particles with aerodynamic diameters less than 10 micrometers (PM10), less than 2.5 micrometers (PM25), and less than 1.0 micrometer (PM1.0) were measured at a residential site; PM10 and PM2.5 were measured at an industrial site. Based upon 1.5 years of data, PM10 was found, on average, to consist of approximately 40% PM2.5 at the industrial site and approximately 50% at the residential site, with higher fractions (up to 50% at the industrial site and up to 80% at the residential site) observed in the late fall or early winter (October-November). At the residential site, PM25 was comprised of approximately 80% particles 1.0 micrometer and smaller. Only one windblown dust storm occurred during the sampling period, on July 24, 1994, during which both PM10 and PM2.5 concentrations were enhanced.

The effects of direct versus indirect hypnotic suggestion on pain in a cold pressor task.

Past studies have investigated the usefulness of hypnosis in pain reduction. Although hypnotic analgesia has been found to be effective, it is generally only those subjects who are highly susceptible to hypnosis who benefit. Some experimenters have found that even low-susceptible subjects can use hypnotic analgesia, if the hypnotic induction uses indirect rather than direct hypnotic suggestions. In the present study, high- and low-susceptible subjects were tested for analgesia using either direct or indirect hypnotic suggestion on pain in a cold pressor task. Findings suggest that high susceptibles experience greater pain reduction than do low susceptibles. However, no significant differences were found between the pain reduction in the direct versus the indirect hypnotic suggestion groups. Possible explanations for this lack of differences are discussed.

Chemical climatology of high elevation spruce-fir forests in the southern Appalachian mountains.

The physical and chemical climatology of high elevation (> 1500 m) spruce-fir forests in the southern Appalachian mountains was studied by establishing a weather and atmospheric chemical observatory at Mt Mitchell State Park in North Carolina (35 degrees 44' 05" N, 82 degrees 17' 15"W). Data collected during the summer and autumn (May-October) of 1986, 1987, and 1988 are reported. All measurements were made on or near a 16.5 m walk-up tower extending 10 m above the forest canopy on Mt Gibbes (2006 m msl), which is located approximately 2 km SW of Mt Mitchell. The tower was equipped with standard meteorological instrumentation, a passive cloud water collector, and gas pollutant sensors for O3, SO2, NOx. The tower and nearby forest canopy were immersed in clouds 25 to 40% of the time. Non-precipitating clouds were very acidic (pH 2.5-4.5). Precipitating clouds were less acidic (pH 3.5-5.5). The dominant wind directions were WNW and ESE. Clouds from the most common wind direction (WNW) were more acidic (mean pH 3.5) than those from the next most common wind direction (ESE, mean pH 5.5). Cloud water acidity was related to the concentration of SO4(2-), and NO3- ions. Mean concentration of H+, NH4+, SO4(2-), and NO3- ions in the cloud water varied from 330-340, 150-200, 190-200 and 120-140 micromol litre(-1) respectively. The average and range of O3 were 50 (25-100) ppbv (109) in 1986, 51 (26-102) ppbv in 1987, and 66 (30-140) during the 1988 field seasons, respectively. The daily maximum, 1-h average, and 24-h average concentrations were all greatest during June through mid-August, suggesting a correlation with the seasonal temperature and solar intensity. Throughfall collectors near the tower were used to obtain a useful estimate of deposition to the forest canopy. Between 50-60% of the total deposition of SO4(2-) was due to cloud impact.

Differential mood changes in alcoholics as a function of anxiety management strategies.

A study was designed to compare the effects of three relaxation strategies on mood state profiles in a group of 30 male alcoholics. The Profile of Mood States (POMS) was used for pre- and posttest treatment measures. The results indicated that the three relaxation strategies--progressive relaxation training, (PRT), meditation training (MT), quiet rest (QR)--produced qualitatively different patterns. While both PRT and MT produced measurable decrements in self-reported tension and QR controls showed no change on any of the six subscales, PRT was observed to effect decreased depression as well as a trend toward increased vigor. Meditation training effects were limited to decreased tension and a nonsignificant decrease in fatigue. These results are discussed in terms of refinement of the "relaxation response" notion to a more heterogeneous, technique-centered definition.