Exhaled Nitric Oxide in Children with Asthma and Short-Term PM(2.5) Exposure in Seattle

The objective of this study was to evaluate associations between short-term (hourly) exposures to particulate matter with aerodynamic diameters < 2.5 μm (PM(2.5)) and the fractional concentration of nitric oxide in exhaled breath (Fe(NO)) in children with asthma participating in an intensive panel study in Seattle, Washington. The exposure data were collected with tapered element oscillation microbalance (TEOM) PM(2.5) monitors operated by the local air agency at three sites in the Seattle area. Fe(NO) is a marker of airway inflammation and is elevated in individuals with asthma. Previously, we reported that offline measurements of Fe(NO) are associated with 24-hr average PM(2.5) in a panel of 19 children with asthma in Seattle. In the present study using the same children, we used a polynomial distributed lag model to assess the association between hourly lags in PM(2.5) exposure and Fe(NO) levels. Our model controlled for age, ambient NO levels, temperature, relative humidity, and modification by use of inhaled corticosteroids. We found that Fe(NO) was associated with hourly averages of PM(2.5) up to 10–12 hr after exposure. The sum of the coefficients for the lag times associated with PM(2.5) in the distributed lag model was 7.0 ppm Fe(NO). The single-lag-model Fe(NO) effect was 6.9 [95% confidence interval (CI), 3.4 to 10.6 ppb] for a 1-hr lag, 6.3 (95% CI, 2.6 to 9.9 ppb ) for a 4-hr lag, and 0.5 (95% CI, −1.1 to 2.1 ppb) for an 8-hr lag. These data provide new information concerning the lag structure between PM(2.5) exposure and a respiratory health outcome in children with asthma

Associations between Health Effects and Particulate Matter and Black Carbon in Subjects with Respiratory Disease

We measured fractional exhaled nitric oxide (FE(NO)), spirometry, blood pressure, oxygen saturation of the blood (SaO(2)), and pulse rate in 16 older subjects with asthma or chronic obstructive pulmonary disease (COPD) in Seattle, Washington. Data were collected daily for 12 days. We simultaneously collected PM(10) and PM(2.5) (particulate matter ≤10 μm or ≤2.5 μm, respectively) filter samples at a central outdoor site, as well as outside and inside the subjects’ homes. Personal PM(10) filter samples were also collected. All filters were analyzed for mass and light absorbance. We analyzed within-subject associations between health outcomes and air pollution metrics using a linear mixed-effects model with random intercept, controlling for age, ambient relative humidity, and ambient temperature. For the 7 subjects with asthma, a 10 μg/m(3) increase in 24-hr average outdoor PM(10) and PM(2.5) was associated with a 5.9 [95% confidence interval (CI), 2.9–8.9] and 4.2 ppb (95% CI, 1.3–7.1) increase in FE(NO), respectively. A 1 μg/m(3) increase in outdoor, indoor, and personal black carbon (BC) was associated with increases in FE(NO) of 2.3 ppb (95% CI, 1.1–3.6), 4.0 ppb (95% CI, 2.0–5.9), and 1.2 ppb (95% CI, 0.2–2.2), respectively. No significant association was found between PM or BC measures and changes in spirometry, blood pressure, pulse rate, or SaO(2) in these subjects. Results from this study indicate that FE(NO) may be a more sensitive marker of PM exposure than traditional health outcomes and that particle-associated BC is useful for examining associations between primary combustion constituents of PM and health outcomes

Pulmonary Effects of Indoor- and Outdoor-Generated Particles in Children with Asthma

Most particulate matter (PM) health effects studies use outdoor (ambient) PM as a surrogate for personal exposure. However, people spend most of their time indoors exposed to a combination of indoor-generated particles and ambient particles that have infiltrated. Thus, it is important to investigate the differential health effects of indoor- and ambient-generated particles. We combined our recently adapted recursive model and a predictive model for estimating infiltration efficiency to separate personal exposure (E) to PM(2.5) (PM with aerodynamic diameter ≤2.5 μm) into its indoor-generated (E(ig)) and ambient-generated (E(ag)) components for 19 children with asthma. We then compared E(ig) and E(ag) to changes in exhaled nitric oxide (eNO), a marker of airway inflammation. Based on the recursive model with a sample size of eight children, E(ag) was marginally associated with increases in eNO [5.6 ppb per 10-μg/m(3) increase in PM(2.5); 95% confidence interval (CI), −0.6 to 11.9; p = 0.08]. E(ig) was not associated with eNO (−0.19 ppb change per 10μg/m(3)). Our predictive model allowed us to estimate E(ag) and E(ig) for all 19 children. For those combined estimates, only E(ag) was significantly associated with an increase in eNO (E(ag): 5.0 ppb per 10-μg/m(3) increase in PM(2.5;) 95% CI, 0.3 to 9.7; p = 0.04; E(ig): 3.3 ppb per 10-μg/m(3) increase in PM(2.5); 95% CI, −1.1 to 7.7; p = 0.15). Effects were seen only in children who were not using corticosteroid therapy. We conclude that the ambient-generated component of PM(2.5) exposure is consistently associated with increases in eNO and the indoor-generated component is less strongly associated with eNO

Workgroup Report: Workshop on Source Apportionment of Particulate Matter Health Effects—Intercomparison of Results and Implications

Although the association between exposure to ambient fine particulate matter with aerodynamic diameter < 2.5 μm (PM(2.5)) and human mortality is well established, the most responsible particle types/sources are not yet certain. In May 2003, the U.S. Environmental Protection Agency’s Particulate Matter Centers Program sponsored the Workshop on the Source Apportionment of PM Health Effects. The goal was to evaluate the consistency of the various source apportionment methods in assessing source contributions to daily PM(2.5) mass–mortality associations. Seven research institutions, using varying methods, participated in the estimation of source apportionments of PM(2.5) mass samples collected in Washington, DC, and Phoenix, Arizona, USA. Apportionments were evaluated for their respective associations with mortality using Poisson regressions, allowing a comparative assessment of the extent to which variations in the apportionments contributed to variability in the source-specific mortality results. The various research groups generally identified the same major source types, each with similar elemental makeups. Intergroup correlation analyses indicated that soil-, sulfate-, residual oil-, and salt-associated mass were most unambiguously identified by various methods, whereas vegetative burning and traffic were less consistent. Aggregate source-specific mortality relative risk (RR) estimate confidence intervals overlapped each other, but the sulfate-related PM(2.5) component was most consistently significant across analyses in these cities. Analyses indicated that source types were a significant predictor of RR, whereas apportionment group differences were not. Variations in the source apportionments added only some 15% to the mortality regression uncertainties. These results provide supportive evidence that existing PM(2.5) source apportionment methods can be used to derive reliable insights into the source components that contribute to PM(2.5) health effects

Working mechanisms of the use and acceptability of ecological momentary interventions:A realist evaluation of a guided self-help ecological momentary intervention targeting self-esteem

BackgroundTechnology improves accessibility of psychological interventions for youth. An ecological momentary intervention (EMI) is a digital intervention geared toward intervening in daily life to enhance the generalizability and ecological validity, and to be able to intervene in moments most needed. Identifying working mechanisms of the use of ecological momentary interventions might generate insights to improve interventions.MethodsThe present study investigates the working mechanisms of the use and acceptability of an ecological momentary intervention, named SELFIE, targeting self-esteem in youth exposed to childhood trauma, and evaluates under what circumstances these mechanisms of use and acceptability do or do not come into play. A realist evaluation approach was used for developing initial program theories (data: expert interviews and a stakeholders focus group), and subsequently testing (data: 15 interviews with participants, a focus group with therapists, debriefing questionnaire), and refining them.ResultsThe SELFIE intervention is offered through a smartphone application enabling constant availability of the intervention and thereby increasing accessibility and feasibility. When the intervention was offered on their personal smartphone, this enhanced a sense of privacy and less hesitance in engaging with the app, leading to increased disclosure and active participation. Further, the smartphone application facilitates the practice of skills in daily life, supporting the repeated practice of exercises in different situations leading to the generalizability of the effect. Buffering against technical malfunction seemed important to decrease its possible negative effects.ConclusionsThis study enhanced our understanding of possible working mechanisms in EMIs, such as the constant availability supporting increased accessibility and feasibility, for which the use of the personal smartphone was experienced as a facilitating context. Hereby, the current study contributes to relatively limited research in this field. For the field to move forward, mechanisms of use, and acceptability of EMIs need to be understood. It is strongly recommended that alongside efficacy trials of an EMI on specific target mechanisms, a process evaluation is conducted investigating the working mechanisms of use.Trial registrationThe current paper reports on a realist evaluation within the SELFIE trial (Netherlands Trial Register NL7129 (NTR7475))

Associations Between Asthma Emergency Visits and Particulate Matter Sources, Including Diesel Emissions from Stationary Generators in Tacoma, Washington

The objective of this research was to evaluate the effect of particulate matter air pollution, including emissions from diesel generators, on visits to emergency departments for asthma. Daily asthma case data from participating hospitals in the greater Tacoma, Washington area were obtained. Daily asthma emergency room visit data were available from six Tacoma hospitals from January 3, 1998 to May 30, 2002. Only emergency visits where the primary discharge diagnosis was asthma were included in the analysis. Air pollution, daily temperature and relative humidity data were obtained from the Puget Sound Clean Air Agency. An association between daily PM2.5 and emergency department (ED) visits for asthma at lag days 2 and 3 was observed. The relative risk for lag day 2 was 1.04 (95% confidence interval[CI]: 1.01, 1.07) and for lag day 3 was 1.03 (1.0, 1.06). A significant association between ED visits for asthma and increased use of diesel generators was not detected. The use of low-sulfur diesel oil may have mitigated potential adverse health effects. These data indicate that air pollution in a medium-sized coastal city may be sufficient to have a public health impact on asthma