Most time-series studies of particulate air pollution and acute health outcomes assess exposure of the study population using fixed-site outdoor measurements. To address the issue of exposure misclassification, we evaluate the relationship between ambient particle concentrations and personal exposures of a population expected to be at risk of particle health effects. IMPLICATIONSAs epidemiological studies aim to attribute observed health effects to outdoor air pollution, the contribution of outdoor air pollutants to population exposure must be assessed. To support time-series epidemiological studies that evaluate the health impacts of short-term changes in air pollution, an exposure metric is required for which the day-to-day variability in personal exposures reflects the variability of ambient concentrations being measured. We found that personal exposures to particulate sulfate in a group of subjects at risk for adverse health effects of particulate air pollution were highly correlated, over time, with ambient particle concentrations. Personal exposures to sulfate were highly correlated with ambient levels across all individuals and all levels of exposure, whereas correlations between personal exposures to PM 2.5 and ambient particle concentrations were lower and more variable. Overall, we have shown that a personal measure of exposure to outdoor source PM is highly related to variation in ambient levels of PM, lending support to time-series epidemiological studies.Sampling was conducted within the Vancouver metropolitan area during April-September 1998. Sixteen subjects (non-smoking, ages 54-86) with physician-diagnosed chronic obstructive pulmonary disease (COPD) wore personal PM 2.5 monitors for seven 24-hr periods, randomly spaced approximately 1.5 weeks apart. Time-activity logs and dwelling characteristics data were also obtained for each subject. Daily 24-hr ambient PM 10 and PM 2.5 concentrations were measured at five fixed sites spaced throughout the study region. SO 4 2-, which is found almost exclusively in the fine particle fraction and which does not have major indoor sources, was measured in all PM 2.5 samples as an indicator of accumulation mode particulate matter of ambient origin.The mean personal and ambient PM 2.5 concentrations were 18 µg/m 3 and 11 µg/m 3 , respectively. In analyses relating personal and ambient measurements, ambient concentrations were expressed either as an average of the values obtained from five ambient monitoring sites for each day of personal sampling, or as the concentration obtained at the ambient site closest to each subject's home. metric, the median r between personal and average ambient concentrations was 0.96 (range = 0.66 to 1.0). Use of the closest ambient site did not improve the median correlation of the group for either PM 2.5 or SO 4 2-. All pooled analyses resulted in lower correlation coefficients than the median correlation coefficient of individual regressions. Personal SO 4 2-was more highly correlated with all ambient measures than PM 2.5 ....
To examine hypotheses regarding air pollution health effects, we conducted an exploratory study to evaluate relationships between personal and ambient concentrations of particles with measures of cardiopulmonary health in a sample of patients with chronic obstructive pulmonary disease ( COPD ) . Sixteen currently non -smoking COPD patients ( mean age = 74 ) residing in Vancouver were equipped with a particle ( PM 2.5 ) monitor for seven 24 -h periods. Subjects underwent ambulatory heart monitoring, had their lung function and blood pressure ( BP ) measured, and recorded symptoms and medication use. Ambient PM 2.5 , PM 10 , sulfate, and gaseous pollutant concentrations were monitored at five sites within the study area. Although no associations between air pollution and lung function were statistically significant, an estimated effect of 3% and 1% declines in daily FEV 1 change ( ÁFEV 1 ) for each 10 g / m 3 increase in ambient PM 10 and PM 2.5 , respectively, was observed. Increases of 1 g / m 3 in personal or ambient sulfate were associated with 1.0% and 0.3% declines in ÁFEV 1 , respectively. Weak associations were observed between particle concentrations and increased supraventricular ectopic heartbeats and with decreased systolic BP. No consistent associations were observed between any particle metric and diastolic BP, heart rate, or heart rate variability ( r -MSSD or SDNN ) , symptom severity, or bronchodilator use. Of the pollutants measured, ambient PM 10 was most consistently associated with health parameters; the use of personal exposures did not improve the strength of any associations or lead to increased effect estimates.
We have analysed data on exacerbation rates, Expanded Disability Status Scale (EDSS) scores, and lesion burdens using the results of two neutralizing antibody (NAB) assays (CPE and MxA) from the pivotal relapsing-remitting multiple sclerosis (MS) trial of interferon beta-1b (IFNB) with a longitudinal approach, where the influence of NABs in individual patients is assessed by comparing responses during NAB-positive and NAB-negative periods. There are apparent influences on exacerbation rate related to dose of IFNB, titer level, and duration of positivity. With the MxA assay, exacerbation rates after switching to NAB-positive status are estimated to be 28% higher [95% confidence interval (CI): (-15%, 92%)] and -2% higher [95% CI: (-21%, 21%)] on the low- and high-dose IFNB arms, respectively. When compared with all NAB-negative periods, exacerbation rates during NAB-positive periods are estimated to be 29% higher [95% CI: (0%, 67%)] and 18% higher [95% CI: (0%, 40%)] on the low- and high-dose IFNB arms, respectively. When NAB-positive patients again become NAB-negative, no evidence of increased exacerbation rates could then be demonstrated. More detailed exploratory analyses indicate that the effects are most evident in the approximately 20% of patients developing high titers. In these patients, the influence of NABs may be self-limited, as titers often diminish or NABs become undetectable with time.
Leukotriene D4 (2 c 10(-9) mole), injected into the left circumflex coronary artery of anesthetized sheep, produced profound coronary vasoconstriction and impaired regional ventricular wall motion. This cardiac effect was neither inhibited by prior treatment of the sheep with a cyclooxygenase inhibitor nor associated with thromboxane B2 release into the coronary sinus. Intravenous FPL 55712 completely abolished the coronary vasoconstriction of leukotriene D4, but a significant reduction of regional wall shortening persisted.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.